Test of timeBMJ 2009; 338 doi: https://doi.org/10.1136/bmj.b1878 (Published 15 June 2009) Cite this as: BMJ 2009;338:b1878
- Susanna C Almond, academic clinical fellow in general practice,
- Nick Summerton, clinical consultant
- 1Department of Primary Health Care, University of Oxford, Oxford OX3 7LF
- Correspondence to: S C Almond
What is it?
Patients often present to general practitioners with symptoms or signs that are ill defined and evolving, making it difficult to slot them neatly into a diagnostic category. In a cohort study of 500 patients presenting with common symptoms, 70% had improved at two weeks’ follow-up, and 60% of the remainder had improved at three months.1 Making a precise diagnosis of all presenting problems is arguably not only unnecessary but also potentially damaging both to the patient and to the overall healthcare budget.2
General practice presents a good opportunity for using the test of time for diagnosis since arranging reassessment is relatively easy. Gray says that the general practice consultation should be seen as a total of 47 minutes spread over the course of a year, rather than a discrete 10 minute entity, allowing repeated evaluation in situations of diagnostic uncertainty.3
Diagnosis by test of time involves a careful initial assessment of the patient’s presenting problem(s), followed by one or more reassessment(s) after predefined period(s) of time. At the reassessment(s) the symptom or sign might have become more clearly defined, might have resolved, might be unchanged, or might have worsened, or additional signs or symptoms may have appeared. Diagnosis by time therefore relies on a good understanding of the course of condition(s) to enable appropriate reassessment(s). This article considers the test of time as a diagnostic method that is often used for defining the final diagnosis (figure)⇓.4
When can it be used?
In applying this diagnostic strategy it is important to distinguish those patients who require …