Medline ® Abstracts for References 52-54

BACKGROUND: Obstructive sleep apnea (OSA) is a risk factor for cardiovascular death in men, but whether it is also a risk factor in women is unknown.

OBJECTIVE: To investigate whether OSA is a risk factor for cardiovascular death in women and assess whether continuous positive airway pressure (CPAP) treatment is associated with a change in risk.

DESIGN: Prospective, observational cohort study.

SETTING: 2 sleep clinics in Spain.

PATIENTS: All women consecutively referred for suspected OSA between 1998 and 2007.

INTERVENTION: Every woman had a diagnostic sleep study. Women with an apnea-hypopnea index (AHI) less than 10 were the control group. Obstructive sleep apnea was diagnosed when the AHI was 10 or higher (classified as mild to moderate [AHI of 10 to 29]or severe [AHI≥30]). Patients with OSA were classified as CPAP-treated (adherence≥4 hours per day) or untreated (adherence<4 hours per day or not prescribed). Participants were followed until December 2009.

MEASUREMENTS: The end point was cardiovascular death.

RESULTS: 1116 women were studied (median follow-up, 72 months [interquartile range, 52 to 88 months]). The control group had a lower cardiovascular mortality rate (0.28 per 100 person-years [95% CI, 0.10 to 0.91]) than the untreated groups with mild to moderate OSA (0.94 per 100 person-years [CI, 0.10 to 2.40]; P = 0.034) or severe OSA (3.71 per 100 person-years [CI, 0.09 to 7.50]; P<0.001). Compared with the control group, the fully adjusted hazard ratios for cardiovascular mortality were 3.50 (CI, 1.23 to 9.98) for the untreated, severe OSA group; 0.55 (CI, 0.17 to 1.74) for the CPAP-treated, severe OSA group; 1.60 (CI, 0.52 to 4.90) for the untreated, mild to moderate OSA group; and 0.19 (CI, 0.02 to 1.67) for the CPAP-treated, mild to moderate OSA group.

LIMITATION: The study was observational and not randomized, and OSA was diagnosed by 2 different methods.

CONCLUSION: Severe OSA is associated with cardiovascular death in women, and adequate CPAP treatment may reduce this risk.

PRIMARY FUNDING SOURCE: None.

STUDY OBJECTIVES: The aims of this study were to analyze mortality in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) treated with positive airway pressure (PAP) and to know whether PAP compliance affects survival, as well as to investigate the prognostic value of several pretreatment variables.

DESIGN AND PATIENTS: A study was made of an historical cohort of 871 patients in whom OSAHS had been diagnosed by sleep study between January 1994 and December 2000 and who had been treated with PAP. Patients were followed up until December 2001. The mean (+/- SD) age of the group was 55.4 +/- 10.6 years, the mean apnea-hypopnea index (AHI) 55.1 +/- 28.7, and 80.9% were men. To assess whether mortality was influenced by PAP therapy compliance, patients were assigned to one of the following compliance categories:<1 h/d; 1 to 6 h/d; or>6 h/d. Survival rates were calculated according to the Kaplan-Meier method. Survival curves were compared with the log-rank test and the trend test, when necessary. Univariate and multivariate analyses using a time-dependent Cox model were performed to elicit which variables correlated with mortality.

SETTING: Outpatient sleep disorders unit.

RESULTS: By the end of the follow-up period (mean duration, 48.5 +/- 22.7 months), 46 patients had died. The 5-year cumulative survival rates were significantly lower in patients who did not use PAP (compliance<1 h) than in those who used the device for>6 h/d (85.5% [95% confidence interval (CI), 0.78 to 0.92]vs 96.4% [95% CI, 0.94 to 0.98; p<0.00005]) and 1 to 6 h/d (85.5% [95% CI, 0.78 to 0.92]vs 91.3% [ 95% CI, 0.88 to 0.94; p = 0.01]), respectively. A trend in survival rates across the groups was identified (p = 0.0004). The main cause of death in 19 cases was cardiovascular disease (CVD). Variables that independently correlated with mortality in the multivariate analysis were the following PAP use categories: compliance for>6 h/d (odds ratio [OR], 0.10; 95% CI, 0.04 to 0.29); compliance for 1 to 6 h/d (OR, 0.28; 95% CI, 0.11 to 0.69); arterial hypertension (AHT) [OR, 3.25; 95% CI, 1.24 to 8.54]; age (OR, 1.06; 95% CI, 1.01 to 1.10); and FEV1 percent predicted (OR, 0.96; 95% CI, 0.94 to 0.98).

CONCLUSION: Mortality rates in OSAHS patients who did not receive PAP therapy were higher compared with those treated with PAP and were moderately or highly compliant with therapy. A trend in survival across compliance categories was found. Patients died mainly from CVD. Categories of PAP compliance, AHT, age, and FEV1 percent predicted were the variables that independently predicted mortality.

The aim of this study was to determine mortality in patients with sleep apnoea/hypopnoea syndrome (SAHS) according to the treatments employed and comorbidity. An historical cohort of patients with SAHS diagnosed at a university hospital between 1982 and 1992 and followed until 1996 was studied. From a total of 475 SAHS patients, 444 (94%), with a mean+/-SD apnoea/hypopnoea index at diagnosis of 55+/-27, were located and included in the study. SAHS treatments employed were: surgery (88), weight loss (134), continuous positive airway pressure (124) and 98 patients were not treated. By the end of follow-up, 49 patients had died. According to Cox regression analysis, mortality in treated patients was lower than in those not treated, but higher in those with a history of severe chronic obstructive pulmonary disease. Mortality in nontreated patients compared with that of the general population, adjusted for age and sex, showed excessive mortality, which decreased in treated patients. Stratification by age showed a greater mortality rate ratio in patients<50 yrs. These findings were maintained when mortality from cardiovascular causes was compared. In conclusion, a rise in mortality was found in nontreated sleep apnoea/hypopnoea syndrome patients compared with the general population, whereas mortality in those treated for sleep apnoea/hypopnoea syndrome did not differ significantly from that of the general population.