Continuous positive airway pressure devices for the treatment of obstructive sleep apnoea–hypopnoea syndrome: a systematic review and economic analysis

Objectives To determine the clinical effectiveness, safety and cost-effectiveness of continuous positive airway pressure (CPAP) devices for the treatment of obstructive apnoea–hypopnoea syndrome (OSAHS), compared with the best supportive care, placebo and dental devices. Data sources The main search was of fifteen electronic databases, including MEDLINE, EMBASE and the Cochrane Library, up to November 2006. Review methods Randomised controlled trials (RCTs) comparing CPAP with best supportive/usual care, placebo, and dental devices in adults with a diagnosis of OSAHS were included. The primary outcomes of interest were subjective daytime sleepiness assessed by the Epworth Sleepiness Scale (ESS) and objective sleepiness assessed by the Maintenance of Wakefulness Test (MWT) and the Multiple Sleep Latency Test (MSLT). A new economic model was developed to assess incremental cost per quality-adjusted life-year (QALY). The cost-effectiveness of CPAP was compared with that of the use of dental devices and conservative management. The costs and QALYs were compared over a lifetime time horizon. Effectiveness was based on the RCT evidence on sleepiness symptoms (ESS), which was ‘mapped’ to utilities using individual patient data from a subset of studies. Utilities were expressed on the basis of generic HRQoL instruments [the EQ-5D (EuroQoL-5 Dimensions) in the base-case analysis]. The base-case analysis focused on a male aged 50. A series of subgroup and scenario analyses were also undertaken. Results The searches yielded 6325 citations, from which 48 relevant clinical effectiveness studies were identified, 29 of these providing data on daytime sleepiness. The majority of the included RCTs did not report using an adequate method of allocation concealment or use an intention-to-treat analysis. Only the studies using a sham CPAP comparator were double blinded. There was a statistically significant benefit with CPAP compared with control (placebo and conservative treatment/usual care) on the ESS [mean difference (MD) –2.7 points, 95% CI –3.45 to –1.96]. However, there was statistical heterogeneity, which was reduced when trials were subgrouped by severity of disease. There was also a significant benefit with CPAP compared with usual care on the MWT. There was a non-statistically significant difference between CPAP and dental devices (six trials) in the impact on daytime sleepiness (ESS) among a population with moderate symptom severity at baseline (MD –0.9, 95% CI –2.1 to 0.4). A review of five studies evaluating the cost-effectiveness of CPAP was undertaken. All existing cost-effectiveness studies had limitations; therefore a new economic model was developed, based on which it was found that, on average, CPAP was associated with higher costs and benefits than dental devices or conservative management. The incremental cost per QALY gained of CPAP was below £20,000 in the base-case analysis and most alternative scenarios. There was a high probability of CPAP being more cost-effective than dental devices and conservative management for a cost-effectiveness threshold of £20,000 per QALY gained. Conclusions CPAP is an effective and cost-effective treatment for OSAHS compared with conservative/usual care and placebo in populations with moderate to severe daytime sleepiness, and there may be benefits when the disease is mild. Dental devices may be a treatment option in moderate disease but some uncertainty remains. Further research would be potentially valuable, particularly investigation of the effectiveness of CPAP for populations with mild sleepiness and further trials comparing CPAP with dental devices.