A model of the relationship between consultation behaviour for asthma in a general practice and the weather

The aim of this study was to build a model showing the relationship between consultations for asthma and the daily weather in a suburban computerised general practice in New Zealand. A retrospective count of the number of asthmatic patients attending the practice on any particular day for a consultation for asthma was compared with the weather variables temperature, rainfall, relative humidity, and wind strength. Quasi-likelihood Poisson regression models were built in steps. There were 3844 consultations for asthma between October 1, 1986 and October 30, 1991. The number varied from 0 to 11 consultations per day (mean 2.1). The annual means were 1.3, 1.9, 2.3, 2.5, and 2.7 consultations per day, respectively. After variables indicating time trends, days of the week, and holiday periods were included in the model, temperature and relative humidity provided the only significant additional explanatory power for variation in consultations.