Dehghan 2016.

Methods	Randomised parallel group study carried out among private dental practitioners in Tehran, Iran
Participants	Inclusion criteria: dentists residing in Tehran, willing to fully participate in the study, and avoid the use of pain relievers during the study Exclusion criteria: Female dentists who were pregnant while the study was being conducted, and history of any spine surgery Age at baseline: 39.82 ± 4.61 (mean ± SD) years in the intervention group, and 40.01 ± 4.12 years in the control group Sociodemographics: not reported Total number: 102 Number randomised ‐ intervention group 50; control group 52 Number evaluated ‐ intervention group 50; control group 52 At baseline, the number of participants free from symptoms in the control (82%) and intervention (84%) groups for thigh MSDs; free from foot MSDs in the control (75%) and intervention (76%) groups. Less than 75% participants were free from MSDs in knee, back, wrist, arm, shoulder, and neck,
Interventions	The study compared an 8‐week multi‐faceted ergonomic intervention program which included modification in both operator factors (work posture, chair position, method of instrument usage), and office design factors (workstation layout, set‐up of operatory and chairs, delivery systems) with a control group, which did not receive any intervention. Intervention consisted of: 1. Knowledge and training about ergonomics: Training sessions provided to participating dentists at the start of the multi‐faceted ergonomic program, which covered the basic ergonomic principles, ergonomic risk factors in dental occupation, and intervention components of the ergonomic program. 2. Workstation modification: At this stage, keeping in mind the risk factors in the dental occupation, participants were instructed on how to ergonomically modify their working postures in different situations at the workplace. For example, the correct working posture and correct alignment of the equipment was explained to the dentists. 3. Training and surveying ergonomics at the workstation: At this stage, working conditions were evaluated during the working shift for each dentist, and ergonomic risk factors associated with workstations were identified. To mitigate the risk factors, active discussions and workstation modifications were carried out. 4. A regular exercise program: A physiotherapist introduced exercises involving stretching movements targeting the neck, shoulder, waist, and bottom. These exercises continued regularly during the study. Participants were also asked to note their daily sports activities in the logbook.
Outcomes	The General Nordic Questionnaire of musculoskeletal symptoms was used to assess MSDs at baseline, 3 months, and 6 months, in various locations of the body, such as knees, thighs, back, wrist, arm, shoulder, neck, and feet. The text of the article stated that paired t‐test was used to compare differences in prevalence; data tables stated that repeated measure ANOVA was used to determine statistical significance. Only outcomes for thighs and feet were used in the current review, since all other sites had more than 75% participants with MSD.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomly divided into 2 groups". Did not describe the method of randomisation.
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Work ability was assessed by using self‐reported outcomes. Essentially, the participants were also the outcome assessors, thus blinding to prevent detection bias was not feasible. It remained unclear how self‐reporting would have influenced the subjective outcome reporting, either favourably or unfavourably, hence, we rated this as unclear risk of bias.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All 102 participants completed the study.
Selective reporting (reporting bias)	Low risk	All outcomes stated in methods reported in results
Other bias	High risk	Two components were assessed in this item – compliance and statistical tests used. Compliance was neither measured nor reported, if measured. There were errors in the statistical tests used to assess data in this study. The text stated paired t‐test, the graphs stated repeated measure ANOVA were used to determine statistical significance. As this was a parallel design RCT, which involved independent groups, the correct tests should have been Chi² or logistic regression for categorical outcome variables (as per outcomes measured in this study, in which they measured prevalence of musculoskeletal, which required a yes or no response) or independent t‐test for numerical outcome response. Paired t‐test and repeated measure ANOVA are best used in within groups instances; the outcome response in this study (prevalence of musculoskeletal disorder) was dichotomous. This inappropriate use of statistical test may have resulted in serious errors and statistically significant results where none existed, thus making us classify this as high risk of bias.