Polymyalgia rheumatica in primary care: a cohort study of the diagnostic criteria and outcome.

BACKGROUND

Polymyalgia rheumatica (PMR) is common and is usually diagnosed and managed in primary care. There are no generally accepted primary care criteria for diagnosis.

OBJECTIVES

To identify what features are used to diagnose PMR, to benchmark these against diagnostic criteria and to identify features at diagnosis with prognostic significance.

METHODS

This was a retrospective cohort study of all patients diagnosed with PMR in three UK general practices between January 1994 and December 2003. The medical records were examined for features of PMR. The duration of steroid treatment was used as a proxy for duration of disease. Analysis of prognostic predictors was by Cox proportional hazards models.

RESULTS

One hundred and eighty-three patients were identified, giving an overall annual incidence of 11.3 per 10 000 patients aged 50 or over. The median age at diagnosis was 75 (interquartile range 69, 79) years: 138 (75%) were female. The most common diagnostic features were proximal muscle pain in 151 (82%), raised inflammatory markers in 160 (87%), clinical response to corticosteroids in 166 (91%) and normalization of inflammatory markers in 147 (81%). Twenty (11%) had normal inflammatory indices. The median duration of treatment was 1.4 years (interquartile range 0.8, 2.4). Female sex and raised inflammatory markers were independently associated with longer treatment: female hazard ratio 1.5 (1.0, 2.2) P = 0.047 and raised inflammatory markers 2.0 (1.2, 3.2) P = 0.01.

CONCLUSIONS

Primary care practitioners do not use established criteria to diagnose PMR and sometimes diagnose the condition even when inflammatory markers are normal. This exposes patients to a risk of inappropriate steroid use.