The short-term effect of particulate matter on cardiorespiratory drug prescription, as a proxy of mild adverse events.

Introduction And Aims: The association between particulate matter < 10µm in aerodynamic diameter (PM) and mild disease episodes, not leading to hospitalization or death, has been rarely investigated. We studied the short-term effect of PM on purchases of specific cardiorespiratory medications, as proxies of mild episodes, in 7 small- and medium-sized cities of Northern Italy, during 2005-2006.

Materials And Methods: We extracted information on purchased prescriptions from healthcare administrative databases, and we obtained daily PM concentrations from fixed monitoring stations. We applied a time-stratified case-crossover design, using the time-series of antidiabetic drugs purchases to control for confounding due to irregularities in daily purchase frequencies.

Results: During the warm season, we estimated a delayed (lags 2-6) increased risk of buying glucocorticoid (4.53%, 95% Confidence Interval (CI): 2.62, 6.48) and adrenergic inhalants (1.66%, 95% CI: 0.10, 3.24), following an increment (10μg/m) in PM concentration. During the cold season, we observed an immediate (lags 0-1) increased risk of purchasing antiarrhythmics (0.76%; 95% CI: 0.16, 1.36) and vasodilators (0.72%; 95% CI: 0.30, 1.13), followed by a risk reduction (lags 2-6), probably due to harvesting.

Conclusions: Focusing on drug purchases, we reached sufficient statistical power to study PM effect outside large urban areas and conclude that short-term increments in PM concentrations might cause mild cardiorespiratory disease episodes.