Adolescence Obesity Risk Increases with Increased Screen Time: A Systematic Review and Dose-Response Meta-Analysis

DOI: https://doi.org/10.21203/rs.3.rs-1267652/v1

Abstract

Background: Adolescence is a critical time period in human life. Adolescence is associated with reduced physical activity and increased sedentary behaviors. In the current systematic review and dose-response meta-analysis, we evaluated the association between screen time and obesity risk among adolescents.

Methods: A systematic search from PubMed, Embase and Scopus electronic databases through September 2021 was performed. Studies that evaluated the association between screen time and obesity among adolescents up to September 2021 were retrieved. A total of 64 qualified studies were included into meta-analysis.

Results: The results of the two-class meta-analysis showed that adolescents at the highest category of screen time were 1.4 times more likely to develop obesity (OR=1.393; CI=1.264, 1.536; P <0.001). The results of subgrouping identified that continent was the possible heterogeneity source. No evidence of non-linear association between increased screen time and obesity risk among adolescents was observed (P-nonlinearity= 0.278).

Conclusion: For the first time, the current systematic review and meta-analysis revealed a positive association between screen time and obesity among adolescents without any dose-response evidence.

Registration: The protocol of the current work has been registered in the PROSPERO system (Registration number: CRD42021233899).

1. Background

Adolescence is a critical time period regarding physical activity-related behaviors since regular physical activity decreases and sedentary behavior increases in this time period [1, 2]. Screen-related physical activities like television watching are very common among adolescents particularly in modern societies; it is reported that, adolescents spend about 3 hours per day for screen activities [3]. Screen time constitutes an important part of an adolescent’s life; adolescents are major TV users [4]. Fifty seven percent of adolescents reported watching TV every day with an average time of 1 hour and 49 minutes of TV watching [5]. Recent evidence has shown that increased screen-related sedentary behaviors had led not only to obesity growth [6], but also to mental problems among adolescents [7]. Sedentary behavior guidelines recommends less than two hours per day of recreational screen time for youth [8]. However, it has been estimated that more than 50% of adolescents exceed these recommendations for screen-related behaviors [9]. In a report from the Health Behavior in School-Age Children (HBSC), which was performed among adolescents aged 11, 13 and 15 years from 41 countries in Europe and in North America, 56–65% of the adolescents spent 2 h or more per day watching television [10]. Actually, sedentary behaviors are characterized by activities with low energy expenditure (< 1.5 metabolic equivalents) in a sitting position like television watching or other screen behaviors [11] and is an important risk factor for cardio-metabolic disease in adulthood [1215]. In adolescents, obesity is associated with dyslipidemia, glucose intolerance, and hypertension [16]. In a population based study of 5625 adolescents in Iran [17], high screen time was positively associated with high blood pressure, high low density lipoprotein cholesterol and triglyceride amount (P < 0.05). Numerous studies have reported the association between screen time and adiposity among adolescents; however, the results are inconsistent. Some of the studies reported increased odds of obesity by increasing screen time [16, 18, 19]; for example, in the study by Cheng L [18], among 2201 Chinese adolescents, increased odds of obesity for those with more than 2 hours/ day screen time (1.53; CI = 0.95–2.09; P < 0.001). While in another population-based school setting study by Lopez-Gonzalez D [20] among 1319293 adolescents of 12–14 years old, no significant association between obesity and screen time was reported. Several other studies also reported no association between obesity and screen time [2023]. Or, in some of the studies, only watching television or playing video games of more than three hours per day increased obesity risk among adolescents [2426]. More surprisingly, a non-significant reduced risk of excess weight by increased screen time of more than 4 hours/day was observed in De-Lima et al study [27] (0.87 CI = 0.59–1.30). According to the review of literature, a great between-study heterogeneity was observed in studies that evaluated the association between screen time and obesity among adolescents. It seems that the type of the screen (TV, PC, DVD or video games and etc.) or the duration of screen use and several other factors possibly affect the association of obesity with screen time. Therefore, in the current systematic review and meta-analysis, we systematically searched and analyzed all of the available literature that evaluated the association between obesity and screen time and we also classified the results according to numerous factors including screen type, time, geographical distribution, setting, obesity status as well as studies’ quality and sample size to identify possible determinants of these associations.

2. Methods

The results are reported according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta‐Analyses) checklist (Sup. Table 1) [28]. The protocol’s registration code in PROSPERO is CRD42021233899. 

a. Search Strategy, selection of studies, inclusion and exclusion criteria 

A total of 6291 articles were retrieved after searching from PubMed, Embase and Scopus electronic databases thorugh September 2021 (Figure 1). Search strategy for PubMed is provided in Sup. Table 2 and it has been adopted for each electronic database. Duplicate were removed and some of records were excluded according to title/ abstarct, as a consequent, 2156 full-text articles were remained for final screening by two independent investigators. Then, 2092 manuscripts were removed because of not meeting the inclusion criteria. Finally, 64 manuscripts with the total number of 1425738 participants were included in the final meta-synthesis. 

The following studies were included (1) observational designs (case control, cross-sectional or cohort studies with the baseline measurement of study parameters); (2) studies that evaluated the relationship (OR, RR or HR) between screen time and risk of obesity (3) the studies that were conducted only among adolescents (10 years ≤ age).   

b. Data extraction and quality assessment 

Data extraction was done in a standard EXCELL datasheet and was performed by two authors. The information that was included into data sheet were the name of first author and journal, publication year, country, setting,   age range and number of participants, study design, adjusted covariate, gender, obesity and screen time definition, weight, height and screen time measurement tools, and main results of the studies. Any disagreements between reviewers were resolved by discussion. The methodological quality of studies were assessed using the Agency for Healthcare Research and Quality (AHRQ) checklist [29]. (Table 1).

c. Statistical analysis 

The studies that reported the odds ratio of obesity (OR) in those with highest versus lowest screen time were included in two separate meta-analysis. Hozo et al [30] method was used when the median and rang were reported instead of mean and SD, and the median values were considered as best estimates of mean when sample size of study was more than 25 and the SD was calculated as follows:  Also, Walter and Yao method was used for missing SDs calculation, as SD = (b-a)/4 [31, 32]. If the number of participants in categories were not provided, equal number of participants in each category was assumed. When the odds ratio was not provided and the data of the exposure of variable in the groups were available, we calculated prevalence odds ratios (PORs) as suggested by Pearce N as the best approach for measuring effect size in prevalence studies [33] as follows:  While P0 and P1 are the prevalence in exposed and non-exposed groups. Cochran's Q and I-squared tests were used to identify between-study heterogeneity. The possible sources of heterogeneity were identified using subgrouping and meta-regression analysis. STATA version 13 (STATA Corp, College Station, TX, USA), was used for data analysis and P-values less than 0.05 were considered as statistically significant.

Only the studies that reported at least three categories for screen time and the odds or prevalence of obesity were included in the dose-response meta-analysis. Accordingly, thirteen individual studies in five articles were included [34-46]. The median point in each screen time category was identified and when medians were not reported, then approximate medians using the midpoint of the lower and upper limits were estimated. When the lowest or highest screen time categories were open-ended, the screen time was calculated by assuming the similar interval for those categories and estimating the mid-point. The reference category was the lowest one assuming OR and CIs of 1 for it. The potential non- linear associations were assessed using random‐effects dose‐response meta‐analysis by defining the restricted cubic splines with three knots at fixed percentiles (10%, 50% and 90%) of distribution and were used to calculate study‐specific odds ratios.

3. Results

a. Study characteristics 

General characteristics of included studies are represented in Table 2. In the meta-analysis of the odds of obesity among high screen-user adolescents compared with less-users, totally, 64 individual studies were included; the study by Lopez Gonzalez the association of obesity with screen time was reported for boys and girls separately, so the results were also included as two independent results [20]. Similarly, was the study by Franceschin MJ [16] that reported the results of TV and PC, VG separately. The study by Zulfiqar T [25], provided results for TV use in weekdays, electronic game playing in weekdays, TV use in weekends and electronic game playing in weekends among immigrant boys and girls from high income and lower than middle income countries separately; therefore, the results were included as six studies in the analysis. In the studies by Pabon et al [47] and Haidar A et al [21], the results were reported separately for overweight and obesity. The study by Saha M et al [23] reported the results for PC, TV and video games separately. The study by Hu EY [48] reported the results for TV and video, computer game and computer use separately, so, it was included as two separate studies. Similarly the study by Godakanda I [49] reported the results separately for TV watching and Video/DVD watching. So, the results were included as two independent results. The study by Watharkar A [50] reported the results for TV, PC or cell phone separately. The study by Velásquez-Rodríguez CM [51] was reported separate results for healthy adolescents and adolescents with insulin resistance. The study by De Jong E et al [52] was reported as four studies of TV watchers of 1-1.5 and more than 1.5 hours and PC users of less than 30 minutes/day and more than 30 minutes per day. The studies by Ercan S [53] and El-Gilany AH [54] reported the results for TV and PC use of more than 2 hours for overweight and obese adolescents. The study by Drake KM [55], reported the screen time of 0-7, 7-14 and more than 14 hours for overweight + obese or obese adolescents separately. The study by Byun W [56] reported the results for overweight and obese adolescents separately. The study by Adesina AF [57] reported the results of TV watching for 0-2 hours, 3-4 hours and ≥5 hours for overweight and obese; so the results we included as four independent studies. Sun Y [24] reported separate results for girls and boys. Finally, Collins AE [26] reported the separate results for PC use and play station. 

The results of the meta-analysis

The results of the two-class meta-analysis is presented in Figure 2. As it is shown, adolescents who were in the highest category of screen time were 1.2 times more likely to develop obesity compared with those in the lowest category [OR=1.393; CI=1.264, 1.536; P <0.001; I-squared (variation in ES attributable to heterogeneity) = 85.9%]. The results of subgrouping is shown in Table 3. Subgrouping according to continent reduced heterogeneity in some degree. For example, studies that were performed in America had the lowest heterogeneity. But other parameters were not potent sources of heterogeneity. The results of dose-response relationship between screen time and obesity among children is presented in Figure 3. There was no evidence of non-linear association between increased screen time and obesity risk among a (P-nonlinearity= 0.278).  Funnel plots indicating publication bias are presented in Figure 4. The results of Begg and Eggers test showed some evidence of publication bias (Egger’s P-value = 0.001; Begg’s P-value = 0.001). Therefore, trim and fill analysis was done (Figure 5) and the obtained result was as follows: OR=1.575; CI= 1.083, 2.068; P <0.001).

4. Discussion

In the current meta-analysis, for the first time, we summarized the results of studies that evaluated the association between screen time and obesity risk among adolescents. In an appropriate number of participants (e.g. 1425738) we revealed that high screen time is associated with 1.2 time higher chance of obesity among teenagers. No evidence of non-linear association was observed in the dose-response analysis. Previous population based studies have revealed the obesity-promoting effects of high screen time; in the study by Lopez-Gonzalez D [20], in screening of more than 7511 registered schools, high screen time was considered as an obesogenic factor. Several other studies also revealed that screen time more than 2 or 3 hours per day increases the risk of obesity [18, 25]. Internet addicted adolescents had also elevated risk of obesity in one study [19]. However, several other studies reported no significant association between obesity and screen time was observed [22, 27, 47]. The possible strong reason for this inconsistency, is the type of screen (e.g. TV, video games or personal computer and so on) that is used in numerous studies. For finding the answer, we performed subgroup analysis; according to the results, those studies that defined video games as their screen failed to reveal a positive association between screen time and obesity [23, 47, 58]. In the study by Franceschin MJ et al [16] adolescents with watching TV more than two hours per day had almost doubled chance of being obese compared with those who had less than 2 hours per day TV watching (OR = 1.73; 95%CI = 1.24–2.42) while the association was not significant for video game playing or PC use. In the study by Sun Y et al [24], the positive association between video game playing and obesity risk was noly observed among girls and not boys. Zulfiqar T et al [25], also reported the positive association between obesity and TV viewing and not for video games. Therefore, it seems that TV watching is a stronger motivator of obesity among adolescents. It is possibly because that some of video games can increase physical activity and physical health; in a meta-analysis by Primack BA et al [59], video games were associated with 69% improve in psychological therapy outcomes and 50% improve in physical activity outcomes. In another study by Williams WA [60], active video games were introduced as effective tools to improve physical activity among adolescents and were considered as a more acceptable and sustainable approach than many conventional methods.

High screen time, as a sedentary behavior, reduces lipoprotein lipase activity (LPL), and leads to reduced plasma triglycerides’ absorption by skeletal muscles, reduced HDL level and postprandial increase in serum lipids, that consequently results in fat deposition in vessels or adipose tissue [61, 62]. Moreover, increased screen time increases food intake; previous studies revealed that television watching increases motivated response to food intake and snacking behavior among children and adolescents [4, 6365]; this is also true for video games [6668] and personal computer use [69, 70]. More importantly, several TV food advertisements promote junk food and fast food consumption and increasing obesity risk [71–74]. Therefore, the association between obesity and screen use is a multi-dimensional factor that all of its aspects needs to be clearly studied. Also, the results of included studies in the current meta-analysis were reported in a combination of both genders, therefore, it was not possible to give gender-specific results.

5. Conclusion

As mentioned before, the current meta-analysis is the first study that provided a quantitative result for the association between different screens with obesity among adolescents. Since the results were not separable for boys and girls, therefore, further studies with separate results for males and females and different screen devices are needed to better explain the obtained results.

Declarations

Ethical approval and consent to participate

The protocol of the current work has been registered in the PROSPERO system (Registration number: CRD42021243523). Also, the research has been approved by the ethics committee of Tabriz University of Medical Sciences (Identifier: 63190).  

Consent to publish 

Not applicable. 

Availability of data and materials 

The data that support the findings of this study are available from Tabriz University of Medical Sciences but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of corresponding author.

Competing interest 

The authors declare that there is no conflict of interest. 

Funding 

None. 

Authors’ contributions

All authors have read and approved the manuscript; MAF, supervised the project, performed the search, extraction and wrote the first draft of the manuscript and analyzed the data. LJ was also involved in search, extraction and revision of the paper. She also was involved in data analysis. 

Acknowledgement

Not applicable. 

Authors’ information 

Department of Community Nutrition, School of Nutrition and Food Sciences, Tabriz University of Medical Sciences

2 Health Education and Health Promotion Department, School of Health, Tabriz University of Medical Sciences

References

  1. Suchert, V., Hanewinkel, R., Isensee, B. (2016) Screen time, weight status and the self-concept of physical attractiveness in adolescents. Journal of adolescence,48,11 – 7.
  2. Pate RR, Mitchell J, Byun W, Dowda M. (2011) Sedentary behaviour in youth. British journal of sports medicine,45(11,906e13.
  3. Hardy LL, Dobbins T, Booth ML, Denney-Wilson E, Okely AD. (2006) Sedentary behaviours among Australian adolescents.. Aust New Zealand J Public Health,30(), ,534e40.
  4. Domoff, S. E., Sutherland, E., Yokum, S., Gearhardt, A. N. (2021) The association of adolescents’ television viewing with Body Mass Index percentile, food addiction, and addictive phone use. Appetite,157.
  5. Rideout V, Robb M. (2019) The Common Sense Census: Media use by tweens and teens. Common Sense Media,1–104.
  6. Throuvala, M. A., Griffiths, M. D., Rennoldson, M., Kuss, D. J. (2020) The Role of Recreational Online Activities in School-Based Screen Time Sedentary Behaviour Interventions for Adolescents: A Systematic and Critical Literature Review. International Journal of Mental Health and Addiction.
  7. Twenge JM, Martin GN, Campbell WK. (2018) Decreases in psychological well-being among American adolescents after 2012 and links to screen time during the rise of smartphone technology.. Emotion,18,765–80.
  8. Tremblay, M. S., LeBlanc, A. G., Janssen, I., Kho, M. E., Hicks, A., Murumets, K., et al. (2011) Canadian sedentary behaviour guidelines for children and youth. Applied Physiology, Nutrition and Metabolism,36,59–64.
  9. Sisson, S. B., Church, T. S., Martin, C. K., Tudor-Locke, C., Smith, S. R., Bouchard, C., et al. (2009) Profiles of sedentary behavior in children and adolescents: The US National Health and Nutrition Examination Survey, 20012006. International Journal of Pediatric Obesity,4,353-9.
  10. Currie C, Zanotti C, Morgan A. (2012) Social determinants of health and well-being among young people Health Behaviour in School-aged Children (HBSC): international report from the 2009/2010 survey. Health policy for children and adolescents. WHO Regional Office for Europe,1–252.
  11. Coombs, N. A., Stamatakis, E. (2015) Associations between objectively assessed and questionnaire-based sedentary behaviour with BMI-defined obesity among general population children and adolescents living in England. BMJ open,5,e007172.
  12. Guillaume, M., Lapidus, L., Björntorp, P., Lambert, A. (1997) Physical activity, obesity, and cardiovascular risk factors in children. The Belgian Luxembourg Child Study II. Obesity research,5,549 – 56.
  13. Burke, V., Beilin, L. J., Simmer, K., Oddy, W. H., Blake, K. V., Doherty, D., et al. (2005) Predictors of body mass index and associations with cardiovascular risk factors in Australian children: A prospective cohort study. International journal of obesity,29,15–23.
  14. Martinez-Gomez, D., Rey-López, J. P., Chillón, P., Gómez-Martínez, S., Vicente-Rodríguez, G., Martín-Matillas, M., et al. (2010) Excessive TV viewing and cardiovascular disease risk factors in adolescents. The AVENA cross-sectional study. BMC public health,10,274.
  15. Mota, J., Ribeiro, J. C., Carvalho, J., Santos, M. P., Martins, J. (2010) Television viewing and changes in body mass index and cardiorespiratory fitness over a two-year period in schoolchildren. Pediatric exercise science,22,245 – 53.
  16. Franceschin, M. J., da Veiga, G. V. (2020) Association of cardiorespiratory fitness, physical activity level, and sedentary behaviour with overweight in adolescents. Revista Brasileira de Cineantropometria e Desempenho Humano,22,1–12.
  17. Safiri, S., Kelishadi, R., Qorbani, M., Abbasi-Ghah-Ramanloo, A., Motlagh, M. E., Ardalan, G., et al. (2015) Screen time and its relation to cardiometabolic risk among children and adolescents: The CASPIAN-III study. Iranian Journal of Public Health,44,35–44.
  18. Cheng, L., Li, Q., Hebestreit, A., Song, Y., Wang, D., Cheng, Y., et al. (2020) The associations of specific school-and individual-level characteristics with obesity among primary school children in Beijing, China. Public health nutrition,23,1838-45.
  19. Dalamaria, T., De Jesus Pinto, W., Dos Santos Farias, E., De Souza, O. F. (2021) Internet addiction among adolescents in a western brazilian amazonian city. Revista Paulista de Pediatria,39.
  20. Lopez-Gonzalez, D., Partida-Gaytán, A., Wells, J. C., Reyes-Delpech, P., Avila-Rosano, F., Ortiz-Obregon, M., et al. (2020) Obesogenic lifestyle and its influence on adiposity in children and adolescents, evidence from mexico. Nutrients,12.
  21. Haidar, A., Ranjit, N., Archer, N., Hoelscher, D. M. (2019) Parental and peer social support is associated with healthier physical activity behaviors in adolescents: A cross-sectional analysis of Texas School Physical Activity and Nutrition (TX SPAN) data. BMC public health,19.
  22. Kerkadi, A., Sadig, A. H., Bawadi, H., Thani, A. A. M. A., Chetachi, W. A., Akram, H., et al. (2019) The relationship between lifestyle factors and obesity indices among adolescents in Qatar. International journal of environmental research and public health,16.
  23. Saha, M., Adhikary, D. K., Parvin, I., Sharma, Y. R., Akhter, F., Majumder, M. (2018) Obesity and Its Risk Factors of among School Children in Sylhet, Bangladesh. Journal of Nepal Health Research Council,16,205–8.
  24. Sun, Y., Sekine, M., Kagamimori, S. (2009) Lifestyle and overweight among Japanese adolescents: The Toyama birth Cohort Study. Journal of epidemiology,19,303 – 10.
  25. Zulfiqar, T., Strazdins, L., Dinh, H., Banwell, C., D'Este, C. (2019) Drivers of Overweight/Obesity in 4–11 Year Old Children of Australians and Immigrants; Evidence from Growing Up in Australia. Journal of immigrant and minority health,21,737 – 50.
  26. Collins, A. E., Pakiz, B., Rock, C. L. (2008) Factors associated with obesity in Indonesian adolescents. International journal of pediatric obesity: IJPO : an official journal of the International Association for the Study of Obesity,3,58–64.
  27. De Lima, T. R., Moraes, M. S., Andrade, J. H. C., De Farias, J. M., Silva, D. A. S. (2020) Associated factors with the isolated and simultaneous presence of overweight and abdominal obesity in adolescents. Revista Paulista de Pediatria,38.
  28. Moher, D., Liberati, A., Tetzlaff, J., Altman, D. G. (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Annals of internal medicine,151,264-9.
  29. Cho CE, Taesuwan S, Malysheva OV, Bender E, Tulchinsky NF, Yan J. (2017) Trimethylamine-N-oxide (TMAO) response to animal source foods varies among healthy young men and is influenced by their gut microbiota composition: a randomized controlled trial.. Mol Nutr Food Res 61,1600324.
  30. Hozo, S. P., Djulbegovic, B., Hozo, I. (2005) Estimating the mean and variance from the median, range, and the size of a sample. BMC medical research methodology,5,13.
  31. Weir, C. J., Butcher, I., Assi, V., Lewis, S. C., Murray, G. D., Langhorne, P., et al. (2018) Dealing with missing standard deviation and mean values in meta-analysis of continuous outcomes: a systematic review. BMC medical research methodology,18,25.
  32. Walter, S., Yao, X. (2007) Effect sizes can be calculated for studies reporting ranges for outcome variables in systematic reviews. Journal of clinical epidemiology,60,849 – 52.
  33. N, P. (2004) Effect Measures in Prevalence Studies. Environ Health Perspect 112,1047–50.
  34. Li, L., Shen, T., Wen, L. M., Wu, M., He, P., Wang, Y., et al. (2015) Lifestyle factors associated with childhood obesity: A cross-sectional study in Shanghai, China. BMC research notes,8.
  35. Bhadoria, A. S., Kapil, U., Kaur, S. (2015) Association of duration of time spent on television, computer and video games with obesity amongst children in national capital territory of Delhi. International Journal of Preventive Medicine,2015-September.
  36. Bingham, D. D., Varela-Silva, M. I., Ferrão, M. M., Augusta, G., Mourão, M. I., Nogueira, H., et al. (2013) Socio-demographic and behavioral risk factors associated with the high prevalence of overweight and obesity in portuguese children. American Journal of Human Biology,25,733 – 42.
  37. Koleilat, M., Harrison, G. G., Whaley, S., McGregor, S., Jenks, E., Afifi, A. (2012) Preschool enrollment is associated with lower odds of childhood obesity among WIC participants in LA County. Maternal and child health journal,16,706 – 12.
  38. Taylor, A. W., Winefield, H., Kettler, L., Roberts, R., Gill, T. K. (2012) A population study of 5 to 15 year olds: full time maternal employment not associated with high BMI. The importance of screen-based activity, reading for pleasure and sleep duration in children's BMI. Maternal and child health journal,16,587 – 99.
  39. Balaban, G., Motta, M. E., Silva, G. A. (2010) Early weaning and other potential risk factors for overweight among preschool children. Clinics (Sao Paulo, Brazil),65,181-7.
  40. Fulton, J. E., Wang, X., Yore, M. M., Carlson, S. A., Galuska, D. A., Caspersen, C. J. (2009) Television viewing, computer use, and BMI among U.S. children and adolescents. Journal of physical activity & health,6 Suppl 1,S28-35.
  41. Khader, Y., Irshaidat, O., Khasawneh, M., Amarin, Z., Alomari, M., Batieha, A. (2009) Overweight and obesity among school children in Jordan: Prevalence and associated factors. Maternal and child health journal,13,424 – 31.
  42. Steele, R. M., Van Sluijs, E. M. F., Cassidy, A., Griffin, S. J., Ekelund, U. (2009) Targeting sedentary time or moderate- and vigorous-intensity activity: Independent relations with adiposity in a population-based sample of 10-y-old British children. American Journal of Clinical Nutrition,90,1185–92.
  43. Da Costa Ribeiro, I., Taddei, J. A. A. C., Colugnatti, F. (2003) Obesity among children attending elementary public schools in Sao Paulo, Brazil: A case-control study. Public health nutrition,6,659 – 63.
  44. Lagiou, A., Parava, M. (2008) Correlates of childhood obesity in Athens, Greece. Public health nutrition,11,940-5.
  45. Stettler, N., Signer, T. M., Suter, P. M. (2004) Electronic games and environmental factors associated with childhood obesity in Switzerland. Obesity research,12,896–903.
  46. Utter, J., Scragg, R., Schaaf, D. (2006) Associations between television viewing and consumption of commonly advertised foods among New Zealand children and young adolescents. Public health nutrition,9,606 – 12.
  47. Rincón-Pabón, D., Urazán-Hernández, Y., González-Santamaría, J. (2019) Association between the time spent watching television and the sociodemographic characteristics with the presence of overweight and obesity in Colombian adolescents (secondary analysis of the ENSIN 2010). PloS one,14,e0216455.
  48. Hu, E. Y., Ramachandran, S., Bhattacharya, K., Nunna, S. (2018) Obesity Among High School Students in the United States: Risk Factors and Their Population Attributable Fraction. Preventing chronic disease,15,E137.
  49. Godakanda, I., Abeysena, C., Lokubalasooriya, A. (2018) Sedentary behavior during leisure time, physical activity and dietary habits as risk factors of overweight among school children aged 14–15 years: case control study. BMC research notes,11,186.
  50. Watharkar, A., Nigam, S., Martolia, D. S., Varma, P., Barman, S. K., Sharma, R. P. (2015) Assessment of risk factors for overweight and obesity among school going children in Kanpur, Uttar Pradesh. Indian Journal of Community Health,27,216 – 22.
  51. Velásquez-Rodríguez, C. M., Velásquez-Villa, M., Gómez-Ocampo, L., Bermúdez-Cardona, J. (2014) Abdominal obesity and low physical activity are associated with insulin resistance in overweight adolescents: a cross-sectional study. BMC pediatrics,14,258.
  52. De Jong, E., Visscher, T. L. S., Hirasing, R. A., Heymans, M. W., Seidell, J. C., Renders, C. M. (2013) Association between TV viewing, computer use and overweight, determinants and competing activities of screen time in 4- to 13-year-old children. International journal of obesity,37,47–53.
  53. Ercan, S., Dallar, Y. B., Önen, S., Engiz, O. (2012) Prevalence of obesity and associated risk factors among adolescents in Ankara, Turkey. JCRPE Journal of Clinical Research in Pediatric Endocrinology,4,204–7.
  54. El-Gilany, A. H., El-Masry, R. (2011) Overweight and obesity among adolescent school students in mansoura, Egypt. Childhood Obesity,7,215 – 22.
  55. Drake, K. M., Beach, M. L., Longacre, M. R., MacKenzie, T., Titus, L. J., Rundle, A. G., et al. (2012) Influence of sports, physical education, and active commuting to school on adolescent weight status. Pediatrics,130,e296-e304.
  56. Byun, W., Dowda, M., Pate, R. R. (2012) Associations between screen-based sedentary behavior and cardiovascular disease risk factors in Korean youth. Journal of Korean medical science,27,388 – 94.
  57. Adesina, A. F., Peterside, O., Anochie, I., Akani, N. A. (2012) Weight status of adolescents in secondary schools in port Harcourt using Body Mass Index (BMI). Italian journal of pediatrics,38,31.
  58. Zhang, Y., Zhang, X., Li, J., Zhong, H., Pan, C. W. (2020) Associations of outdoor activity and screen time with adiposity: findings from rural Chinese adolescents with relatively low adiposity risks. BMC public health,20.
  59. Primack, B. A., Carroll, M. V., McNamara, M., Klem, M. L., King, B., Rich, M., et al. (2012) Role of video games in improving health-related outcomes: a systematic review. American journal of preventive medicine,42,630–8.
  60. Williams, W. M., Ayres, C. G. (2020) Can Active Video Games Improve Physical Activity in Adolescents? A Review of RCT. International journal of environmental research and public health,17,669.
  61. Pitanga, F. J. G., Alves, C. F. A., Pamponet, M. L., Medina, M. G., Aquino, R. (2016) Screen time as discriminator for overweight, obesity and abdominal obesity in adolescents. Revista Brasileira de Cineantropometria e Desempenho Humano,18,539 – 47.
  62. Edwardson CL, Gorely T, Davies MJ, Gray LJ, Khunti K, Wilmot EG. (2012) Association of sedentary behaviour with metabolic syndrome: a meta-analysis.. PloS one,7,e34916.
  63. Temple, J. L., Giacomelli, A. M., Kent, K. M., Roemmich, J. N., Epstein, L. H. (2007) Television watching increases motivated responding for food and energy intake in children. American Journal of Clinical Nutrition,85,355 – 61.
  64. Borghese, M., Tremblay, M., Leduc, G., Boyer, C., Belanger, P., LeBlanc, A., et al. (2014) Television viewing and food intake pattern of normal weight, overweight, and obese 9–11 year-old Canadian children. Obesity Reviews,15,232.
  65. Taveras, E. M., Sandora, T. J., Shih, M. C., Ross-Degnan, D., Goldmann, D. A., Gillman, M. W. (2006) The association of television and video viewing with fast food intake by preschool-age children. Obesity (Silver Spring, Md),14,2034-41.
  66. Chaput, J. P., Visby, T., Nyby, S., Klingenberg, L., Gregersen, N. T., Tremblay, A., et al. (2011) Video game playing increases food intake in adolescents: a randomized crossover study. The American journal of clinical nutrition,93,1196 – 203.
  67. Cessna, T., Raudenbush, B., Reed, A., Hunker, R. (2007) Effects of video game play on snacking behavior. Appetite,49,282.
  68. Chaput, J. P., Tremblay, A., Pereira, B., Boirie, Y., Duclos, M., Thivel, D. (2015) Food intake response to exercise and active video gaming in adolescents: effect of weight status. British Journal of Nutrition,115,547 – 53.
  69. Shi, L., Mao, Y. (2010) Excessive recreational computer use and food consumption behaviour among adolescents. Italian journal of pediatrics,36,1–4.
  70. Fulton, J. E., Wang, X., Yore, M. M., Carlson, S. A., Galuska, D. A., Caspersen, C. J. (2009) Television viewing, computer use, and BMI among US children and adolescents. Journal of physical activity and health,6,S28-S35.
  71. Gilbert-Diamond, D., Emond, J. A., Lansigan, R. K., Rapuano, K. M., Kelley, W. M., Heatherton, T. F., et al. (2017) Television food advertisement exposure and FTO rs9939609 genotype in relation to excess consumption in children. International journal of obesity (2005),41,23 – 9.
  72. Ustjanauskas, A. E., Harris, J. L., Schwartz, M. B. (2014) Food and beverage advertising on children's web sites. Pediatric obesity,9,362 – 72.

Tables

Table 1. Agency for Healthcare Research and Quality (AHRQ) checklist to assess quality of the cross-sectional studies 

ARHQ Methodology Checklist items for Cross-Sectional study

Zhang Y [58]

De-Lima TR [27]

Zulfiqar T [25]

 

Kerkadi A [22]

Hu J [75]

De-Jong E[52]

Franceschin MJ [16]

 

Dalamaria, T [19]

Cheng L [76]

1) Define the source of information (survey, record review)

2) List inclusion and exclusion criteria for exposed and unexposed subjects (cases and controls) or refer to previous publications

 

3) Indicate time period used for identifying patients

_

4) Indicate whether or not subjects were consecutive if not population-based

-

-

 

-

-

-

-

-

5) Indicate if evaluators of subjective components of study were masked to other aspects of the status of the participants

-

-

-

 

 

U

-

-

-

-

-

6) Describe any assessments undertaken for quality assurance purposes (e.g., test/retest of primary outcome measurements)

-

-

 

U

7) Explain any patient exclusions from analysis

_

-

-

8) Describe how confounding was assessed and/or controlled.

 

-

9) If applicable, explain how missing data were handled in the analysis

-

 

-

10) Summarize patient response rates and completeness of data collection

-

11) Clarify what follow-up, if any, was expected and the percentage of patients for which incomplete data or follow-up was obtained

-

-

-

-

-

-

-

-

Total score 

8

6

7

7

7

4

6

6

8


Table 1. Cont’d  

ARHQ Methodology Checklist items for Cross-Sectional study

Lopez-GonzalezD [20]

 

Pabón D [47]

Haidar A [21]

Saha M [23]

Mansoori M [77]

Godakanda I [49]

Talat MA[78]

Piryani MA [78]

Moradi G [79]

1) Define the source of information (survey, record review)

2) List inclusion and exclusion criteria for exposed and unexposed subjects (cases and controls) or refer to previous publications

 

 

 

 

 

 

3) Indicate time period used for identifying patients

4) Indicate whether or not subjects were consecutive if not population-based

 

 

-

 

-

-

-

 

-

 

 

-

-

5) Indicate if evaluators of subjective components of study were masked to other aspects of the status of the participants

 

 

U

 

 

U

 

 

U

-

-

 

 

U

 

 

U

 

 

U

-

6) Describe any assessments undertaken for quality assurance purposes (e.g., test/retest of primary outcome measurements)

 

U

 

U

 

U

-

 

U

 

U

 

U

-

7) Explain any patient exclusions from analysis

_

_

_

-

_

_

-

8) Describe how confounding was assessed and/or controlled.

 

 

 

-

 

 

 

9) If applicable, explain how missing data were handled in the analysis

 

 

 

-

-

 

 

-

 

-

-

10) Summarize patient response rates and completeness of data collection

-

-

-

-

-

-

-

11) Clarify what follow-up, if any, was expected and the percentage of patients for which incomplete data or follow-up was obtained

-

-

-

-

-

-

-

Total score 

8

5

4

4

7

7

5

4

4

 

 Table 1. Cont’d  

ARHQ Methodology Checklist items for Cross-Sectional study

Watharkar A [50]

 

De- Lucena  JMS [80]

 

Velásquez-RodríguezCM [51]

 

De Jong E [52]

Ercan S [53]

Collins AE [26]

Drake KM [55]

Sun Y [24]

Adesina AF [57]

El-Gilany AH [54]

Byun W [56]

1) Define the source of information (survey, record review)

 

2) List inclusion and exclusion criteria for exposed and unexposed subjects (cases and controls) or refer to previous publications

 

3) Indicate time period used for identifying patients

 

4) Indicate whether or not subjects were consecutive if not population-based

-

-

-

-

-

-

 

5) Indicate if evaluators of subjective components of study were masked to other aspects of the status of the participants

-

-

-

-

-

-

-

-

-

-

 

6) Describe any assessments undertaken for quality assurance purposes (e.g., test/retest of primary outcome measurements)

-

-

-

-

-

-

 

 

7) Explain any patient exclusions from analysis

-

-

-

 

8) Describe how confounding was assessed and/or controlled.

-

 

9) If applicable, explain how missing data were handled in the analysis

-

-

-

 

10) Summarize patient response rates and completeness of data collection

  •  

 

11) Clarify what follow-up, if any, was expected and the percentage of patients for which incomplete data or follow-up was obtained

-

-

-

-

-

-

-

-

 

Total score 

3

7

5

7

3

3

8

6

4

8

 



Table 2. The characteristics of studies that were included in the two-class meta-analysis of odds of obesity and increased screen time among adolescents  

Journal/ Year/ First author 

Country

Setting/ num 

Design 

Age (y)/ gender

Overweight/ obesity status and definition 

Disease status 

ST definition 

ST measurement 

Main findings  

Revista Paulista de Pediatria/ 2021/  Dalamaria T [19]

 

Brazil 

School/ 1387 

Cross-sectional 

14-18/ both 

Obesity/ ≥85th percentile of age

Healthy 

Internet addiction 

Questionnaire 

Increased odds of obesity in internet addicted adolescents [OR= 1.1; CI = 0.9-3.18].

BMC Public Health/ 2020/ Zhang  Y[58] 

China 

School/ 2264

Cross-sectional 

12- 15/ both 

Obesity/ ≥85th percentile of age

Healthy 

TV, VG, PC

Questionnaire 

Non-significant association between screen time and odds of obesity. 

Nutrients/ 2020/ Lopez-Gonzalez D [20]

Mexico 

School/ 

1319293

Cross-sectional 

12-17/ both 

Overweight/ obesity defined as ≤95th and ≥85th and ≥95th percentile of age respectively  

Healthy 

TV, electronic games 

Questionnaire 

Non-significant association between obesity and screen time. 

Rev Bras  Cineantropometri Desempenho Hum/ 2020/ Franceschin MJ [16]

 

Brazil 

School/ 1015

Cross-sectional 

15.3/ both 

Overweight/ obesity defined as 1 ≤BMI Z-score <2

Healthy 

TV, Video game or PC

Questionnaire 

A significant increased odds of overweight/ obesity in those with more than 2 hours per day TV watching (1.73 (1.24-2.42). The OR for PC and video games was 1.01 (0.71-1.45). 

Revista Paulista de Pediatria/ 2020/ De Lima TR [27]

Brazil 

School/ 583

Cross-sectional 

11-17/ both 

Overweight defined as  BMI Z-score≥ 1

Healthy 

TV, Video game or PC

Questionnaire

Non-significant reduced risk of excess weight by increased screen time of more than 4 hours/day (0.87 CI = 0.59-1.30) 

Public Health Nutrition/ 2020/ Cheng L [18]

 

China 

School/ 2201

Cross-sectional 

10/ both 

Obesity/ ≥95th percentile of age

Healthy 

TV/video games/ PC/iPad/ phone

Questionnaire 

Increased odds of obesity for those with more than 2 hours/ d screen time (1.53; CI= 0.95- 2.09) 

J Immigrant Minor  health/ 2019/  Zulfiqar T [25]

 

Australia 

Community/ 2215 +2000

Cross-sectional 

10-11/ both 

Overweight/ obesity +

BMI ≥ 25 kg/m2

Healthy 

TV, electronic games 

Questionnaire 

TV watching of more than 3 hours/ day in weekends was associated with odds of obesity in boys (1.4 (1.0,1.9) and girls (1.5 (1.1,1.9) P <0.05

In J Environ Res Pub Health/ 2019/ Kerkadi A [22]

Qatar 

Community/ 1161

Cross-sectional 

14-18/ both 

Overweight  25≤ BMI ≤ 30 kg/mand obesity BMI≥ 30  kg/m2

Healthy 

TV, Video game or PC

Questionnaire 

No significant association between screen time of more than 2 hours/ day and risk of overweight/ obesity (OR=1; CI= 0.7–1.4) 

 

Journal/ Year/ First author 

Country

Setting/ num 

Design 

Age (y)/ gender

Overweight/ obesity status and definition 

Disease status 

ST definition 

ST measurement 

Main findings  

Plos One/ 2019/ Pabon et al [47]

USA

Community/ 2358+546

Cross-sectional 

13-17/ both 

Overweight/ obesity defined as 1 ≤BMI Z-score <2

Healthy 

TV, Video game

Questionnaire 

No significant association between increased screen time and risk of overweight or obesity. 

BMC Public Health/ 2019/ Haidar A [21]

USA

School/ 6716

Cross-sectional 

14.88/ both 

Overweight/ obesity defined as ≤95th and ≥85th and ≥95th percentile of age respectively  

Healthy 

TV, DVD, movies 

Questionnaire 

No significant association between increased screen time and risk of overweight or obesity. 

J Nepal Health Res Counc/ 2018/ Saha M [23]

Bangladesh 

School/ 288

Cross-sectional 

10-14/ both 

Obesity defined as ≥95th percentile of age

Healthy 

TV, Video game, PC

Questionnaire 

No significant association between increased screen time and risk of overweight or obesity. 

Tropical Doctor/ 2018/ Mansouri N [77]

Pakistan 

School/ 887

Cross-sectional 

11-15/ both

Overweight defined as ≤95th and ≥85th percentile of age 

Healthy 

TV

Questionnaire 

Watching TV more than 2 hours/ day was associated with increased risk of overweight (6.42 (4.32–9.54) P <0.0001) 

Prev Chronic Dis/ 2018/ Hu EY[48]

USA

School/ 15624

Cross-sectional 

14- 18/ both

Obesity defined as ≥ 95th percentile of age

Healthy 

TV, Video or computer game, PC use

Questionnaire

Increased risk of obesity for those with more than 3 hours/ day TV watching ( 1.38 (1.09–1.76) and more than 3 hours video game or PC use (1.19 (0.98–1.43)

BMC Res Notes/  2018/ Godakanda I [49]

 

USA

School/ 880

Cross-sectional 

14-15/ both

Overweight defined as  BMI Z-score≥ 1

Healthy 

TV, Video/ DVD

Questionnaire

Television watching time ≥ 2 h/day (2.6 (1.7–3.8) and Video/DVD watching ≥ 2 h/day (3.1 (1.8-5.3) were associated with increased risk of overweight. 

Egypt Ped Assoc Gazette/ 2016/ Talat MA  [78]

 

 

Egypt 

School/ 32400 

Cross-sectional 

12-15/both

Overweight/ obesity defined as ≤95th and ≥85th and ≥95th percentile of age respectively  

Healthy 

TV

Questionnaire 

More than 2 hours TV watching was associated with increased risk of obesity (1.36 CI= 0.45–6.8; P = 0.048) 

BMJ Open/ 2016/ Piryani S [81]

 

Nepal 

School/ 360 

Cross-sectional 

16-19/ both 

Overweight defined as  BMI Z-score≥ 1

Healthy 

TV

Questionnaire 

 

Watching TV more than 2 hours/ day was associated with increased risk of obesity (OR= 8.86 (3.90 to 20.11) <0.001

Med J Islamic Rep Iran/ 2016/ Moradi G [79]

Iran 

School/ 2506

Cross-sectional 

10-12/ both 

Overweight/ obesity defined as ≤95th and ≥85th and ≥95th percentile of age respectively  

Healthy 

TV, VG

Questionnaire 

 

Screen time was associated with increased risk of overweight and obesity (1.41(1.17-1.69)

Indian J Comm Health/ 2015/ Watharkar A [50]

India 

School/ 806

Cross-sectional 

12-15/ both

Overweight/ obesity defined as ≤95th and ≥85th and ≥95th percentile of age respectively  

Healthy 

TV, PC, cell phone 

Questionnaire 

 

Increased risk of overweight obesity for those with more than 2 hours TV watching (OR=3.72; CI= 2.38-5.83) or more than 2 hours computer or mobile phone use (OR=1.68; CI= 1.09-2.57)

Revista Paulista de Pediatria/ 2015/  De Lucena JMS [80]

Brazil 

School/ 2874

Cross-sectional 

14-19/ both 

Overweight  25≤ BMI ≤ 30 kg/mand obesity BMI≥ 30  kg/m2

Healthy 

TV, PC, VG

Questionnaire 

Excessive screen time was associated with increased risk of overweight/ obesity (1.25 (0.93-1.67)

BMC Pediatr/ 2014/ Velásquez-Rodríguez CM [51] 

Finland 

Community/ 120 

Cross-sectional 

10-18/ both 

Overweight defined as ≤95th and ≥85th percentile of age 

Healthy and with insulin resistance 

TV

Questionnaire 

Increased risk of overweight in excessive TV watchers among adolescents with insulin resistance (OR= 2.39; CI= 0.94-6.05) but not among healthy adolescents. 

Int J Obes/ 2013/  De Jong E [52]

 

Netherland 

School/ 2429+2004+2068

Cross-sectional 

10-13/ both 

Overweight  25≤ BMI ≤ 30 kg/mand obesity BMI≥ 30  kg/m2

Healthy 

TV, PC 

Questionnaire 

No significant association between TV watching more than 1.5 hours or PC use of more than 30 minutes and overweight/ obesity.  

JCRPE/ 2012/  Ercan S [53]

Turkey 

School/ 8848

Cross- sectional 

11-18/ both 

Overweight  25≤ BMI ≤ 30 kg/mand obesity BMI≥ 30  kg/m2

Healthy 

TV, PC 

Questionnaire 

Increased risk of overweight and obesity for those with more than 2 hours TV watching or PC use. 

Pediatrics/ 2012/ Drake KM [55]

England 

School/ 1718

Cross-sectional 

12-18/ both 

Overweight/ obesity defined as ≤95th and ≥85th and ≥95th percentile of age respectively  

Healthy 

TV, DVD, video game 

Questionnaire 

Screen time of 7.1 -14 and >14 hours/week was associated with increased obesity risk of OR= 1.28 CI= 1.06, 1.55; P<0.05 and OR= 1.37 CI= 1.09, 1.71; P < 0.01 respectively. 

J Korean Med Sci/ 2012/ Byun W [56]

 

Korea 

Community/ 1033

Cross-sectional 

12-18/ both 

Overweight/ obesity defined as ≥ 95th percentile of age

Healthy 

TV, PC, video game 

Questionnaire

Increased risk of overweight and obesity was observed by increased screen time 

Ital J Pediatr / 2012/  Adesina AF[57]

Nigeria 

School/ 690 

Cross-sectional 

10-19/ both

Overweight  25≤ BMI ≤ 30 kg/mand obesity BMI≥ 30  kg/m2

Healthy 

TV 

Questionnaire

Increased risk of overweight and obesity was observed by increased screen time 

Childhood Obesity/ 2011/  El-Gilany AH [54]

 

Egypt 

School/ 953

Cross-sectional 

14-19/ both

Overweight defined as ≤95th and ≥85th percentile of age 

Healthy

TV, PC 

Questionnaire

Increased risk of overweight/ obesity for those with more than 2 hours TV watching (2.6 (1.7–3.9) or more than 2 hours computer use (1.8 (1.3–2.5)

J Epidemiol/ 2009/ Sun Y [24]

Japan

School/ 5753

Cross-sectional 

12-13/ both

Overweight  25≤ BMI ≤ 30 kg/m

Healthy

TV, VG  

Questionnaire

Watching TV more than 3 hours/ d was associated with increased risk of overweight in boys (OR=1.79; CI=1.21–2.67 and girls OR= 2.37; CI= 1.55–3.62; P <0.001

Int J Pediatr Obes/ 2008/  Collins AE[26]

Indonesia 

School/ 1758

Cross-sectional 

12-15/ both

Obesity defined as  BMI ≥ 25 kg/m

Healthy

PC, PS  

Questionnaire

Increased risk of obesity in those with more than 3 hours/ d PC use (OR= 1.85; CI= 1.04-3.29) or play station use (OR=1.94; CI= 1.23- 3.05)

Table 2. Cont’d. 

 

Table 3. Subgroup analysis for the odds of obesity in highest versus lowest screen-user adolescents  

I2, %

P heterogeneity

P between group *

P within group

OR (95% CI)

No. of studies*

Group

85.9

0.105

 

<0.001

1.393     1.264     1.536       

64

Total 

 

 

<0.001

 

 

 

Continent       

30

0.144

 

0.013

1.127     1.025     1.238

13

America 

92.6

<0.001

 

0.001

1.420     1.150     1.753

17

Europe 

87.2

<0.001

 

<0.001

1.834     1.477     2.276

19

Asia 

49.1

0.056

 

0.278

1.099     0.927     1.304

8

Oceania 

50.5

0.060

 

0.007

1.649     1.148     2.368

7

Africa 

 

 

<0.001

 

 

 

Screen type 

82.9

<0.001

 

<0.001

1.767        1.423     2.195

28

TV 

86.7

<0.001

 

0.007

1.628        1.141     2.325

10

PC

41.7

0.162

 

0.142

1.266        0.924     1.734

4

VG

71.1

<0.001

 

0.031

1.090     1.008     1.180

13

TV+VG

0.0

0.462

 

0.105

1.148     0.971     1.357

2

VG + PC

8.6

0.363

 

0.256

1.093     0.938     1.274

7

TV + VG + PC

 

 

<0.001

 

 

 

Age group 

79.1

<0.001

 

<0.001

1.498     1.253     1.790

28

<15

81.5

<0.001

 

0.001

1.587     1.203     2.094

8

≥15

88.5

<0.001

 

0.001

1.254     1.102     1.427

28

Both 

 

 

<0.001

 

 

 

Setting 

88.1

<0.001

 

    <0.001

1.518     1.332     1.730

51

School 

31.2

0.134

 

0.003

1.121     1.039     1.210

13

Community 

 

 

<0.001

 

 

 

Obesity status 

74.7

<0.001

 

<0.001

1.390     1.187     1.627

24

Obesity 

92.6

<0.001

 

0.001

1.551     1.203     2.001

13

Overweight 

85.3

<0.001

 

<0.001

1.331     1.157     1.530

27

Overweight/ obesity 

 

 

<0.001

 

 

 

Sample size

85.3

<0.001

 

<0.001

1.875     1.368     2.570

19

1000 >

61.7

<0.001

 

0.002

1.151        1.073     1.235

31

1000-5000

89.9

<0.001

 

<0.001

1.596        1.188     2.146

14

≥ 5000

 

 

<0.001

 

 

 

Study quality *

88.4

<0.001

 

<0.001

2.296     1.580     3.338

9

Low 

73.7

<0.001

 

<0.001

1.278     1.151     1.418

42

Moderate

84.4

<0.001

 

0.002

1.259     1.085     1.461

13

High  

*low quality = 0–3; moderate quality = 4–7; high quality ≥ 8; all of the included studies were in moderate quality group therefore, subgrouping was not performed.