Association between respiratory prescribing, air pollution and deprivation, in primary health care

We investigated the association between respiratory prescribing, air quality and deprivation in primary health care. Most previous studies have used data from secondary and tertiary care to quantify air pollution effects on exacerbations of asthma and chronic obstructive pulmonary disease (COPD). However, these outcomes capture patients who suffer from relatively severe symptoms. This is a population-based ecological study. We analysed respiratory medication (salbutamol) prescribed monthly by 63 primary care practices, UK. Firstly, we captured the area-wide seasonal variation in prescribing. Then, using the area-wide variation in prescribing as an offset, we built a mixed-effects model to assess the remaining variation in relation to air quality and demographic variables. An increase of 10 g/m(3) in ambient PM10 was associated with an increase of 1 (95 CI: 0.12) in salbutamol prescribing. An increase of 1 SD in income and employment deprivation was associated with an increase of 20.5 (95 CI: 8.833.4) and 14.7 (95 CI: 4.326.2) in salbutamol prescribing rate, respectively. The study provides evidence that monthly respiratory prescribing in primary care is a useful indicator of the extent to which air pollution exacerbates asthma and COPD symptoms. Respiratory prescribing was higher on deprived populations.