Literature Searches
Seventy three systematic reviews were assessed, resulting in a list of 699 RCTs and NRSs. After duplicates were removed (n=284), a total of 415 citations remained for screening. After the update search, a total of 2209 citations were screened. One hundred and fifty three articles retrieved in full text, and 39 of them fulfilled the inclusion criteria (see Figure 1).
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Figure 1. Flow Chart
Description and Characteristics of Included studies
Nineteen included studies were RCT, while 20 included studies used NRS design, such as quasi-experimental controlled study design and pretest/ posttest controlled study design. Eighteen studies were carried out in the United States, seventeen studies in Europe and four studies in Australia. The studies included working populations from the following sectors: health care provider or insurance, services and administration, manufacturing, communication, education and multiple sectors. Sample sizes ranged from 25 to 155,543 employees (249,175 in total; mean sample size: 6,557; median sample size: 407.5). Seven studies were conducted in the 1990s, nine studies were conducted during the following decade, while twenty three of the included studies were published after 2010. The follow-up period ranged from 3 months to 8 years, with upwards of 12 months as the most common duration for 22 studies. The studies reported on physical activity (n=22), nutrition (n=1) or both physical activity and nutrition (n=16) interventions. The studies addressed either environmental-level (n=4) or multi-level interventions (n=35). The multi-level interventions were organizational- and individual-level interventions (n=14), environmental- and individual-level interventions (n=10) or environmental-, organizational- and individual-level interventions (n=11). The included intervention studies targeted work-related outcomes such as absenteeism, presenteeism, work performance, workability and productivity and diverse types of health-related outcomes, such as sedentary behavior, physical activity, musculoskeletal comfort, weight loss and health risks. Two environmental-level (29, 30) and three multilevel intervention studies (31-33) aimed either at physical activity or nutrition measured work performance using subjective and objective measurements. An environmental-level (34) and two multilevel intervention studies (35, 36) aimed at physical activity measured workability using Work Ability Index (WAI). Six multilevel intervention studies (37-42) aimed either at physical activity or physical activity and nutrition measured productivity using objective and subjective measurements, such as HPQ (Health & Work Performance Questionnaire), WPAIQ (Work Productivity and Activity Impairment Questionnaire), Work Limitations Questionnaire (WLQ). Fourteen multilevel intervention studies aimed either at physical activity or physical activity and nutrition measured absenteeism. Nine of them used objective measurements (company records) (43-51), while five studies used subjective measurements (52-56). An environmental-level (57) and ten multilevel intervention studies (58-67) aimed either at physical activity or physical activity and nutrition measured multiple work-related outcomes using objective and subjective measurements.
Table 1 presents the characteristics of the included studies (N=39) and the interventions they studied, while an overall description of the interventions and details of the study designs are presented in Additional file 2. The studies were stratified according to the level of intervention and the type of the intervention. Eight categories were compiled: environmental-level interventions aimed at physical activity (n=4); organizational- and individual-level interventions aimed at physical activity (n=7), at nutrition (n=1) and at both physical activity and nutrition (n=6); environmental- and individual-level interventions aimed at physical activity (n=7) and at both physical activity and nutrition (n=3); environmental-, organizational- and individual-level interventions aimed at physical activity (n=4) and at both physical activity and nutrition (n=7).
Quality Assessment
The overview of risk of bias assessment of the 19 RCTs is summarized in Additional file 3. The majority of the studies were assessed with a low or unclear risk of bias (see Cochrane Collaboration’s recommendations). Studies conducted before 2011 were assessed with an unclear risk of bias (31, 32, 36, 41, 55, 56), while more recent studies were assessed either with low (35, 37, 39, 57, 61, 63, 64) or unclear (30, 42, 58, 62) or high risk of bias (51, 66).
The overview of risk of bias assessment of the 20 NRSs is summarized in Additional file 3. None of the studies discussed deviations from intended interventions. According to Cochrane Collaboration’s recommendations, if there is a lack of information in one or more key domains of bias it is difficult to extract safe conclusion on which to base a judgment about risk of bias, as a result of which these studies are classified as no information. Thus, the studies were judged taking into consideration all the pre-intervention and at-intervention domains except bias due to deviations from intended interventions. The intervention studies were judged as having moderate risk of bias, as the majority of them provide sound evidence for a NRS but cannot be considered comparable to a well-performed randomized trial. Older studies (before 2011) were rated as having either moderate risk of bias (33, 43, 46, 47, 50, 52, 60) or no information (44, 48), while more recent studies were rated as having either low (29, 53, 54, 59) or moderate risk of bias (34, 38, 40, 45) or no information (65, 67).
Efficacy of workplace nutrition and/or physical activity interventions for work-related outcomes
Fourteen studies (4 RCTs and 10 NRSs) were evaluated as being effective regarding the work-related outcomes, while two more NRSs showed effects only between subgroups. However, only two studies were rated as having low risk of bias (35, 57). The effective studies were stratified according to the level of intervention and the type of the intervention. Three categories were compiled and presented below: (i) physical activity interventions aimed at changes in the workplace physical environment (n=3); (ii) nutrition and physical activity interventions aimed at changes at multi-levels of the workplace (organizational- and individual-level: n=4; environmental-, organizational- and individual-level: n=6); (iii) physical activity interventions aimed at changes at multi-levels of the workplace (organizational- and individual-level: n=2; environmental- and individual-level: n=1). The overview of effective interventions is summarized in Table 2.
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Physical activity interventions aimed at changes in the workplace physical environment
Three environmental-level intervention studies yielded statistically significant increases in workability and work performance. Ben-Ner, Hamann (30) RCT, which included 409 participants from a American financial service company, provided treadmills for 12months and measured work performance using objective and subjective measurements. Physical activity was also measured yielding statistically significant effect. The study was judged as having unclear risk of bias. Coffeng, Hendriksen (57) RCT, which included 412 participants from a Dutch financial service company, carried out a social and physical environmental intervention and measured its effectiveness on work performance using subjective measurement (IWPQ). The study was judged as having low risk of bias. Moreover, Gao, Nevala (34) NRS, which included 45 participants from a Finish University, provided sit-stand workstations and measured workability using subjective measurement (WAI). Occupational sedentary time and musculoskeletal comfort were also measured, yielding statistically significant effects. The study was judged as having moderate risk of bias.
Nutrition and physical activity interventions aimed at changes at multi-levels of the workplace
Three organizational- and individual-level intervention studies, which were conducted in USA, yielded statistically significant effects on absenteeism and productivity. These studies were judged as having moderate risk of bias. Aldana, Greenlaw (43) NRS, which included 6246 participants from education sector, conducted a 24-month wellness program and measured absenteeism using objective measurement. Lahiri and Faghri (40) NRS, which included 72 participants from 4 nursing home facilities, carried out a 16-week incentivized Behavioral Weight Management program and measured productivity using subjective measurement (WLQ). Weight loss was also measured, resulting in statistically significant effects. Schultz, Lu (50) NRS, which included 4189 participants from a manufacturing company, conducted a 36-month workplace health promotion program and measured absenteeism using objective measurement. An additional NRS, which included 543 participants from communication sector, conducted a 24-month health enhancement program and measured self-reported absenteeism and health risks. The study, which was judged as having moderate risk of bias, yielded statistically significant effects, however only between subgroups (60).
Six environmental-, organizational- and individual-level intervention studies yielded statistically significant reductions in absenteeism using objective measurements. Bertera (44) NRS, which was classified as no information, included 43888 participants from an American manufacturing company and conducted a 20-month multicomponent program. Braun, Bambra (45) NRS, which was judged as having moderate risk of bias, included 155 participants from British public and private sector and conducted a Better Health at Work Award program. Conrad, Riedel (46) included two NRSs which were conducted in USA at Blue Cross Blue Shield companies and were judged as having moderate risk of bias. The first studies included 1449 participants and received a 24-month “Go to health” program with screening and counseling, while the second study included 746 participants who received an 8-year “Alive and Well” program with health check. Jones, Bly (47) and Knight, Goetzel (48) NRSs conducted the same 36-month “Live for Life” program. The former included 1893 American workers from Johnson & Johnson Company and was judged as having moderate risk of bias while the latter included 4972 employees from Duke University and was classified as no information. An additional NRS, which included 14279 participants from an American manufacturing company, conducted a 24-month multicomponent program to measure self-reported absenteeism and behavioral risk factors. The study, which was judged as having moderate risk of bias, yielded statistically significant effects only between subgroups(52).
Physical activity interventions aimed at changes at multi-levels of the workplace
Two organizational- and individual-level intervention studies, which were conducted in Sweden, yielded statistically significant increases in workability and productivity. von Thiele Schwarz and Hasson (66) RCT, which included 177 participants from a large public dental health care organization, used a 12-month physical exercise intervention to measure workability using subjective measurement (WAI). The study was judged as having high risk of bias. Moreover, von Thiele Schwarz, Augustsson (65) NRS, which included 202 participants from 12 hospital units, used a 24-month integration program to measure workability and productivity using subjective measurement (WAI & HPQ, respectively). Health promotion, integration, kaizen and health were also measured, resulting in statistically significant effects. Due to insufficient data, the study was classified as no information. Furthermore, an environmental- and individual-level RCT, which included 200 female healthcare workers from 3 Danish hospitals, conducted 10-week workplace physical exercise with coaching sessions and ergonomic counseling to measure workability using subjective measurement (WAI). The study, which was judged as having low risk of bias, yielded statistically significant effects (35).