Home modification to reduce falls at a health district level: Modeling health gain, health inequalities and health costs

BACKGROUND: There is some evidence that home safety assessment and modification (HSAM) is effective in reducing falls in older people. But there are various knowledge gaps, including around cost-effectiveness and also the impacts at a health district-level. METHODS AND FINDINGS: A previously established Markov macro-simulation model built for the whole New Zealand (NZ) population (Pega et al 2016, Injury Prevention) was enhanced and adapted to a health district level. This district was Counties Manukau District Health Board, which hosts 42,000 people aged 65+ years. A health system perspective was taken and a discount rate of 3% was used for both health gain and costs. Intervention effectiveness estimates came from a systematic review, and NZ-specific intervention costs were extracted from a randomized controlled trial. In the 65+ age-group in this health district, the HSAM program was estimated to achieve health gains of 2800 quality-adjusted life-years (QALYs; 95% uncertainty interval [UI]: 547 to 5280). The net health system cost was estimated at NZ$8.44 million (95% UI: $663 to $14.3 million). The incremental cost-effectiveness ratio (ICER) was estimated at NZ$5480 suggesting HSAM is cost-effective (95%UI: cost saving to NZ$15,300 [equivalent to US$10,300]). Targeting HSAM only to people age 65+ or 75+ with previous injurious falls was estimated to be particularly cost-effective (ICERs: $700 and $832, respectively) with the latter intervention being cost-saving. There was no evidence for differential cost-effectiveness by sex or by ethnicity: Māori (Indigenous population) vs non-Māori. CONCLUSIONS: This modeling study suggests that a HSAM program could produce considerable health gain and be cost-effective for older people at a health district level. Nevertheless, comparisons may be desirable with other falls prevention interventions such as group exercise programs, which also provide social contact and may prevent various chronic diseases.