Health technology assessment of continuous positive airway pressure devices in sleep apnoea hypopnoea syndrome
A. 1 Background The need to assess safety as well as clinical and economic effectiveness of health care innovations and thus prioritise health care provision, created the need for structured health technology assessment (HTA) programs [Gafni et al. 1993b; Henshall et al. 1997; Stevens et al. 20041. Sleep apnoea hypopnoea syndrome (SAHS) affects 2-4% of the adult population [Young et al. 1993] who are disabled by daytime dysfunction [Hardinge et al. 1995; Johns 1993b; Mitler 1993; Sauter et al. 200l and a heightened mortality and morbidity [Greenberg et al. 1995; Kiely et al. 2000; Peker et al. 1999; Sanner et al. 1997; Tremel et al. 1999; Wilcox et al. 1998; Moruzzi et al 1999; Malone et al. 1991]. The advent of continuous positive airway pressure devices (CPAP) [Sullivan et al 1981] made it possible to treat safely, patients over a wider spectrum of disease severity [Borak et al. 1996; Mar et al. 2003; Engleman et al 1997a], yet its diffusion and adoption appears to follow a heterogenous pattern. A. 2 Study design A retrospective case-control study of 603 SAHS patients was followed by a prospective, randomised, parallel group trial (RCT) of CPAP compared to lifestyle intervention (including weight reduction and sleep hygiene strategy) comparing clinical, health related quality of life (HRQL) and cost-utility ratios (CUR). The final study is a qualitative survey assessing the factors influencing the diffusion and adoption of CPAP among 303 Primary care trusts (PCT) and 261 Respiratory physicians in the UYA. 3 Results SAHS patients had a (5x) higher risk of death and (2x) of hypertension, compared to controls. Among 71 SAHS patients in the RCT, those on CPAP demonstrated greater clinical effectiveness (sleep latency, apnoea hypopnoea index, excessive daytime sleepiness & neuropsychiatriefunction) and HRQL (social functioning, mental health & energylvitality) compared to lifestyle intervention. Utilities improved on CPAP and the CUR were lower (E'716-E2027 vs. F-326444243). The diffusion survey demonstrated that the characteristics of CPAP as an innovation, would favour its adoption compared to alternative therapies, except in patient tolerability (PCT respondents). However there appeared to be no regular system for the diffusion of innovation knowledge within the NHS and hindrances in SAHS management due to deficiencies in resources, specialists and facilities. A. 4 Conclusions The results presented in this thesis provide a logical framework for the assessment of the progression of an innovation from the stage of establishing the clinical burden of disease and treatment needs, to its adoption and may help identify potentially modifiable factors in slow diffusion scenarios.