Ulger 2017.

Study characteristics
Methods	Study design: RCT (NCT02696057) Setting: Turkey, healthcare Exercise groups: 1 Comparison groups: 1
Participants	Number of participants: 144 (E1 = 72, C1 = 72) Chronic LBP duration: Not specified (not specified) Neurological/radicular symptoms: No participants Mean age (years): 42 Sex (female): 59%
Interventions	Exercise Group 1 (E1): Spinal stabilisation exercises: various exercises focussed on contracting the transverse abdominus and multifidus muscles; type = core strengthening; duration = 6 weeks; dose = low; design = individualised; delivery = individual; additional intervention = none Comparison Group 1 (C1): Other conservative treatment (manual therapy)
Outcomes	Core outcomes reported: Pain (Visual Analogue Scale); function (Oswestry Disability Index); HRQoL (36‐Item Short Form Survey) Follow‐up time periods available for syntheses: 6 weeks (short)
Notes	Conflicts of interest: None to declare Funding source: Not reported Other: Information modified for author contact
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was performed by drawing lots among the patients who had applied for the treatment and met the participation criteria; method also applied block randomisation.
Allocation concealment (selection bias)	High risk	No information on treatment allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	1. Patients were not blinded because of the differences in interventions; only statistician and outcome assessor (for non‐patient‐reported outcomes) were blinded; 2. Unlikely that patients could cause deviations from treatment protocols, as they had to be applied by trained physiotherapists
Blinding of care provider (performance bias)	Low risk	1. Care providers could not be blinded to allocation because they were delivering interventions; 2. Different therapists for each treatment
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	1. Assessors of outcomes of interest (pain and disability) were patients, and thus were not blinded to allocation due to the distinct nature of the treatment groups; 2. Pain and functional questionnaires are subjective, and responses could be altered by awareness of intervention; 3. The two treatment groups had reasonably similarly intense intervention, and thus there was not a strong indication to a non‐expert as to which one would be more effective.
Incomplete outcome data (attrition bias) All outcomes	Low risk	1. 31 "excluded" ...failed to "make time" and "show up", 20%; 2. Patients were excluded from the analysis; 3. Increased low back pain and decreased function can cause missing outcome; 4. 15 versus 16
Participants analysed in group allocated (attrition bias)	Low risk	1. Appeared that all patients were analysed according to their allocated treatment group (intention‐to‐treat)
Selective reporting (reporting bias)	Low risk	1. Protocol (NCT02696057): all analysis reported as described in protocol and article methods section
Groups similar at baseline (selection bias)	High risk	Age, sex body mass index, Oswestry and most Quality of Life subscales were not significantly different at baseline between treatment groups, however, visual analogue scale was notably different at baseline between groups.
Co‐interventions avoided or similar (performance bias)	Low risk	Patients with ongoing pharmaceutical medication were excluded from the study (avoiding co‐interventions); history of physiotherapy was recorded but not reported.
Compliance acceptable in all groups (performance bias)	Low risk	No reporting of compliance
Timing of outcome assessment similar in all groups (detection bias)	Low risk	1. Within each outcome, all participants were measured with the same tool and at the same time point; 2. Visual Analogue Scale (for pain) and Oswestry Disability Index (for disability) are well‐validated tools in the context of low back pain.
Other bias	Low risk	Appeared free from other sources of bias