How accurate is diagnosis of asthma in a general practice database? A review of patients' notes and...

Planned care of patients with chronic diseases in primary care depends on being able to identify them. A recorded label of asthma does not necessarily mean that the patient is currently symptomatic, and failure to record the diagnosis may influence future care.

To determine the degree of under- and over-reporting of the diagnosis of asthma for patients aged 16-55 years inclusive in one large general practice.

A questionnaire validated for the detection of bronchial hyper-reactivity was sent to all patients recorded as having asthma and their matched controls. Patients with a diagnosis of asthma and symptomatic bronchial hyper-reactivity were considered to have asthma. Evidence of asthma in the written and computer records was sought for two groups: patients with asthma and without symptoms of bronchial hyper-reactivity, and controls with symptoms of bronchial hyper-reactivity.

A semi-rural group practice with 14 830 patients.

Questionnaires were sent to 833 patients and 831 controls matched by age and sex.

Response rates were 79.1% (659/833)for patients with asthma and 70.6% (587/831) for control patients. Of the patients with asthma who replied, 60.5% (399/659) had symptomatic bronchial hyper-reactivity. Of those with asthma and a negative bronchial hyper-reactivity status (based on the questionnaire), 190/260 (73.1%) were considered to have had asthma when diagnosed, on review of their primary care records. There was no evidence to suggest asthma in 45 (17.3%) of the 260 patients who had a negative bronchial hyper-reactivity status. Of the control patients, 41 (7.0%) of the 587 responders had symptomatic bronchial hyper-reactivity and nine of these may have asthma. By extrapolation, we estimate that there were possibly another 99 patients with symptoms of asthma, who had not been labelled as having asthma, and 362 patients with symptoms of bronchial hyper-reactivity who had not reported them to their doctors or had not had them recognised.

There is an 89.4% chance that a patient recorded as having asthma has, or has had, asthma.