Core outcome sets will improve the quality of obstetrics research

Abstract

Anyone who has ever tried to make sense of the medical literature as a systematic reviewer, a clinical trialist, a clinician, or a patient will likely recognise the problem so elegantly demonstrated by Meher and Alfirevic. They have shown that variability in both what to measure, for example length of gestation or perinatal morbidity, and how to measure, for example defining necrotising enterocolitis, leads to difficulty in summarising the evidence for interventions for preterm birth prevention. The effect is to limit the contribution to advancing the usefulness of research in informing clinical practice and empowering patients with information to make decisions about interventions. As the authors suggest, a solution to this problem is the development of a core outcome set. This is a minimum set of agreed standardised outcomes that would be measured and reported in all trials in a specific condition. It then follows that this same set would be relevant for the systematic reviews of those trials. The advantage in terms of combining and contrasting results from different studies if they all measured key outcomes is obvious. The most established core outcome set, developed for rheumatoid arthritis, is now measured and reported in nearly three-quarters of studies (Kirkham et al. Trials 2013;14:324). Resources to support core outcome set development are being brought together in the Core Outcome Measures in Effectiveness Trials (COMET) initiative (www.cometinitiative.org). COMET provides a publically available searchable database of published and continuing core outcome set work, soon to be supplemented by the results from a systematic review of over 25 000 papers. This is a unique resource, which will be updated periodically, and should serve to minimise unnecessary duplication. Various methods have been used to develop core outcome sets, but there is limited empirical evidence regarding whether different methods lead to similar or different conclusions. Key issues to consider have been proposed (Williamson et al. Trials 2012;13:132), and include: (1) defining the scope of the healthcare area that the set will apply to, in terms of health condition, population, and types of interventions; (2) identifying existing knowledge, including reviews of previous trials, such as that undertaken by Meher and Alfirevic; (3) choice of method for determining consensus; and (4) determining who the key groups are to involve. As Meher and Alfirevic note, it is ‘important that RCTs and systematic reviews measure end points that are relevant and meaningful to patients, clinicians, and health service providers'. Although the original core outcome set for rheumatoid arthritis was developed by clinicians alone, patients have subsequently been asked which outcomes are most important to them. They identified fatigue, an outcome not previously included in the set. COMET aims to foster methodological research into core outcome set development, including how best to engage patients in this work, and to encourage the publication of study protocols (e.g. Harman et al. Trials 2013;14:70). In conclusion, the adoption of core outcome sets has the potential to increase the consistency in outcomes measured across trials, and to ensure that trials are more likely to measure appropriate outcomes. Paula Williamson chairs the Management Group of the COMET initiative.