Using general practice data for chronic disease prevalence: the impact of record linkage on estimation accuracy

Diagnostic information in general practice records is often dispersed across practices, affecting population planning and research. Linking patient records across practices enhances diagnostic visibility and reveals a more complete picture of chronic disease burden, highlighting the risk of overestimating disease prevalence when analyses are restricted to active patient records alone. This overestimation likely results from excluding healthier patients with fewer healthcare encounters. Small differences in prevalence estimates can have substantial implications on population-level planning, potentially affecting funding allocations, clinical guideline, and workforce decisions. These findings suggest the need for linked general practice datasets to improve the accuracy of prevalence estimates and inform effective policy and resource allocation decisions in primary care.