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BMJ No 7104 Volume 315 Letters Saturday 9 August 1997 Obstructive sleep apnoeaEvidence for efficacy of continuous positive airways pressure is compellingEditor,The review by John Wright and colleagues of the complications of obstructive sleep apnoea,(1) a reincarnation of a previous publication,(2) concluded that the relation between obstructive sleep apnoea and hypertension, coronary heart disease, stroke, and premature death are poorly established; this conclusion has been stated many times by other authors, including us.(3) What was new was their inference that the treatment of obstructive sleep apnoea with continuous positive airways pressure is difficult to justify because much of the published evidence is poor or inconclusive. This is wrong since it fails to appreciate that patients are treated for disabling daytime somnolence and not for the risk of cardiovascular disease or premature death. Weak data on cardiovascular aspects are largely irrelevant to the assessment of treatment for this disorder. How could Wright and colleagues have wandered so far from the mark? We suspect that their error resulted from the simple mistake of reviewing studies and assuming that because most revolve around the cardiovascular-mortality debate, this must be the most important area to consider. This would be a natural mistake for those with no experience of the disease and its management, who thus have no idea that it is mainly hypersomnolence which disturbs patients. There is considerable published work on the cardiovascular and mortality aspects of this disease precisely because this is a highly contentious subject. There are few randomised controlled data on the efficacy of continuous positive airways pressure for overwhelming somnolence because the therapeutic response is so compelling in case reports. Those of us who treat these patients have seen the predicted improvements when patients woken from sleep over 300 times a night for years finally regain normal sleep patterns with continuous positive airways pressure. Perhaps naively we had never expected anyone to question this; neither had we expected the opinions of people with no clinical experience of a complex disease to be taken seriously. Until there is a fully informed view that includes the skill and
experience of those who understand the disease, it would be wrong (and
negligent) to base purchasing decisions on this incomplete assessment.
An evidence based approach is crucial to clinical medicine and sensible
purchasing decisions; it should not be brought into disrepute by being
used in an unbalanced J R Stradling
Oxford Sleep Unit,
References
1 Wright J, Johns R, Watt I, Melville A, Sheldon T. Health
effects of obstructive sleep apnoea and the effectiveness of continuous
positive airways pressure: a systematic review of the research
evidence. BMJ 1997;314:851-60. (22 March.)
2 Wright J, Dye R. Systematic review on obstructive sleep
apnoea: its effect on health and benefit of treatment. Leeds:
Nuffield Institute for Health, 1996.
3 Working Group on OSA and Hypertension, Carlson J, Davies R,
Ehlenz K, Grunstein R, Hedner J, Podszus T, et al. Obstructive sleep
apnea and blood pressure elevation. What is the relationship?
Blood Pressure 1993;2:166-82.
4 Stradling J R. Sleep apnoea and the misuse of evidence based
medicine. Lancet 1997;349:201-2.
5 Sackett D L, Rosenburg W C, Muir Gray J A, Haynes R B, Richardson
W S. Evidence based medicine: what it is and what it isn't.
BMJ 1996;312:71-2.
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