Study selection and characteristics
A flow diagram (Fig. 1) depicts the process that we employed in order to identify relevant articles. Out of 1442 initially retrieved studies, 7 studies were considered eligible for inclusion in this systematic review. Table 2 demonstrates the major characteristics of the 7 studies. Three of the included studies were RCTs[27–29], 2 were case-control studies[30, 31], 1 was cross sectional study[32] and 1 was a before-after treatment cohort study[33]. These studies were conducted in India[27, 33], Taiwan[30], China[29, 32], Turkey[31] and USA[28] and took place at university and hospital settings. Due to both small sample size from most included studies, but most importantly identification of serious heterogeneity and low quality of the eligible articles, a meta-analysis could not be performed. Hence, the respective results of each study are presented without being statistically processed.
Table 2
Characteristics of the studies included in the systematic review. For periodontal outcomes see main text. Abbreviations: COPD: chronic obstructive pulmonary disease; CP: chronic periodontitis; ER: emergency room; GOLD: global initiative for chronic obstructive lung disease; ICU: intensive care unit; IRR: incidence rate ratio; N/A: not applicable; OR: odds ratio; SGRQ: St. George Respiratory Questionnaire; SGRQ-A: American English modified SGRQ; SRP: scaling and root planning.
First author/year/
Country ref
|
Study design
|
Study population
|
Study
groups
|
Periodontal interventions
|
Outcomes/associations
|
Follow up period
|
Results
|
Das/2017/India 27
|
Randomized controlled trial
|
35 COPD patients with CP
|
-Periodontal treatment, n = 17
-No treatment, n = 18
|
Mouth scaling and root planning with hand instruments vs. no treatment
|
SGRQ
|
1 year
|
-Treatment group: improvement in the SGRQ “activity” subscore (53.68 ± 16.37 vs. 38.20 ± 13.18; p = 0.005)
-Control group: no change in SGRQ
|
Madalli/2016/India 33
|
Before-after treatment prospective cohort
|
30 COPD patients with CP
|
N/A
|
Supragingival scaling
|
-FEV1/FVC
-Sputum positivity for Porphyromonas gingivalis
|
3–5 months
|
-No significant improvement in FEV1/FVC
-No significant reduction in sputum positivity for Porphyromonas gingivalis
|
Shen/2016/Taiwan 30
|
Retrospective propensity-matched case-control
|
11124 COPD patients with CP
|
-Periodontal treatment, n = 5562
-No treatment, n = 5562
|
Subgingival curettage and root planning and/or invasive periodontal flap surgery vs. no treatment
|
-ER visits for COPD exacerbation
-Hospitalizations for adverse respiratory events
-ICU admissions
-All-cause mortality
|
-5 years from inclusion
-Occurrence of an adverse respiratory event
- Death
-Withdrawal from the insurance system
|
-ER visits per 100 person-years for COPD exacerbation: 2.54 ( treatment group) vs. 2.88 (control group); adjusted IRR of 0.86 (95% CI 0.78–0.94; p < 0.001)
-Hospitalizations for adverse respiratory events per 100 person-years: 2.75 (treatment group) vs. 3.65 (control group); adjusted IRR 0.74 (95% CI 0.69–0.80; p < 0.001)
-ICU admissions per 100 person-years: 0.66 (treatment group) vs 0.75 (control group); adjusted IRR 0.84 (95% CI 0.75–0.94; p < 0.01)
-All-cause mortality per 100 person-years: 1.81 (treatment group) vs. 2.87 (control group); adjusted rate ratio 0.57 (95% CI 0.52–0.62; p < 0.001)
|
Zhou/ 2014/ China 29
|
Randomized controlled trial
|
30 moderate-to-severe COPD patients
|
-Supragingival scaling, root planning and maintenance care (SRP group), n = 20
-Supragingival scaling and maintenance care (scaling group), n = 20
-No treatment (control group), n = 20
|
SRP vs. scaling vs. no treatment
|
-FEV1 (% predicted), FEV1/FVC
-Proportion of frequent exacerbations (≥ 2/year)
|
2 years
|
-Control group lung function compared to baseline:
---lower FEV1 at 2 years (56.3 ± 16.4 vs. 51.6 ± 18.4, p < 0.05)
--- lower FEV1/FVC at 1 and 2 years (0.55 ± 0.11 vs. 0.54 ± 0.11 vs. 0.53 ± 0.11; p < 0.05)
-SRP vs. control group:
---higher FEV1 at 1 year (55.9 ± 16 vs 53.6 ± 18.7; p < 0.05) and at 2 years (57.1 ± 19 vs. 51.6 ± 18.4; p < 0.05)
---higher FEV1/FVC at 1 year (0.59 ± 0.09 vs. 0.54 ± 0.11; p < 0.05) and at 2 years (0.57 ± 0.10 vs 0.53 ± 0.11; p < 0.05)
-Scaling vs. control group:
---higher FEV1 at 1 year (59.6 ± 17.1 vs. 53.6 ± 18.7, p < 0.005)
---higher FEV1/FVC at 2 years (0.56 ± 0.11 vs. 0.53 ± 0.11, p < 0.05)
-Proportion of frequent exacerbations in SRP vs. scaling vs. control group: 30% vs 15.8% vs. 66.7% ; p < 0.004
-Adjusted OR for frequent exacerbations:
---SRP group: 0.29, (95% CI 0.10–0.84; p = 0.02)
---scaling group: 0.004 (95% CI 0.003–0.64; p = 0.02)
-No differences in lung function and exacerbations between the 2 treatment groups
|
Kucukcoskun/2013/
Turkey 31
|
Prospective case-control
|
40 COPD patients with CP and ≥ 1 exacerbation in the previous year
|
-Periodontal treatment, n = 20
-No treatment, n = 20
|
Full-mouth scaling and root planning with hand instruments and ultrasonic devices
|
-Exacerbation frequency in 12 months
-Number of hospitalizations
|
12 months
|
-Exacerbation frequency per patient-year: 1.95 (treatment group) vs. 3.25 (control group)
-Exacerbation frequency decreased in treatment group (3 ± 1.83 vs 1.95 ± 1.46; p = 0.01) but remained unchanged in the control group (3.5 ± 4.62 vs 3.25 ± 3.35; p = NS)
-Hospitalizations increased from 4/year to 7/year in the treatment group and from 10/year to 12/year in the control group
|
Agado/2012/USA 28
|
Randomized controlled trial
|
30 COPD patients with CP
|
-Periodontal debridement with ultrasonic device, n = 10
- Periodontal debridement with hand instruments, n = 10
-No treatment, n = 10
|
Periodontal debridement
|
-SGRQ-A
-5-point Lickert scale of health status self-perception
− 7-item illness questionnaire
|
4–6 weeks
|
No improvement in SGRQ-A, health status self-perception and illness questionnaire post treatment
|
Liu/ 2012/China 32
|
Cross-sectional
|
392 COPD patients
|
-Frequent exacerbators
(≥ 2 events/year), n = 183
-Infrequent exacerbators (< 2 events/year),
n = 209
|
N/A
|
Periodontal/oral health and frequency of COPD exacerbations
|
N/A
|
Risk factors for frequent exacerbations:
-≤25 remaining teeth (adjusted OR 1.69, 95% CI 1.03–2.77; p = 0.04)
- <1 daily brushing frequency (adjusted OR 4.19, 95% CI 1.44–12.1; p = 0.008).
|
The diagnosis of COPD was based on GOLD criteria[27, 29, 31–33], medical records[28] and ICD-9 classification[30]. The diagnosis of COPD exacerbations was based on the GOLD criteria[29, 32], ICD-9 classification[30] and symptom worsening requiring treatment adjustment and/or hospitalization[31]. COPD exacerbations were reported by the patients[32], by the investigators[29] or were reported by the patient and confirmed by the investigator[31]; while 2 studies have also provided data on COPD exacerbations prior to periodontal interventions based on patients’ recall[29, 31]. The diagnosis of periodontitis was based on a mean attachment loss (MAL) ≥ 1.5 mm[28], a community periodontal index (CPI) > 3 and a loss of attachment (LOA) > 1[33], the presence of at least one site with a pocket probing depth (PPD) > 3 mm and periodontal clinical attachment loss (CAL) > 3 mm[29], the ICD-9 classification[30], on the American Academy of Periodontology Workshop 1999 guidelines[31, 34] and on oral/periodontal health indices[27, 32]. Quality of life was assessed with the Saint George Respiratory Questionnaire (SGRQ) in 2 studies[27, 28]. The effect of periodontal treatment on lung function variables was investigated in 2 other studies[29, 33].
Periodontal therapy was established through scaling and root planning using hand instruments (1 study)[27], supragingival scaling, hygiene instructions and preprocedural antibiotics (1 study)[33], subgingival curettage, root planning and periodontal flap surgery (if needed) (1 study)[30], oral hygiene instructions, supra- and subgingival scaling using hand instruments and ultrasonic devices (3 studies) [28, 29, 31]. In another study information about the frequency of previous supragingival scaling procedures was obtained by interview[32] .
Risk of bias within studies
Risk of bias for RCTs was judged as “some concerns” in one trial[28] and “high” in two trials[27, 29]. With regard to the rest of the studies, serious methodological limitations were found for two studies[32, 33] and moderate for another two[30, 31]. Risk of bias summary plots are depicted in Figs. 2 and 3.
Results Of Data Synthesis
Quality of life
Two studies[27, 28] evaluated the effect of periodontal therapy on quality of life. Das et al.28 randomized 35 COPD patients (diagnosed according to the GOLD spirometric criteria) to receive either periodontal treatment (treatment group, n = 18) or no treatment (control group, n = 17). Interventions included full-mouth scaling and root planning with hand instruments as well as oral hygiene instructions, while the effect of periodontal therapy on quality of life was assessed with the SGRQ score. All patients were reassessed at 1-year post-treatment for significant changes in periodontal and oral parameters and in SGRQ scores. With respect to the intervention group in this study significant improvements were observed in the Oral Hygiene Index-Simplified (OHI-S), Gingival Index (GI) and CAL, but not in PPD, while no differences in any of the appraised parameters were noted in the control group. The SGRQ “activity” subscore significantly improved in the treatment group post treatment (53.68 ± 16.37 vs. 38.20 ± 13.18; p = 0.005), but no differences in any of the SGRQ subscores were observed in the control group. At the end of the 1-year follow-up period, no differences were noted in the SGRQ subscores between the two groups with the exception of the “activity” subscore which was significantly better in the intervention group (38.20 ± 13.18 vs. 56.48 ± 18.31; p < 0.01). Agado et al. [28] randomized 30 COPD patients (recruited from medical databases) with chronic periodontitis (MAL ≥ 1.5 mm) into periodontal therapy with ultrasonic instrumentation (n = 10), periodontal therapy with hand instruments (n = 10) or no treatment (n = 10) for a follow-up period of 4–6 weeks; periodontal treatment was completed when all clinically detectable deposits had been removed. The effect of periodontal therapy on quality of life was evaluated with the American English modified SGRQ score (SGRQ-A), while patients graded their perception of health status on a 5-point Likert scale from “very poor” to “very good”. In addition, all participants provided a yes/no response to a customary made 7-item “illness questionnaire” which interrogated respiratory or other illness within the previous 4 weeks, physician visits, antibiotic use, use of respiratory medications, respiratory problems after dental care and avoidance of dental care due to respiratory ailments. All questionnaires were issued by an investigator blinded to the type of intervention. At the end of the follow-up period no significant difference was noted between the 3 groups in SGRQ-A total scores, self-assessment of health scores and “illness questionnaire” and no improvement between pre- and post-test. However, each group showed a significant improvement in the SGRQ-A “activity” subscore but with no interactions between groups.
Lung function
Two studies[29, 33] evaluated the effect of periodontal therapy on lung function. Madalli et al.29 conducted a before-after treatment prospective cohort study of 30 COPD patients with periodontal disease to investigate the effect of periodontal treatment on FEV1/FVC variables. COPD diagnosis was based on the GOLD spirometric criteria and the diagnostic criteria for periodontal disease included a CPI score ≥ 3 and a LOA score ≥ 1. Interventions included supragingival scaling and oral hygiene instructions and all patients were re-assessed after 3–5 months. This study observed no significant changes in CPI and LOA scores, while no significant improvement in FEV1/FVC was also noted (48.08 ± 12.01 vs. 51.25 ± 12.29; p = NS). Zhou et al.27 randomized 60 moderate-to-severe COPD patients (diagnosed according to the GOLD criteria) into scaling, root planning and maintenance care (SRP group, n = 20), supragingival scaling alone and maintenance supragingival scaling (scaling group, n = 20) or no treatment (control group, n = 20). Periodontal disease was considered based on the presence of at least one site with a PPD > 3 mm and a CAL > 3 mm. All patients were re-assessed for changes in periodontal variables, namely PPD, CAL, bleeding index (BI) and plaque index (PI) at 6 months, 1 year and 2 years, while lung function variables (FEV1, FEV1/FVC) were re-evaluated at 1 year and 2 years. This trial observed significant improvements in both treatment groups at 6 months, 1 year and 2 years for all the appraised periodontal parameters, whereas no improvements were noted in the control group; all periodontal variables were worse in the control group as compared to each of the treatment groups at any of the investigated time points. With respect to the lung function variables, when compared to baseline, the control group exhibited a significant decrease in FEV1 (% predicted) at 2 years (56.3 ± 16.4 vs. 51.6 ± 18.4, p < 0.05) and in FEV1/FVC at 1 and 2 years (0.55 ± 0.11 vs 0.54 ± 0.11 vs 0.53 ± 0.11, respectively; p < 0.05). When compared to the control group, the SRP group showed significantly improved levels of FEV1 (% predicted) and FEV1/FVC at 1 year (55.9 ± 16 vs 53.6 ± 18.7 and 0.59 ± 0.09 vs. 0.54 ± 0.11, respectively; p < 0.05) and at 2 years (57.1 ± 19 vs. 51.6 ± 18.4 and 0.57 ± 0.10 vs 0.53 ± 0.11, respectively; p < 0.05). Likewise, when the scaling group was compared to controls, it exhibited a significantly higher FEV1 (%predicted) at 1 year (59.6 ± 17.1 vs. 53.6 ± 18.7, p < 0.005) and FEV1/FVC at 2 years (0.56 ± 0.11 vs. 0.53 ± 0.11, p < 0.05). No differences in lung function were observed between the two treatment groups at any of the abovementioned time points.
COPD exacerbations
Four studies[29–32] evaluated the effect of periodontal therapy on the frequency of COPD exacerbations. In the previously mentioned RCT by Zhou et al, COPD exacerbations post-randomization were defined according to the GOLD criteria and their frequencies were assessed at 6 months, 1 year and 2 years, while their frequency during the last year prior to randomization was self-reported by the patients; patients with ≥ 2 events /year were defined as “frequent” exacerbators. At 2 years, the SPR and the scaling groups showed a lower proportion of “frequent” exacerbations as compared to controls (30% vs 15.8% vs. 66.7%, respectively; p < 0.004). In a multivariate logistic regression model, the calculated OR for “frequent” exacerbations was 0.29 (95% CI 0.10–0.84; p = 0.02) for the SRP group and 0.004 (95% CI 0.003–0.64; p = 0.02) for the scaling group after adjusting for age, gender, body mass index (BMI) and baseline frequency of exacerbations. No differences were noted in the frequency of COPD exacerbations between the two treatment groups.
Shen et al.[30] conducted a population-based, retrospective case-control study based on the Taiwan National Health Insurance claims data. COPD and periodontal disease diagnosis, periodontal interventions and adverse respiratory effects were identified based on the database’s ICD-9 classification. The study population consisted of 5562 COPD individuals that received periodontal therapy and 5562 propensity-matched controls. All subjects were followed up to a maximum of 5 years or until death, occurrence of an adverse respiratory event or withdrawal from the insurance system. Periodontal interventions included supragingival scaling and root planning as well as periodontal flap surgery, depending on the severity of the disease. The primary outcomes included emergency room (ER) visit and hospitalization rates following acute COPD exacerbation, pneumonia or acute respiratory failure. Overall, all types of adverse respiratory events were less frequent in the treatment group as opposed to the control group. After adjusting for confounders, including age, gender, residential area, occupation, income and comorbidities, the ER visit rate per 100 person-years for COPD exacerbation was 2.54 for the treatment group vs 2.88 for the control group, for an adjusted incidence rate ratio (IRR) of 0.86 (95% CI 0.78–0.94; p < 0.001).
Kucukcoskun et al[31] conducted a prospective case-control study consisting of 40 patients with COPD, diagnosed according to the GOLD criteria with a history of ≥ 1 exacerbation during the previous year and with moderate-to-severe chronic periodontitis based on the 1999 American Academy of Periodontology Workshop guidelines. COPD exacerbation was defined as a worsening in the baseline respiratory symptoms lasting at least 2 days and necessitating oral steroids and antibiotics (moderate exacerbation) or hospitalization (severe exacerbation). Patients were allotted to periodontal treatment (oral hygiene, full mouth scaling and root planning with hand instruments and ultrasonic devices completed over 3 visits, n = 20) or no treatment (n = 20) according to their access to periodontal services. Exacerbations were self-reported by the patients and confirmed by the investigator, while the number of exacerbations and hospitalizations during the last year before enrollment was also registered. Periodontal procedures were performed by a dentist blind to the study design and COPD severity and all patients were re-evaluated at 6 and 12 months. With respect to the periodontal parameters, when compared to baseline, the treatment group exhibited significant improvements in BP, GI, PPD and CAL at 6 months; at 12 months this improvement remained significant only for CAL. On the other hand, in the control group most of the periodontal parameters showed significant deterioration at 6 (GI, PPD, PI and CAL) and 12 months (GI, PPD, and CAL). The frequency of exacerbations per patient-year was 1.95 events in the treatment group vs. 3.25 events in the control group (p = 0.01). After 1 year of follow-up, exacerbation frequency, was significantly reduced in the treatment group (3 ± 1.83 vs 1.95 ± 1.46; p = 0.01) but remained unchanged in the control group (3.5 ± 4.62 vs. 3.25 ± 3.35; p = NS).
Liu et al.[32] conducted a cross-sectional study investigating the role of periodontal health on the frequency of COPD exacerbations. The diagnosis and definition of COPD exacerbation were based on GOLD criteria. Overall, 392 COPD patient were assessed for the presence and severity of periodontal disease and were interviewed about oral health habits, history of dental visits and supragingival scaling procedures during the last 12 months. Periodontal examination was conducted by an investigator blinded to COPD severity. The patients also provided information about the frequency of exacerbations during the previous 12 months with patients with < 2 events classified as “infrequent” exacerbators (n = 209), whereas those with ≥ 2 events considered “frequent” exacerbators (n = 183). In a multivariate logistic regression model adjusted for age, gender, BMI and smoking, ≤ 25 remaining teeth ( adjusted OR 1.63, 95% CI 1.01–2.61; p = 0.045), a PI > 2 (adjusted OR 1.93, 95% CI 1.09–3.42; p = 0.02) and < 1/day brushing frequency (adjusted OR 4.5, 95% CI 1.6–12.7; p = 0.004) were the independent predictors of “frequent” exacerbations. When COPD severity and dyspnea scores were additionally considered in the model, this association was still significant only for fewer remaining teeth (adjusted OR 1.69, 95% CI 1.03–2.77; p = 0.04) and lower daily brushing frequency (adjusted OR 4.19, 95% CI 1.44–12.1; p = 0.008).
Secondary outcomes
a. Periodontal outcomes
Regarding the periodontal outcomes, the appraised parameters presented amelioration or no change. In the RCT by Das et al, periodontal therapy with full-mouth scaling and root planning with hand instruments combined with oral hygiene was associated with improvements in OHI-S (3.38 ± 1.27 vs. 2.32 ± 1.21; p = 0.018), GI (1.79 ± 0.54 vs. 1.19 ± 0.47; p = 0.001) and CAL (4.17 ± 0.75 vs. 3.26 ± 0.90; p = 0.003) at 1 year post-treatment[27]. In the case-control study by Kucukcoskun et al full mouth scaling and root planning with hand instruments plus oral hygiene effected improvements in BOP% (58 ± 28 vs. 47 ± 19; p < 0.01), GI (1.52 ± 0.37 vs. 1.34 ± 0.23; p < 0.01), PPD (2.70 ± 0.66 vs. 2.39 ± 0.41; p < 0.01) and CAL (3.73 ± 1.16 vs. 3.39 ± 1.01; p < 0.01) at 6 months, as compared to baseline; at 12 months CAL continued to show significant improvement with respect to its baseline value (3.73 ± 1.16 vs. 3.52 ± 1.02; p < 0.01)[31]. Likewise, in the RCT by Zhou et al, all assessed periodontal parameters (i.e. PD, CAL, BI, PI), exhibited significant improvements for both the SRP and the scaling group at any time point (6 months, 1 year, 2 years)[29]. On the contrary, supragingival scaling plus oral hygiene did not result in any improvement in CPI and LOA scores (4 ± 0.51 vs 4.0 ± 0.48 and 2 ± 0.37 vs 2 ± 0.37, respectively; p = NS) after 3–5 months as reported by Madalli et al. Radiographic alveolar bone loss and levels of inflammatory biomarkers were not assessed by any of the included studies.
b. Periodontal pathogens, hospitalizations, mortality and comorbidities.
In the study by Madalli et al.[33] the proportion of COPD patients with a positive sputum sample for Porphyromonas gingivalis decreased from 14/30 to 8/30 at 3–5 months post treatment, although this finding was not significant. In the case-control study by Kucukcoskun et al [31], 1-year hospitalization rate post-treatment increased as compared to the previous year both in the treatment (from 4 to 7 events) and in the control group (from 10 to 12 events). On the other hand, in the retrospective case-control study by Shen et al.[30] the respective hospitalization rates per 100 person-years for all types of adverse respiratory events were 2.75 for the treatment group vs. 3.65 per 100 person-years for the control group (adjusted IRR 0.74, 95% CI 0.69–0.80; p < 0.001). In addition, ICU admissions per 100 person-years were 0.66 for the treatment group vs. 0.75 for the control group (adjusted IRR 0.84, 95% CI 0.75–0.94; p < 0.01), while the all-cause mortality rate was 37% lower for those treated for periodontal disease (adjusted rate ratio 0.57, 95% CI 0.52–0.62; p < 0.001). No study reported on the effects of periodontal treatment on the prevalence and severity of COPD-associated comorbidities.
Risk of bias across studies
The quality of evidence for all outcomes ranged from moderate to very low (Table 3). The main reason for downgrading the quality of evidence pertained to the inclusion of non-randomized studies with serious methodological issues that most probably introduce bias and to the imprecision of estimates due to narrative synthesis. This means that further research in terms of well-designed studies is very likely to have an important impact, which is likely to change our current estimates of effect.
Table 3
Summary of findings table according to GRADE approach
Periodontal therapy compared to no periodontal therapy in patients with PD and COPD
|
Patient or population: Patients with PD and COPD
Setting: University clinics and Hospitals (India, Taiwan, China, Turkey and USA)
Intervention: periodontal therapy
Comparison: no periodontal therapy
|
Outcome
№ of participants
(studies)
|
Impact
|
Certainty
|
What Happens with periodontal therapy
|
Exacerbations of COPD
assessed with:
Exacerbation frequency
№ of participants: 11616
(4 studies)
|
In one study acute exacerbation rate was 2,54 vs 2,88 per 100 person-years for emergency room use, [adjusted IRR = 0.86 (95% CI 0.78–0.94, p < 0,001)] and 1.36 vs 1.71 per 100 person-years for hospitalizatios, [adjusted IRR = 0.78 (95% CI 0.72–0.85, p < 0,001)]
In another proportion of frequent exacerbations was statistical significantly (p < 0.004) lower in periodontal therapy group at 2-years follow up.
In the third study frequency of exacerbations was 1.95 per patient-years compared to 3.25 in the control group (p = 0.01).
In the last study, although supragingival scaling < 1time/year was associated with higher proportion of patients with frequent exacerbations, in the adjusted model no statistical significance was obtained (OR = 2.23, 95% CI: 0.58–8.59, p = 0.24)
|
⨁⨁⨁◯
MODERATE a,b,c
|
Probably reduces frequency of exacerbations of COPD
|
Quality of life
assessed with:
SGRQ
follow up: range 4 weeks to 1 years
№ of participants: 65
(2 studies)
|
In one study SGRQ domain scores were lower in study group at one year follow up(p < 0.05 only for activity domain score)
In the another study SGRQ and illness Questionnaire responses showed no significant difference between groups
|
⨁◯◯◯
VERY LOW c,d
|
Too heterogenous response
to synthesize across studies
|
Lung function
assessed with:
FEV1, FEV1/FVC
follow up: range 3 months to 2 years
№ of participants: 116
(2 studies)
|
In one study, although FEV1/FVC mean value increased, no statistical significance was obtained
In the another study, FEV1 increased statistical significantly in one year follow up for both periodontal therapy groups(p = 0.03), but only for SRP group in two years follow up. FEV1/FVC increased statistical significantly in two years follow up for both periodontal therapy groups(p = 0.02), but only for SRP group in one year follow up (p = 0.04)
|
⨁◯◯◯
VERY LOW c,e
|
Too heterogenous response
to synthesize across studies
|
Explanations
a. Downgraded by one level for bias due to the inclusion of non-randomized study with high risk of bias
b. Inconsistency attributed to the fact that exacerbation frequency was expressed by different values(exacerbations per 100persons-years, exacerbations per patient-year, proportion of exacerbation, proportion of patients with exacerbations) was not serious to downgrade the quality of evidence for this outcome
c. Narrative synthesis was conducted. Estimates are not precise.
d. Downgraded by two levels for bias, because one of the two included studies is non-randomized with high risk of bias and serious limitations
e. Included studies are judged as "high" and "serious" risk of bias
|