Keskin 2012.

Study characteristics
Methods	Type of study: prospective RCT. Condition and number of participants randomised: 88 pregnant women suffering from LBP with no previous history of LBP or lumbar pathology. Groups: active TENS (N = 22); exercise (N = 22); acetaminophen (N = 22); no‐Rx control (N = 22).
Participants	Demographics: N = 88, all female. Age: TENS group 29.1yrs ± 5.0; exercise group 30.7 ±4.3; acetaminophen 29.7 ± 4.2, control 29.2 ± 4.0. Setting: outpatient antenatal care unit, Turkey. Inclusion: uncomplicated pregnancy with LBP. Exclusion: history of Lumbar pathology pre‐pregnancy or pathology detected during physical examination; pain due to non‐musculoskeletal factors; declined to take part. Withdrawals/dropouts: TENS (N = 2); exercise (N = 3); acetaminophen (N = 3); control (N = 1).
Interventions	Where applied: on the painful lumbar region. Applied by: not stated. Waveform: not stated. Frequency: 120 Hz Pulse duration: 100 μs Pulse amplitude/Intensity: adjusted to produce a tingling sensation approx 2 to 3 times above the sensory threshold. Placebo TENS Group: N/A. Exercise group: completed a home exercise programme set by a physical therapist and including pelvic tilting, stretching for the lower extremity and mild isometric abdominal contractions x 10 of each per session, twice daily for 3 weeks. Acetaminophen group: one 500 mg paracetamol tablet 2 x daily for 3 weeks. Control Group: no Rx administered Electrodes: 4 surface electrodes 5 cm² Duration and frequency of Rx: duration not stated. 2 sessions weekly for 3 weeks. Device/manufacturer: Intelect TENS, Chattanooga Medical Supplies Inc., Taiwan). Adverse effects: discomfort using TENS and gastric effect with medication.
Outcomes	Pain outcome: VAS scores and Roland‐Morris Disability Questionnaire (RMDQ). ITT/per protocol analysis: not stated. Statistical analysis: median pre‐treatment VAS scores differed significantly between groups (P = 0.004; Kruskal‐Wallis test). These scores were significantly higher in the TENS group (P = 0.002; post‐hoc Mann‐Whitney) and acetaminophen groups (P = 0.009). Median pre‐treatment RMDQ scores were similar across all groups. At the end of the trial pain intensity had increased in control group (57%), and decreased in exercise group(95%). In acetaminophen and TENS groups 100% had a decrease in pain. All treatment groups showed a significant improvement in both VAS and RMDQ scores (P < 0.0001) using the Wilcoxon test. Differences in pre and post‐Rx VAS and RMDQ scores were significant in all treatment groups using Kruskal Wallis (VAS; P < 0.001; RMDQ, P < 0.001). This difference was caused by markedly higher scores in the TENS group (P < 0.001 for both comparisons; Mann‐Whitney test).
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation using sealed envelopes.
Allocation concealment (selection bias)	Low risk	Use of sealed envelopes.
Incomplete outcome data (attrition bias) All outcomes	High risk	Withdrawals and dropouts were reported but no information was included as to how the data was dealt with.
Source of funding bias	Low risk	No apparent funding bias.
Blinding (Participant)	High risk	No TENS placebo group so not possible to blind participants as to which group they were allocated to.
Blinding (Outcome Assessor)	Unclear risk	No details provided.
Sample Size	High risk	TENS (N = 22); exercise (N = 22); acetaminophen (N = 22); control (N = 22).