The problem with uptake as a quality metric for population-based screening programmes

Quality measurement that focuses on important processes and outcomes within healthcare is typically seen as an essential feature of well-functioning healthcare systems.1 While outcome measures are concerned with assessing the impact of healthcare interventions (eg, the number of adverse drug events or the average length of stay for inpatients), process measures focus instead on assessing whether elements or steps within healthcare systems are happening as planned (eg, the number of patients seen in a clinic or the proportion of patients receiving a particular intervention). The relationship between processes and outcomes is acknowledged to be complex. Many population-based screening programmes, both in the UK and internationally, have as a key performance indicator (KPI) some sort of measure that assesses how many of the population eligible for that screening intervention participate in it (typically referred to as either ‘uptake’ or ‘coverage’). For example, for the adult (non-pregnancy) screening programmes offered by the NHS in the UK, all five programmes include a KPI of this kind, with acceptable (ie, minimum) thresholds made explicit. But is this simple process measure of the uptake of screening programmes a good assessment of healthcare quality? In this viewpoint paper, we highlight some of the shortcomings in using uptake to measure quality in this context and offer some possible ways forward.