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Abstract
Objectives We carried out an evaluation of a large-scale New Zealand retrofit programme using administrative data that provided the statistical power to assess the effect of insulation and/or heating retrofits on cardiovascular and respiratory-related mortality in people aged 65 and over with prior respiratory or circulatory hospitalisations.
Design Quasi-experimental cohort study based on administrative data.
Setting New Zealand.
Participants From a larger study cohort of over 900 000 people, we selected two subcohorts: 3287 people who were aged 65 and over and had experienced pretreatment period cardiovascular-related hospitalisation (ICD-10 chapter 9), and 1561 people aged 65 and over who had experienced pretreatment respiratory-related hospitalisation (ICD-10 chapter 10).
Interventions Treatment group individuals lived in a home that received insulation and/or heating retrofits under the Warm Up New Zealand: Heat Smart programme. Control group individuals lived in a home that was matched to a treatment home based on physical characteristics and location.
Primary and secondary outcome measures HR for all-cause mortality for treatment with insulation, heating, or insulation and heating relative to control group.
Results People with pretreatment circulatory hospitalisation who occupied a household that received only insulation had an HR for all-cause mortality of 0.673 (95% CI 0.535 to 0.847) (p<0.001) relative to control group members. Individuals with a pretreatment respiratory hospitalisation who occupied a household that received only an insulation retrofit had an HR for all-cause mortality of 0.830 (95% CI 0.655 to 1.051) (p=0.122) relative to control group members. There was no evidence of an additional benefit from receiving heating.
Conclusions We interpret the hazard rate observed for cardiovascular subcohort individuals who received insulation as evidence of a protective effect, reducing the risk of mortality for vulnerable older adults. There is suggestive evidence of a protective effect of insulation for the respiratory subcohort.
- public health
- health economics
- epidemiology
- housing
- insulation
- evaluation
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Footnotes
Contributors NP: wrote the PhD thesis the article is based on; carried out statistical analyses presented. MK: supervised PhD thesis; contributed statistical advice on analyses presented and reviewed and contributed to structure and presentation of statistical content of this paper; aided in drafting and revision of paper. LT-B: designed the Warm Up New Zealand: Heat Smart study protocol; led the analysis of health data from that study; carried out initial analysis of mortality presented in the 2011 report; contributed to literature review and paper generally; aided in drafting and revision of paper. AG: supervised thesis; led cost benefit-based evaluation that this study contributed to; contributed to design of Warm Up New Zealand: Heat Smart study protocol; contributed advice on statistical analyses presented; contributed to structure of paper, discussion section and terminology; aided in drafting and revision of paper. PH-C: supervised thesis; contributed to design of Warm Up New Zealand: Heat Smart study protocol; contributed to discussion, literature review and wording; aided in drafting and revision of paper.
Funding This article was derived from a PhD thesis based on a comprehensive policy evaluation that was funded by New Zealand’s Ministry of Economic Development in 2009.
Competing interests None declared.
Ethics approval Research approved by New Zealand Multiregion Ethics Committee on 2 March 2010, ethics ref MEC/10/EXP/002.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data available.