Methods	RCT
Participants	204 women with entire squamo-columnar junction visible CIN 1 on 2 biopsies 3-6 months apart, CIN 2 or 3 not extending 3 mm into crypts No extension onto vagina or lesion or 12.5 mm into canal
Interventions	Cryotherapy Laser ablation
Outcomes	Operators impression of significant peri-operative bleeding >25cc Women’s subjective opinion of peri-operative pain (mild, moderate severe, Severe being that the woman would not consider the treatment again) Women’s subjective opinion of post-operative discomfort, heavy discharge, bleeding (none, mild, moderate, severe) Post operative cervical stenosis Satisfactory follow-up colposcopy at 3 months Berget 1991 reports longer follow up for residual disease outcome: residual disease (histological) at 3, 9, 15, 21, 33, 45, 80 months
Notes	103 randomised to laser, 101 randomised to cryotherapy Laser performed ablated 2 mm lateral to transformation zone to a depth of 5-7mm Cryo coagulation (double freeze thaw freeze technique) or more if the ice ball did not exceed the probe (25mm) by 4 mm. Local analgesia was not routinely administered 6 laser and 2 cryotherapy women refused to be followed up Women were offered repeat treatment with the same method of treatment as part of protocol. 3 laser and 6 cryotherapy women refused repeat treatment
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Not reported, “patients fulfilling the criteria were randomized to either laser or cryo treatment”
Allocation concealment?	Unclear	Not reported
Blinding? All outcomes	Unclear	Not reported
Incomplete outcome data addressed? All outcomes	Yes	For residual disease: % analysed: 187/204 (92%) Laser; 94/103 (91%) Cryotherapy; 93/101 (92%) All other outcomes had less loss to follow up
Free of selective reporting?	Unclear	Insufficient information to permit judgement
Free of other bias?	Unclear	Insufficient information to assess whether an important risk of bias exists