Sleep Apnea and 20-Year Follow-Up for All-Cause Mortality, Stroke, and Cancer Incidence and Mortality in the Busselton Health Study Cohort
What is the effect of obstructive sleep apnea (OSA) on all-cause death, stroke, and cancer death in a community population?
The authors studied a single community in the West of Australia with 400 residents participating in long-term follow-up. OSA was diagnosed after a single night home-monitored sleep study. Follow-up deaths and hospitalizations were obtained from a national database registry. Subjects were excluded for prior stroke or cancer history. OSA treatment was recommended, but there were no data on compliance or whether or not OSA was treated.
Follow-up was based on 397 middle-aged people, average ages 52-55 years (102 women: 26%). Moderate or severe OSA was present in 18 (4.6%) people, mild OSA in 81 (20.6%), and no OSA in 294 (74.8%). The analysis had 7,358 person-years of observation. There were 77 deaths (19.6%), 103 cardiovascular events (26.2%; 17 fatalities, 31 strokes, 59 coronary heart disease), and 125 cancer events (32.1%; 39 fatalities). In fully adjusted models (including obesity), moderate-to-severe OSA was significantly associated with all-cause mortality (hazard ratio [HR], 4.2; 95% confidence interval [CI], 1.9-9.2), cancer mortality (HR, 3.4; 95% CI, 1.1-10.2), incident cancer (HR, 2.5; 95% CI, 1.2-5.0), and stroke (HR, 3.7; 95% CI, 1.2-11.8), but not significantly with cardiovascular disease (HR, 1.9; 95% CI, 0.75-4.6) or coronary heart disease incidence (HR, 1.1; 95% CI, 0.24-4.6). Mild sleep apnea was associated with a halving in mortality (HR, 0.5; 95% CI, 0.27-0.99).
The authors concluded that moderate-to-severe OSA is independently associated with a large increased risk of all-cause mortality, incident stroke, and cancer incidence and mortality in a community-based cohort. Mild OSA does not increase mortality and may in fact protect people.
Significant evidence exists linking OSA to hypertension, stroke, and increased risk of mortality. The prevalence of OSA in this cohort is no surprise. However, what is presently mounting is evidence that OSA may be linked to cancer as well. The estimate reported here for cancer mortality is similar to previous larger cohort studies in the United States and Spain. The mechanism is proposed from animal models due to hypoxia facilitating tumor growth. Despite a lack of specifics on cancer type, this study provides clinicians, who treat patients with OSA, yet another powerful reason to treat this condition.
Keywords: Stroke, Neoplasms, Follow-Up Studies, Polysomnography, Middle Aged, Australia, Coronary Disease, Obesity, Hypertension, Sleep Apnea, Obstructive
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