Darwood 2008.

Study characteristics
Methods	Study design: prospective, RCT Country: UK Setting/Location: hospital Source of funding: Promed (Bluntisham, UK) ‐ sponsor had no input in study design, data collection, data analysis/interpretation or preparation of the manuscript Intention‐to‐treat analysis: no (one surgery participant had EVLT1 and was followed up in the laser cohort)
Participants	No of participants randomised: total n = 118 participants (136 legs) (EVLT1 49 legs; EVLT2 42 legs; HL/S 45 legs) No of participants analysed: total n = 95 participants (114 legs) (EVLT1 42 legs; EVLT2 29 legs; HL/S 32 legs) Exclusions post‐randomisation: seven participants (11 legs) withdrew from the study as not happy with their treatment allocation. Six participants were treated outside the study interval and were also excluded. Losses to follow‐up: total n = 11 participants (EVLT1 5 legs; EVLT2 4 legs; HL/S 2 legs) Age ‐ median years (IQR): EVLT1: 42 (30.5 ‐ 54.5); EVLT2: 52 (35 ‐ 59); HL/S: 49 (38.5 ‐ 57.5) Sex ‐ F/M : EVLT1: 22/16; EVLT2: 16/11; HL/S: 16/14 No bilateral limbs randomised: EVLT1 9, EVLT2 6, HL/S 4 Inclusion criteria: > 18 years of age; symptomatic varicose veins and primary SFJ incompetence (confirmed on DUS) Exclusion criteria: on warfarin; unsuitable for EVLT (tortuous GSV, large incompetent anterior accessory saphenous vein)
Interventions	Treatment(s): 2 EVLT techniques: EVLT1: 12 W power with 1s laser pulses and 1s intervals between pulses; laser fibre withdrawn 2 ‐ 3 mm during intervals EVLT2: 14 W continuous power and continuous laser withdrawal Both procedures performed with EVLT; Diomed, Andover, Massachusetts, USA Control: HL/S ‐ open surgery; SFJ ligation, GSV stripping to knee level and multiple phlebectomies of varicosities Duration: follow‐up at 1, 6, 12 weeks and 1 yr after treatment
Outcomes	Primary outcomes: abolition of reflux in the treated segment of GSV and improvement in disease‐specific QoL 3 months after treatment Secondary outcomes: post‐procedure pain, time to return to normal activity and work, cosmesis, overall satisfaction at 3 months Recurrence definition: study authors state "This short‐term study was not designed to assess recurrence rates"
Notes	Participants with bilateral veins were randomised once and received the same treatment simultaneously on each leg. Study authors reported difficulty recruiting participants to the study. They did not meet the sample sizes for their study groups to make their desired power calculations. Statistical tests for equivalence were therefore not performed.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Block randomisation using sealed envelopes. Randomisation was stratified by consultant 'to allow for any minor variations in technique'. No clear details on how this stratification was achieved
Allocation concealment (selection bias)	Low risk	Used sealed envelopes
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not possible to blind investigators or participants. No blinding of participants
Blinding of outcome assessment (detection bias) All outcomes	High risk	No blinding of assessors
Incomplete outcome data (attrition bias) All outcomes	Low risk	Missing data are balanced across the groups, with similar reasons given for the missing data
Selective reporting (reporting bias)	Low risk	The pre‐specified outcomes in the study protocol were reported in the pre‐specified way
Other bias	Unclear risk	Study authors reported difficulty recruiting participants to the study. They declared that their sample sizes were insufficient to permit statistical testing for equivalence One participant randomised to surgery underwent laser, and was followed up in the laser cohort showing no analysis of intention to treat Some participants received bilateral treatment. Study authors stated these participant would receive the same treatment on both limbs. These participants who received bilateral treatment were not stratified in the results Some outcome measures can be affected by bilateral treatment e.g. QoL, pain, time to return to work etc. therefore introducing a bias Participants who underwent laser did not have concomitant mini‐phlebectomies. This adds a potential confounding bias when analysing results of post‐operative pain, time to return to work etc.