Determinants of inter-practice variation in childhood asthma and respiratory infections: cross-sectional study of a national sentinel network.

Objectives Respiratory infections are associated with acute exacerbations of asthma and accompanying morbidity and mortality. In this study we explore interpractice variations in respiratory infections in children with asthma and study the effect of practice-level factors on these variations. Design Cross-sectional study. Setting We analysed data from 164 general practices in the Royal College of General PractitionersResearch and Surveillance Centresentinel network in England. Participants Children 5-12 years. Interventions None. In this observational study, we used regression analysis to explore the impact of practice-level determinants on the number of respiratory infections in children with asthma. Primary and secondary outcome measures We describe the distribution of childhood asthma and the determinants of upper/lower respiratory tract infections in these children. Results 83.5% (137/164) practices were in urban locations; the mean number of general practitioners per practice was 7; and the mean duration since qualification 19.7 years. We found almost 10-fold difference in the rate of asthma (1.5-11.8 per 100 children) and 50-fold variation in respiratory infection rates between practices. Larger practices with larger lists of asthmatic children had greater rates of respiratory infections among these children. Conclusion We showed that structural/environmental variables are consistent predictors of a range of respiratory infections among children with asthma. However, contradictory results between measures of practice clinical care show that a purely structural explanation for variability in respiratory infections is limited. Further research is needed to understand how the practice factors influence individual risk behaviours relevant to respiratory infections.