Background. There is a need in primary care for simple asthma outcome measu
res that are valid in terms of their relationship with lung function and ca
pable of predicting those patients for whom additional management is indica
ted.
Aim. To assess the predictive validity of a revised asthma morbidity index
in United Kingdom (UK) general practice.
Method. Morbidity index and peak flow rate data were gathered from nine gen
eral practices over a three-month period. Two postal questionnaire surveys,
one year apart, were conducted in one Tyneside general practice. Morbidity
index data from 570 asthmatic patients were gathered in the first survey a
nd used to predict morbidity over the next year.
Results. For 120 responders with low morbidity, mean peak flow as a percent
age of the predicted Value was 91% (SD = 21%); for 91 responders with mediu
m morbidity, the per centage was 77% (SD = 21%); and for 90 responders with
high morbidity, it was 63% (SD = 29%). Fifty-seven per cent of the morbidi
ty index categories remained unchanged after 72 months. The relative risks
of high morbidity for having any acute asthma attacks, more than four attac
ks, and needing oral steroids during a one year period were 2.88 (CI = 1.87
to 4.43), 2.52 (Cl = 1.84 to 3.44) and 2.38 (Cl = 1.70 to 3.33) respective
ly.
Conclusion. The revised morbidity index is a simple and valid tool for the
opportunistic surveillance of asthma in primary care.