Patil 2018.

Study characteristics
Methods	Randomized controlled parallel‐group trial.
Participants	88 nurses with chronic LBP of whom 82% had non‐specific LBP. Settings: tertiary care teaching hospital (the workplace of the nurses). Location of yoga classes not described. Country: India. Recruitment: "nurses were screened and referred by the orthopedician" however flow chart (Figure 1) stated "self and physician referred [sic]." Inclusion criteria: female nurses with diagnosis of non‐specific LBP, lumbar spondylosis, or intervertebral disk prolapse; LBP for ≥ 3 months as diagnosed by an orthopedician and knowledge of English, Hindi, and Kannada language. Exclusion criteria: pain due to organic causes such as infective and inflammatory conditions, metabolic disorders, and post‐traumatic condition; degenerative disorders of muscles; comorbid cardiac or neuropsychiatric illness; history of major surgery or injury; pregnant women; neurologic complications of chronic LBP.
Interventions	Yoga group: (n = 44) 6 weeks of 60‐min yoga classes provided 5 days/week. Home practice: not mentioned. Exercise group: (n = 44) 6 weeks of 60‐min physical exercises provided 5 days/week. Common interventions: none described. Co‐interventions: no mention of included or excluded co‐interventions. Duration and follow‐up: interventions provided for 6 weeks and follow‐up finished at end of intervention.
Outcomes	Quality of life – mental (Psychological health scale of WHOQOL‐BREF questionnaire English and Keralan version at 6 weeks. Quality of life – physical (physical health scale of the WHOQOL‐BREF) at 6 weeks. Other outcomes collected: Social Relationships scale of the WHOQOL‐BREF, Environmental Health scale of the WHOQOL‐BREF.
Notes	Adverse events: no mention of assessment of adverse events. Measurement of expectations or treatment preferences at baseline: none. Funding: report stated there was no financial support or sponsorship.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Comment: used random number generator (www.randomizer.org).
Allocation concealment (selection bias)	Unclear risk	Comment: no mention of allocation concealment.
Blinding of participants	High risk	No blinding.
Blinding of personnel/providers	High risk	No blinding.
Blinding of outcome assessors	High risk	Comment: participants not blinded and outcomes based on self‐report.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "There were no dropouts in the study."
Selective reporting (reporting bias)	Unclear risk	Comment: no protocol available.
Group similarity at baseline	Low risk	Quote: "Participants in the two groups did not differ much in relation to their age, education, or duration of illness between the groups as shown in Table 1." Quote: "There was a no significant difference between the yoga and control groups at the baseline for all the four domains of WHOQOL­BREF: (a) physical (P = 0.296), (b) psychological (P = 0.987), (c) social (P = 0.661), and (d) environmental (P = 0.904) as shown in Table 5."
Co‐interventions	Unclear risk	Comment: no mention of medication use at baseline, or any permitted or disallowed co‐interventions during study.
Compliance	Unclear risk	Comment: no mention of compliance or adherence.
ITT analysis	Unclear risk	Comment: no mention of ITT analysis.
Timing of outcome assessments	Low risk	Quote: "Data were taken at the same time of the day on the 1 and 43 day. Orientation to yoga program was given to the participants for 3 days, and then on the next day, predata collection was done after satisfactory performance. WHOQOL­BREF assessments were done on day 1 and day 43 (after 6 weeks)."
Other bias	Low risk	No other biases identified.