Efficiency over thoroughness in laboratory testing decision making in primary care: findings from a realist review

Existing research demonstrates significant variation in test-ordering practice, and growth in the use of laboratory tests in primary care. Reviews of interventions designed to change test-ordering practice report heterogeneity in design and effectiveness. Improving understanding of clinicians' decision making in relation to laboratory testing is an important means of understanding practice patterns and developing theory-informed interventions.

To develop explanations for the underlying causes of patterns of variation and increasing use of laboratory tests in primary care, and make recommendations for future research and intervention design.

Realist review of secondary data from primary care.

Diverse evidence, including data from qualitative and quantitative studies, was gathered via systematic and iterative searching processes. Data were synthesised according to realist principles to develop explanations accounting for clinicians' decision making in relation to laboratory tests.

A total of 145 documents contributed data to the synthesis. Laboratory test ordering can fulfil many roles in primary care. Decisions about tests are incorporated into practice heuristics and tests are deployed as a tool to manage patient interactions. Ordering tests may be easier than not ordering tests in existing systems. Alongside high workloads and limited time to devote to decision making, there is a common perception that laboratory tests are relatively inconsequential interventions. Clinicians prioritise efficiency over thoroughness in decision making about laboratory tests.

Interventions to change test-ordering practice can be understood as aiming to preserve efficiency or encourage thoroughness in decision making. Intervention designs and evaluations should consider how testing decisions are made in real-world clinical practice.