Trends in research on pain relief during oocyte retrieval for IVF/ICSI: a systematic, methodological review

STUDY QUESTION: What is the methodological validity and usefulness of randomized controlled trials (RCTs) on pain relief during oocyte retrieval for IVF and ICSI? SUMMARY ANSWER: Key methodological characteristics such as randomization, allocation concealment, primary outcome measure and sample size calculation were inadequately reported in 33-43% of the included RCTs, and a broad heterogeneity is revealed in the studied outcome measures. WHAT IS KNOWN ALREADY: A Cochrane review on conscious sedation and analgesia for women undergoing oocyte retrieval concluded that the overall quality of evidence was low or very low, mainly owing to poor reporting. This, and heterogeneity of studied outcome measures, limits generalizability and eligibility of results for meta-analysis. STUDY DESIGN, SIZE, DURATION: For this review, a systematic search for RCTs on pain relief during oocyte retrieval was performed on 20 July 2020 in CENTRAL CRSO, MEDLINE, Embase, PsycINFO, CINAHL, ClinicalTrials.gov, WHO ICTRP, Web of Science, Portal Regional da BVS and Open Grey. PARTICIPANTS/MATERIALS, SETTING, METHODS: RCTs with pain or patient satisfaction as an outcome were included and analysed on a set of methodological and clinical characteristics, to determine their validity and usefulness. MAIN RESULTS AND THE ROLE OF CHANCE: Screening of 2531 articles led to an inclusion of 51 RCTs. Randomization was described inadequately in 33% of the RCTs. A low-risk method of allocation concealment was reported in 55% of the RCTs. Forty-nine percent of the RCTs reported blinding of participants, 33% of blinding personnel and 43% of blinding the outcome assessor. In 63% of the RCTs, the primary outcome was stated, but a sample size calculation was described in only 57%. Data were analysed according to the intention-to-treat principle in 73%. Treatment groups were not treated identically other than the intervention of interest in 10% of the RCTs. The primary outcome was intraoperative pain in 28%, and postoperative pain in 2%. The visual analogue scale (VAS) was the most used pain scale, in 69% of the RCTs in which pain was measured. Overall, nine other scales were used. Patient satisfaction was measured in 49% of the RCTs, for which 12 different methods were used. Occurrence of side-effects and complications were assessed in 77% and 49% of the RCTs: a definition for these was lacking in 13% and 20% of the RCTs, respectively. Pregnancy rate was reported in 55% of the RCTs and, of these, 75% did not adequately define pregnancy. To improve the quality of future research, we provide recommendations for the design of future trials. These include use of the VAS for pain measurement, use of validated questionnaires for measurement of patient satisfaction and the minimal clinically relevant difference to use for sample size calculations. LIMITATIONS, REASONS FOR CAUTION: Consensus has not been reached on some methodological characteristics, for which we formulated recommendations. To prevent further heterogeneity in research on this topic, recommendations were formulated based on expert opinion, or on the most used method thus far. Future research may provide evidence to base new recommendations on. WIDER IMPLICATIONS OF THE FINDINGS: Use of the recommendations given for design of trials on this topic can increase the generalizability of future research, increasing eligibility for meta-analyses and preventing wastefulness.