Estimating the economic cost of adults living with genetic muscle disorders in New Zealand : A cost-of-illness study

Abstract

Aim: The primary aim of this research was to determine the costs associated with genetic muscle disorders (GMDs) among adults in New Zealand. This study also aimed to highlight the main cost drivers for GMDs and their subgroups in New Zealand, and determine the clinical, socioeconomic and healthcare system factors that predict the level of treatment cost. Methods: A prevalence-based cost-of-illness model was developed using a bottom-up and retrospective approach from a societal perspective. Population-based data containing electronic hospital records and self-reported health service usage from the Genetic Muscle Disorder Prevalence study were utilised in this research. Multivariable linear regression analyses were conducted to determine which variables predicted higher direct and total costs for people with GMDs. Results: Eight hundred and nine cases were eligible in the data set; 490 (61%) provided consent to be included in this cost-of-illness study. The mean age was 45.6 years, ranging from 16 to 90 years. The most common GMD in the study was myotonic dystrophy with 202 patients (41%). Total direct healthcare costs per person were NZ$29,762 (95%CI $24,354-$35,224) and formal care was the largest cost component (67%) of direct healthcare costs. The total direct non-healthcare costs per person was NZ$33,090 (95%CI 28,207-$38,517) and informal care was the largest cost component (74%) of this category. Indirect costs were estimated as temporary productivity loss due to missed workdays or reduced work hours. Fifty-four (11%) of the cohort reported this productivity loss which was valued at NZ$11,466 (95%CI $7,695-$16,141). The total per person per annum cost of GMDs in New Zealand was estimated at NZ$64,114 (95% CI $57,045-$73,777). When informal care was excluded, the total one-year per person cost reduced to NZ$39,789 (95%CI $34,717-$46,983). The main cost drivers of GMDs and for the six common subtypes of GMDs were formal and informal care, followed by medical aids and hospital admissions. Variables of high predictors of cost were being in employment, having a manual or electric wheelchair, the need for ventilatory support and having at least one co-morbid condition. Conclusion: This study has highlighted that the economic burden of GMDs among adults in New Zealand is substantial. Consistent with previous literature, informal care was found to be a large driver of costs and a significant area of unmet need. Quantifying this high cost stresses the importance and need of providing adequate support for informal caregivers of people with GMDs.