Accuracy of perception of severity of asthma: patients treated in general practice.

To determine the frequency of poor perception of severity of asthma in general practice. Asthmatic patients recorded their perceived severity of asthma, with a visual analogue score, and a coded measurement of their peak expiratory flow up to four times daily for 14 consecutive days. 11 general practices in and around Bristol. 255 asthmatic patients (139 men and 116 women) aged 17-76 who were recruited by random selection from the general practices' disease registers or when they requested prescriptions for inhaled bronchodilators. Correlation between visual analogue scores and peak expiratory flow (as a percentage of predicted peak flow). 152 (60%) of the patients showed no significant correlation between visual analogue asthma scores and simultaneous peak flow measurements (p > 0.05) and were termed poor discriminators. The distribution of good and poor discriminators within each general practice was similar (chi 2 = 6.11, df = 10). The two groups were not characterised by differences in the maximum, minimum, or standard deviation of peak expiratory flow or visual analogue score; in age; or in the proportion of men and women in each group. In general practice a high proportion of asthmatic patients do not reliably detect changes in their lung function. This reinforces the need for careful objective assessment of lung function in the management of asthma.