Economic Evaluation Of The Treatment Of Obstructive Sleep Apnoea Syndrome In Aotearoa/New Zealand

Some sleep disorders lead to serious consequences for society in the form of increased morbidity and accidents. The most commonly diagnosed and treated sleep disorder in New Zealand and internationally is Obstructive Sleep Apnoea Syndrome (OSAS). The aim of this study was to improve the information available for both clinical and policy decision-makers. An outcome tree and decision analytic model for OSAS were constructed and used to estimate base case costs. Sensitivity analysis using Monte Carlo methods was undertaken. The total base case societal costs of OSAS are $40 million or $419 per case. Direct medical costs were 58% of the total societal costs, direct non medical 13%, indirect 25%, and the intangible costs of loss of life 3%. The incremental net cost of treating OSAS is $389 per case treated. Incremental net direct medical cost per QALY gained (when OSAS is successfully treated) is $94. For 90% of the 10,000 Monte Carlo iterations the total societal cost of treated and untreated OSAS ranged between $33 million and $90 million, the net incremental cost of treatment per case ranged between $338 and $427, and the net direct medical cost per QALY gained ranged between $56 and $310. The study was based on Wellington treatment profiles, treatment availability and uptake, costs and funding and may not be typical of the variety of rural and urban settings throughout New Zealand. The costs of OSAS in our study are conservative; we considered only diabetes and cardiovascular disease, and estimated productivity loss for time off work but not for absenteeism or low productivity while working. This study is the first in New Zealand to attempt to quantify the costs of OSAS and to provide a tool that can be used to investigate treatment options and the impact of sleep disorders on various population groups. As accidents generate 59% of the total costs efforts should be made to reduce this rate.