Association between home insulation and hospital admission rates: retrospective cohort study using linked data from a national intervention programme.

Objectives: To investigate whether retrofitting insulation into homes can reduce cold associated hospital admission rates among residents and to identify whether the effect varies between different groups within the population and by type of insulation.

Design: A quasi-experimental retrospective cohort study using linked datasets to evaluate a national intervention programme.

Participants: 994 317 residents of 204 405 houses who received an insulation subsidy through the Energy Efficiency and Conservation Authority Warm-up New Zealand: Heat Smart retrofit programme between July 2009 and June 2014.