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Table 1 The PRE-EMPT trial protocol summary

From: Women’s experiences of medical treatment for endometriosis and its impact on PRE-EMPT trial participation: a qualitative study

Design A randomised, pragmatic multicentre trial with integrated economic evaluation
Setting Up to 40 NHS hospitals within the UK
Target population Women of reproductive age, who are undergoing laparoscopy to investigate whether their pelvic pain is due to endometriosis
Exclusion criteria Current infertility, immediate plans to conceive
Health technologies assessed The main comparison is long-acting reversible contraception (LARC) versus combined oral contraceptive pill (COCP). Participants can have a pre-randomisation choice of LARC (or alternatively one will be randomly allocated):
i) Levonorgestrel-releasing intra-uterine system (LNG-IUS) (fitted by a gynaecologist) or
ii) 3 monthly depot medroxyprogesterone acetate (DMPA) injections (administered by the patient’s gynaecologist or general practitioner); subcomparisons will be stratified by this choice
Outcomes The primary outcome is the recurrence of symptoms as evaluated by the pain domain of the Endometriosis Health Profile–30 (EHP-30) questionnaire at 36 months post-randomisation. The EHP-30 is a validated, responsive health-related quality of life measure for endometriosis. It will also be assessed prior to randomisation and at 6, 12 and 24 months.
Secondary outcomes:
• All other symptom and quality of life (QoL) domains of the EHP-30
• Non-menstrual pelvic pain and dysmenorrhea measured by 0–100 visual analogue (VAS) pain scale
• Fatigue, as measured by the Fatigue Severity Score
• Menstrual regularity
• Generic QoL (EQ-5D) and capabilities, as measure of wellbeing (ICE-CAP)
• Further diagnostic and therapeutic surgery for endometriosis (as a proxy for recurrence)
• Discontinuation rates of randomised treatment, with reasons for change, serious adverse events
• Cost per quality-adjusted life year (QALY) and cost per change in symptom score.
• An increased knowledge of issues identified as important by the participants regarding their treatment and its impact on their lives
Analysis The main comparison will be LARC vs COCP, with sub-comparisons of the groups where the intention is to treat with either LNG-IUS or DMPA if randomised to LARC. The primary outcome will be analysed using a linear regression model including a variable for each treatment group and including baseline score and the minimisation factors as covariates. Effect sizes will be presented as point estimates and 95% confidence intervals. Standard statistical methods will be used for other outcomes. All analysis will be by intention to treat.
Sample The study will have 90% power (p = 0.05) to detect an 8-point difference in the main comparison assuming the standard deviation of the EHP-30 pain domain is 22 points. This will require 160 women per group, 320 in total. To account for 20% loss to follow-up, this target has been inflated to 400 women in total