Pérez‐Palomares 2010.

Study characteristics
Methods	Two‐arm RCT Number analyzed/randomized: 125/135 Statistical analysis: ITT analysis; Student's t test and Mann–Whitney U test; power analysis not conducted Funding source: Aragonese Health Service (Spain) and Research Network on Preventive Activities and Health Promotion (Health Institute Carlos III) and Aragonese Health Science Institute Informed consents obtained; did not report ethical approval
Participants	Participant recruitment: referred by primary physicians from four primary healthcare centers in Spain Setting: NR Inclusion criteria: patients > 18 years old, with chronic LBP lasting at least 4 months, or less if it was recurring Exclusion criteria: 1) suspected or diagnosed fibromyalgia syndrome, structural lesions in the lumbar column, either at the disc level or on any other structure; 2) concomitant non‐pharmacological treatments (acupuncture, homeopathy), and any medical conditions or circumstances that in researcher's judgment might interfere with the results Age (mean ± SD): 45.9 ± 14.4 years Gender (female): 75% Pain duration ( > 1 ): 39.9% Pain intensity (mean): 6.0 (VAS, 0 to 10)
Interventions	1) GROUP 1: percutaneous electrical nerve stimulation therapy (PENS) Acupuncture points: eight acupuncture needles were inserted at the level of dermatomes from L2 to L5 bilaterally Depth: at a depth of 2 to 2.5 cm De Qi: NR Sessions: 9 sessions (30 min, 3/week for 3 weeks) Practitioner experience: NR 2) GROUP 2: Dry needling therapy Dry needling points: trigger points were diagnosed during the initial assessment and only those that remained active were treated in successive sessions. Depth: using needles of 0.30 × 40 mm with plastic guide tubes; did not report depth De Qi: elicited by fast‐in and fast‐out Hong's technique followed by spray and stretch technique. Each muscle was then passively stretched over three sequences, with vapocoolant spray applied. Treatment was carried out on the trigger points diagnosed during the initial assessment. Trigger points that remained active were treated in successive sessions. Sessions: 3 sessions in 3 weeks Practitioner experience: NR Co‐intervention: none reported Duration of treatment: 3 weeks Duration of follow‐up: immediately post‐treatment
Outcomes	1) Pain intensity: VAS (0 to 10) 2) Back‐specific function status: ODI (0 to 50) Assessment time: immediately post‐treatment Costs: NR Adverse effects: NR
Notes	Conclusion: The effectiveness of dry needling therapy was comparable to that of PENS. Language: English For results, see comparison 5.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random numbers table was used.
Allocation concealment (selection bias)	Low risk	"A third‐party investigator carried out the randomised distribution of both the sequence and the assignment."
Blinding of participants (performance bias) All outcomes	High risk	A pragmatic study; didn't mask participants
Blinding of personnel /care providers (performance bias) All outcomes	High risk	Not possible
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Assessor was blinded, but some outcomes were subjective.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Acceptable dropout rates: 3/67 in PENS and 7/68 in dry needing groups
Intention‐to‐treat‐analysis (attrition bias)	Low risk	Subjects in their assigned group who completed the treatment were included in the analysis.
Selective reporting (reporting bias)	Unclear risk	Results of VAS (pain; sleep) at 2 weeks after treatment were not reported.
Group similarity at baseline (selection bias)	Unclear risk	ODI baseline results were not given.
Co‐interventions (performance bias)	Unclear risk	Dry needling on trigger points group used additional vapocoolant spray on the pain reference zone.
Compliance bias (performance bias)	Unclear risk	Compliance not reported
Timing of outcome assessments (detection bias)	Low risk	Both groups had intermediate and final outcomes measured within the same week.
Other bias	High risk	Different numbers of included participants reported in the study