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BMJ No 7104 Volume 315 Letters Saturday 9 August 1997 Obstructive sleep apnoeaFalse impression of objectivity may deny patients affordable treatmentEditor,In their review of the clinical impact of obstructive sleep apnoea and the utility of treatment with nasal continuous positive airways pressure John Wright and colleagues make some important points but give a false impression of objectivity.(1) Their criteria for excluding abstracts and letters are vague, and the predetermined validity criteria for papers were not well defined - disagreements between the two assessors had to be resolved by a third person. There is evidence of bias, particularly in the discussion on mortality. Two studies in which the design would be unlikely to show any effect are highlighted as showing no significant association between obstructive sleep apnoea and premature death(2,3); another in which the apnoea index was a predictor of excess mortality(4) is only briefly mentioned and is qualified by the negative statements that the duration of apnoea was not a predictor of mortality and that the excess deaths were not due to heart or lung causes. The important point that the apnoea index was a predictor of premature death was not discussed. The concept that obstructive sleep apnoea varies from being normal to a life threatening condition is unacknowledged. Results of studies in which most of the patients had only mild disease were used to suggest that there is no link between obstructive sleep apnoea and medical problems. Similarly the authors seem unaware of current medical practice when they state that continuous positive airways pressure is the recommended initial treatment for obstructive sleep apnoea; simple measures such as weight loss are usually tried first. We are also concerned by the accuracy of the review. There are three
errors in the description of our study on nasal continuous positive
airways pressure and obstructive sleep apnoea.(5) In table 4
of John Wright and colleagues' paper(1) the desaturation
index for patients with mild obstructive sleep apnoea should be 8, not
38; disruptive daytime sleepiness was an indication for starting
treatment with continuous positive airways pressure; and 'no change
in ... symptoms' should read 'no new unrelated s The impression of objectivity and accuracy and of a scientific approach
in this review is illusory. The underlying assumption that clinicians
are widely using nasal continuous positive airways pressure in patients
without important symptoms is unjustified. It would be unfortunate if
this review led to patients being denied a cheap and effective
treatment that could prevent them from remaining excessively sleepy for
the rest of their lives and running an increased risk of premature
death.
John Shneerson
Papworth Hospital,
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 Bliwise D L, Bliwise N G, Partinen M, Pursley A M, Dement W C. Sleep
apnea and mortality in an aged cohort. Am J Public
Health 1988;78:544-7.
3 Maut A, King M, Saunders N A, Pond C D, Goode E, Hewitt H.
Four-year follow-up of mortality and sleep-related respiratory
disturbance in non-demented seniors. Sleep
1995;18:433-8.
4 Lavie P, Hever P, Peled R, Berger I, Yoffe N, Zomer J, et al.
Mortality in sleep apnoea patients; multivariate analysis of risk
factors. Sleep 1995;18:149-57.
5 Smith I E, Shneerson J M. Is the SF36 sensitive to sleep
disruption? A study in subjects with sleep apnoea. J Sleep
Res 1995;4:183-8.
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