Influencing Clinical Outcomes
The integral importance of laboratory tests to the day-to-day practice of medicine is widely accepted. Although the assertion that test results influence approximately 70% of clinical decisions has recently been questioned, it is clear that a comprehensive LM service is essential to deliver high quality evidence-based care. The difference that such laboratory tests make to clinical outcomes is beyond dispute but quantifying the effect of testing remains a challenging task. Although the importance of laboratory-related outcomes is now well recognised, difficulties in designing rigorous studies of the effects of laboratory tests on clinical outcomes has resulted in a limited evidence-base in contrast to the plethora of randomised controlled trials underpinning therapeutic interventions. Even more challenging is the need to measure the added value of the contributions made by laboratory-based physicians (Box 1). As we increasingly move towards patient-centred healthcare systems, it could be argued that the only justification for laboratory-based physicians would be to ensure that they make a clear difference to patient outcomes. In this regard, three levels of laboratory-related patient outcomes have been defined (Box 2).
Clinical quality indicators for LM have recently been defined using focus group consultation and subsequent ranking by an expert panel of primary and secondary care physicians. The top 10 indicators defined by this approach included the communication of critical results, education of users and quality assurance but crucially did not include the quality of interpretative comments which is the focus of this paper.
Given the difficulties in precisely measuring the contribution of laboratory-based physicians to clinical outcomes, this paper highlights the vital contribution made to patient care by expert interpretation of laboratory tests as exemplified in the following case histories.