Potential and pitfalls of personal reference intervals in general practice: A focus group and case vignette study...

Personalised medicine is increasingly used in clinical practice and tailors care to individual characteristics. A new application in laboratory diagnostics is personalised reference intervals (PeRIs). Unlike population-based reference intervals (PoRIs), PeRIs use previous results of the patient, providing ranges tailored to an individual's own baseline. This may improve interpretation of laboratory results and possibly patient care.

This study aims to explore perspectives of general practitioners (GPs) on PeRIs, and maps the identified benefits, disadvantages, risks and prerequisites before implementation of PeRIs.

Focus groups (n = 3; 16 GPs) and a vignette study with fictional cases (n = 98) were used to explore the opinion, interpretation and application of PeRIs among Dutch GPs.

Focus groups and the survey identified benefits, including easier interpretation, efficiency and more meaningful follow-up and referrals, as well as risks such as alert fatigue, overreliance, and underdiagnosis. The survey showed that PeRIs may alter GP behaviour. When a haemoglobin result was presented with versus without a PeRI comment, a significant portion of GPs adjusted their clinical strategy in these fictional cases. Participants emphasised that PeRIs should support, not replace clinical judgement.

Our study reveals arguments both supporting and opposing PeRIs. Importantly, GPs perceived added value for diagnostic decision-making. We advise accompanying implementation of PeRI with education on responsibilities and underlying algorithms. In this way, PeRIs can contribute to behavioural change that may lead to better and more meaningful, personalised care.