Methods	RCT
Participants	375 women with cervical smears suggesting CIN 2 or 3, or 2 smears equivalent to CIN1 Women with adequate colposcopy included with entire lesion visible, not pregnant Women with vaginitis, lesion extending to vagina, evidence of invasion excluded
Interventions	Primary LLETZ Colposcopic directed biopsy and endocervical curettage, Only if positive laser ablation of transformation zone
Outcomes	Histological status of LLETZ or colposcopic specimens Operators impression of significant peri-operative bleeding Women’s subjective opinion of peri-operative pain Women’s subjective opinion of post-operative severe discomfort, heavy discharge, severe bleeding Residual disease (cytology) at 3 and 6 months
Notes	195 randomised to LLETZ, 180 to Laser All women had paracervical 1% lidocaine with 1:100,000 ephedrine LLETZ group: 6 treated by laser ablation due to technical problems, 4 failed to attend for treatment Laser group: 66 women did not require treatment, 114 required treatment 4 women were treated by LLETZ, 2 by cryosurgery due to technical problems
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	Computer generation was used to assign women to either LLETZ or laser, “they (patients) were assigned a treatment strategy by computer-randomised forms”
Allocation concealment?	Yes	“Computer-randomised forms contained in sealed opaque envelopes”, were used as a method of concealment
Blinding? All outcomes	Unclear	Not reported
Incomplete outcome data addressed? All outcomes	No	% analysed: 190/375 (51%) and 107/375 (29%) for residual disease at 3 and 6 months respectively, “of the 190 who were compliant with follow up 3 months after treatment … 107 returned for a second evaluation at 6 months” All other outcomes assessed more than 51% of women.
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