Can Continuous Positive Airway Pressure Adherence Reduce Bone Loss in Patients with Sleep Apnea?

Abstract

Background: Obstructive sleep apnea (OSA) is associated with increased bone mineral density loss. Hypoxia experienced in the OSA population was suspected to stimulate osteoclast activity and contribute to osteoporosis. Continuous positive air pressure (CPAP) therapy, the first line treatment for OSA, reduces nocturnal hypoxia. Therefore, this study evaluates the potential for CPAP therapy to slow down the process of bone loss. Methods: This is a retrospective cohort study reviewing the electronic medical records of patients between the ages of 45 to 70 years old with the diagnosis of OSA and on CPAP therapy. The OSA diagnosis was supported by a home sleep study, and the CPAP compliance was determined by 70% of usage, or an average of more than 4 hours per day with 5 days in a week. We compared the mean difference of T-score per year on Dual-energy X-ray absorptiometry scans in patients compliant with CPAP treatment and patients not compliant with CPAP, utilizing T-test analysis. Results: There are 113 patients included in the study, with 81 compliant and 32 non-compliant to CPAP therapy. The mean age of the CPAP compliant group (65.7 years) was higher than the non-compliant group (63.2 years). The mean annual change in T-score for lumbar spine, left femur neck, left femur total and left radius were -0.015 ±0.27, -0.003 ±0.19, 0.002 ±0.21, -0.019 ±0.22 respectively in CPAP compliant group, and -0.03 ±0.20, -0.050 ±0.14, -0.014 ±0.17, -0.012 ±0.26 in the non-compliant group. There was no statistical difference in annual bone density changes between the CPAP compliant and non-compliant group. Conclusion: This is the first study evaluating the effect of CPAP therapy on bone health. The mean reduction in T-score in three out of four areas each year was less in the CPAP compliant group although not reaching statistical significance, possibly limited by the small sample size. Further prospective study and larger sample size might reveal the effect of CPAP on reducing the speed of bone loss in OSA populations.