OBJECTIVES: Lab-based polysomnography (PSG), for diagnosing obstructive sleep apnoea (OSA), is a subsidised inpatient service in Singapore’s public healthcare institutions (PHIs). The alternative, home sleep test (HST), is cheaper and can be prescribed in the outpatient setting. Following health technology assessment performed by Agency for Care Effectiveness, HST was listed as a subsidised service in PHIs in May 2019. This study aims to assess the impact of the subsidy decision on sleep tests utilisation.

METHODS: We conducted an interrupted time series (ITS) analysis using sleep tests utilisation data submitted by PHIs from January 2018 to June 2021. Segmented regression models were used to assess the degree of level change (LC) and trend change (TC) of HST and PSG. Data points during Singapore’s most stringent COVID-19 restrictions were modelled as “wild” points to account for drastic reduction of elective procedures. Autocorrelation was tested and corrected by including an autoregressive or moving average term in the models.

RESULTS: Subsidy implementation increased the use of HST, from 12% of all sleep tests pre-subsidy to 26% post-subsidy. Despite multiple periods of interruptions, associated with COVID-19 restrictions, ITS showed subsidy implementation led to significant level change in HST utilisation [LC 36.1 (95% CI: 15.1 - 57.2); TC -0.5 (95% CI: -2.3 - 1.4)]. There was also a trend towards reduction in PSG, though this did not reach statistical significance [LC -44.3 (95% CI: -126.6 - 38.2); TC -2.0 (95% CI: -11.6 - 7.7)]. As HST is much cheaper than PSG, total charge avoided by the healthcare system in 10 years is projected to be in the range of SGD9 million to SGD14 million. CONCLUSION: Extension of subsidy to HST appeared to have improved accessibility of sleep tests for OSA diagnosis and resulted in cost saving to Singapore’s healthcare system.