Quality indicators are ubiquitous in healthcare and serve a variety of purposes for many different stakeholders. Few would question the value of monitoring the quality of care, but the increasing numbers of indicators and the resources consumed suggest that some reflection and refinement of approach may be required. For instance, the National Quality Forum catalogue in the USA lists 1167 indicators,1 and a recent study from the Netherlands showed that healthcare professionals from five clinical specialties collect data for 24 different stakeholders on 1380 different variables.2 Healthcare professionals in the latter study spent an average of 52 min per working day documenting for the wide range of required quality registrations, with only 36% of the indicators perceived as useful for improving the quality of care in daily practice.2

In this issue of BMJ Quality & Safety, Xu and colleagues report a study of the usefulness of nursing home indicators for assuring and improving quality of care.3 These indicators play a role in value-imbursement initiatives, and facility scores are publicly reported on Minnesota’s Nursing Home Report Card. This study is notable for focusing on the overall value of the set of indicators rather than the properties of individual indicators. The authors performed a qualitative assessment of the indicator set using literature review and expert opinion. They also examined correlations between indicators and examined the contribution of each indicator to the assessment of overall nursing home quality. They refined the indicator list, provided a clear domain structure and scoring system, making it much easier for users to understand what is being measured and how the summative assessment can be used to support decision-making. Their approach is analogous to that taken by the development of psychological tests, where the emphasis lies on carefully defining the underlying construct and developing a necessary and sufficient set of indicators to measure that construct.

While individual quality indicators have been extensively studied, and much written about the criteria for a good indicator, considerably less attention has been devoted to the criteria and desirable characteristics of sets of indicators. The paper by Xu and colleagues shows that there is much to be gained by shifting the level of analysis to reflect on the underlying constructs and wider purpose of indicator sets. Rather than accumulating and aggregating multiple individual indicators, in the hope that they will meet the needs of users and health systems, we could endeavour to define the fundamental purpose of indicator sets and then choose relevant component indicators. In this editorial, we attempt to define a core set of questions that could help to shape and refine the core features of an indicator set.