Retrofitting home insulation reduces incidence and severity of chronic respiratory disease

To assess whether retrofitting home insulation can reduce the risk of respiratory disease incidence and exacerbation, a retrospective cohort study was undertaken using linked data from a national intervention program. The study population was made up of 1 004 795 residents from 205 001 New Zealand houses that received an insulation subsidy though a national Energy Efficiency and Conservation Authority program. A difference‐in‐difference model compared changes in the number of prescriptions dispensed for respiratory illness post‐ insulation to a control population over the same timeframe. New prescribing of chronic respiratory disease medication at follow‐up was used to compare incidence risk ratios between intervention and control groups. Chronic respiratory disease incidence was significantly lower in the intervention group at follow‐up: odds ratio 0.90 (95% CI: 0.86–0.94). There was also a 4% reduction in medication dispensed for treating exacerbations of chronic respiratory disease symptoms in the intervention group compared with the control group: relative rate ratio (RRR) 0.96 (95% CI: 0.96–0.97). There was no change in medication dispensed to prevent symptoms of chronic respiratory disease RRR: 1,00 (95% CI: 0.99–1.00). These findings support home insulation interventions as a means of improving respiratory health outcomes.