Impact of a Heating Voucher on Health Outcomes in COPD Patients: A Randomised Controlled Trial

Aotearoa New Zealand (NZ) homes are cold by international standards, with many failing to achieve temperatures recommended by WHO housing and health guidelines. Despite strong evidence of seasonal exacerbations in Chronic Obstructive Pulmonary Disease (COPD), there has been little examination of the effect of household warmth, or housing quality on COPD outcomes. The Warm Homes for Elder New Zealanders (WHEZ) study aimed to see if subsidising electricity costs would improve the health outcomes of older people with COPD. Previous analysis showed a modest, typically 2-10% dependent on prior usage, increase in electricity use among the subsidised households.

Participants aged over 55 with doctor-diagnosed COPD were recruited from three regional centres, and where possible their dwelling was insulated after enrolment. A single-blinded randomised controlled trial of the effect of an electricity voucher (NZ$500) on health care usage during winter was carried out in three locations across New Zealand. The primary outcome was exacerbations treated with antibiotics, and/or corticosteroids. The Clinical Trial Registration is NCT01627418. Of the 520 participants assigned to a wave, partial or better data was achieved for 424; 215 of those were randomised to the early intervention group, and 209 to receive the intervention later.

Despite the modest increase in energy use by study households, reported previously, there was no significant difference between study arms in the frequency of exacerbation of COPD (0.089, p=0.5875, 95% CI -1.406-1.584) nor hospitalisations. An exploratory analysis suggested a lower mortality among participants assigned to receive the intervention first (OR 0.310, p=0.0175, 95% CI 0.118-0.815).

This study showed little effect of winter electricity vouchers on exacerbations of COPD. However, such vouchers increased energy use and may have reduced overall mortality. A larger study, particularly with susceptible subpopulations, is recommended to examine this mortality impact further.