Medline ® Abstracts for References 20-23

BACKGROUND: The relationship of weight changes to the incidence, progression, and remission of sleep-disordered breathing (SDB) is not well defined. This study aims to determine the relationship between change in weight and progression or remission of SDB by polysomnography.

METHODS: We performed a longitudinal cohort study of the cardiovascular consequences of sleep apnea in diverse US communities. Sleep apnea and polysomnographic indicators of SDB were assessed 5 years apart.

RESULTS: A total of 2968 men and women (mean age, 62 years) participated in the study. Men were more likely to have an increase in Respiratory Disturbance Index (RDI) with a given increase in weight than were women, and this was not explained by differences in starting weight, waist circumference, age, or ethnicity. In a linear regression analysis, both men and women had a greater increase in RDI with weight gain than a decrease in RDI with weight loss. In a categorical analysis of larger degrees of change, this sex difference was also evident. Associations were similar in diverse ethnic groups. However,SDB progressed over time, even in those with stable weight.

CONCLUSION: Modest changes in weight were related to an increase or decrease in SDB, and this association was stronger in men than in women.

CONTEXT: Excess body weight is positively associated with sleep-disordered breathing (SDB), a prevalent condition in the US general population. No large study has been conducted of the longitudinal association between SDB and change in weight.

OBJECTIVE: To measure the independent longitudinal association between weight change and change in SDB severity.

DESIGN: Population-based, prospective cohort study conducted from July 1989 to January 2000.

SETTING AND PARTICIPANTS: Six hundred ninety randomly selected employed Wisconsin residents (mean age at baseline, 46 years; 56% male) who were evaluated twice at 4-year intervals for SDB.

MAIN OUTCOME MEASURES: Percentage change in the apnea-hypopnea index (AHI; apnea events + hypopnea events per hour of sleep) and odds of developing moderate-to-severe SDB (defined by an AHI>or =15 events perhour of sleep), with respect to change in weight.

RESULTS: Relative to stable weight, a 10% weight gain predicted an approximate 32% (95% confidence interval [CI], 20%-45%) increase in the AHI. A 10% weight loss predicted a 26% (95% CI, 18%-34%) decrease in the AHI. A 10% increase in weight predicted a 6-fold (95% CI, 2.2-17.0) increase in the odds of developing moderate-to-severe SDB.

CONCLUSIONS: Our data indicate that clinical and public health programs that result in even modest weight control are likely to be effective in managing SDB and reducing new occurrence of SDB.

In this study we report on a long-term follow-up of 14 morbidly obese sleep apneic patients, 11 of whom were male and 3 female. The mean age was 46 +/- 8.5 years. These patients had undergone weight reduction surgery. Before surgery, body mass index (BMI) and apnea index (AI) were 45 +/- 7.2 kg/m2 and 40 +/- 28.8 (SD) h-1, respectively. Four and a half months after surgery (range, 2 to 7 months), both BMI and AI significantly decreased to 33 +/- 7.5 kg/m2 and 11 +/- 16.4 h-1, respectively. Seven and half years after surgery (range, 5 to 10 years), BMI increased only slightly to 35 +/- 6.0 kg/m2 (p>0.2), while AI increased significantly to 24 +/- 23 h-1 (p<0.05). There were poor and insignificant correlations between changes in BMI and AI prior to 4.5 months after operation (r = 0.23; p>0.4). and 4.5 months to 7.5 years after operation (r = 0.41; p>0.1). We conclude that morbid obesity is not the only causative factor in the sleep apnea syndrome for these patients. Weight reduction surgery alone does not "cure" their sleep apnea, and they are still at risk.