Soukup 1999.

Methods	Randomised, controlled, and intention‐to‐treat basis. No reports of concealed allocation and blinding.
Participants	Most subjects were recruited from outpatient medical, chiropractic and physiotherapy practices in south‐east Norway. Supervised Mensendieck arm: total 77 participants were randomised into a Mensendieck exercise group (N = 39). 12 month follow‐up: During the 12 month of follow‐up treatment, 5 participants dropped out. Analysis is performed on N = 34. 3‐year follow‐up: the analysis included Mensendieck group, N = 31. Control group for both intervention and all follow‐ups was (N = 38). During the 12 month of follow‐up treatment, 3 participants dropped out. Dropouts are discussed, but excluded from the analysis. Analysis is performed on N = 35. Inclusion criteria: men and women 18 to 50 years old who had experienced one or more episodes of pain localised to the lumber region, with or without pain radiation to the lower extremities. It was required that patients had finished their treatment for LBP episode prior to enrolment. Exclusion criteria: back surgery, pregnancy, specific diseases, and spinal fracture.
Interventions	Post‐treatment Mensendieck exercise group: Subjects received exercises and biomechanical/ ergonomic education in 20 sessions of 60 minutes each for 13 weeks, twice a week for first 7 weeks and once a week for the last 6 weeks. Each session was consisted of warm‐up and stretching exercises for 15 minutes, a combination of ergonomic education and pelvic, hip, back, and abdominal exercises for 35 minutes, and stretching and relaxation exercises for 10 minutes. Control group: Subjects did not receive any attention but were free to choose other treatments for LBP or engage in other physical activities. Apart from the follow‐up assessments, the group did not receive any further attention or information.
Outcomes	Number of subjects with recurrent LBP, number of recurrences of LBP, time to LBP recurrences, number of subjects with sick leave due to LBP, and days of sick leaves due to LBP.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Subjects were randomised in blocks of six to maintain a consistent class size.
Allocation concealment?	Unclear risk	Unclear.
Blinding? All outcomes	High risk	No blinding reported.
Incomplete outcome data addressed? All outcomes ‐ drop‐outs?	Low risk	No significant difference was found between the two groups with regard to drop‐out rate and time until drop out (5 in intervention and 3 in control).
Incomplete outcome data addressed? All outcomes ‐ ITT analysis?	High risk	No ITT analysis.
Similarity of baseline characteristics?	Low risk	No statistically significant difference between the intervention and control group was found in baseline characteristics.
Co‐interventions avoided or similar?	Low risk	No exercise was given in control group.
Compliance acceptable?	Low risk	Average compliance: 85%; Range: 65‐100%.
Timing of outcome assessments similar?	Low risk	Outcomes were measured at baseline and 1 year.