Nick Summerton

The medical history as a diagnostic technology

The medical history is a powerful diagnostic technology. However, in seeking to establish an appropriate balance between the history and the other diagnostic modalities more explicit consideration must be given to the performance characteristics of the medical history. Building on recent work undertaken in the UK and elsewhere in Europe it is now feasible to develop a library of setting-specific likelihood ratios and kappa statistics for key elements of the medical history. Of particular importance to those working in primary care, statistically adjusted combinations of information from the medical history can be generated; furnishing clinicians with likelihood ratios of significant magnitudes. It is suggested that developing a more rational approach to the use of the medical history could lead to improvements in diagnostic efficiency and effectiveness, with benefits for individual patient care in addition to the overall NHS budget. When diagnosis is viewed as a processing pathway founded on a robust medical history, it becomes clear than in some situations investigations may become unnecessary and, in other circumstances, their impact will be enhanced.

A survey of statistics in three UK general practice journal

BackgroundMany medical specialities have reviewed the statistical content of their journals. To our knowledge this has not been done in general practice. Given the main role of a general practitioner as a diagnostician we thought it would be of interest to see whether the statistical methods reported reflect the diagnostic process.MethodsHand search of three UK journals of general practice namely the British Medical Journal (general practice section), British Journal of General Practice and Family Practice over a one-year period (1 January to 31 December 2000).ResultsA wide variety of statistical techniques were used. The most common methods included t-tests and Chi-squared tests. There were few articles reporting likelihood ratios and other useful diagnostic methods. There was evidence that the journals with the more thorough statistical review process reported a more complex and wider variety of statistical techniques.ConclusionsThe BMJ had a wider range and greater diversity of statistical methods than the other two journals. However, in all three journals there was a dearth of papers reflecting the diagnostic process. Across all three journals there were relatively few papers describing randomised controlled trials thus recognising the difficulty of implementing this design in general practice.

Diagnostic triage and the role of natriuretic peptide testing and echocardiography for suspected heart failure: an appropriateness ratings evaluation by UK GPs

BACKGROUND Some UK GPs are acquiring access to natriuretic peptide (NP) testing or echocardiography as diagnostic tests for heart failure. This study developed appropriateness ratings for the diagnostic application of these tests in routine general practice. AIM To develop appropriateness ratings for the diagnostic application of NP testing or echocardiography for heart failure in general practice. DESIGN AND SETTING An appropriateness ratings evaluation in UK general practice. METHOD Four presenting symptoms (cough, bilateral ankle swelling, dyspnoea, fatigue), three levels of risk of cardiovascular disease (low, intermediate, high), and dichotomous categorisations of cardiovascular/chest examination and electrocardiogram result, were used to create 540 appropriateness scenarios for patients in whom NP testing or echocardiography might be considered. These were rated by a 10-person expert panel, consisting of GPs and GPs with specialist interests in cardiology, in a two-round RAND Appropriateness Method. RESULTS Onward referral for NP testing or echocardiography was rated as an appropriate next step in 217 (40.2%) of the 540 scenarios; in 194 (35.9%) it was rated inappropriate. The ratings also show where NP testing or echocardiography were ranked as equivalent next steps and when one test was seen as the more appropriate than the other. CONCLUSION NP testing should be the routine test for suspected heart failure where referral for diagnostic testing is considered appropriate. An abnormal electrocardiogram status makes referral to echocardiography an accompanying, or more appropriate, next step alongside NP testing, especially in the presence of dyspnoea. Abnormal NP testing should subsequently be followed up with referral for echocardiography.