Seasonal variation and time trends in childhood asthma in England and Wales 1975-81.

In England and Wales hospital admissions for childhood asthma almost trebled over the period 1975-81. This may have reflected a true increase in the incidence of acute asthma, a swing from primary to hospital care, or both. The trend was not due to a change in diagnostic fashion. Monthly admissions showed a pronounced seasonal variation with fewest admissions in winter, rising in spring and early summer to peak in the autumn. A deep admission trough was present in August. The monthly admission profile was very similar throughout England and Wales, suggesting that major "trigger" factors were responsible.