CPAP therapy of OSA is associated with decreased BMI, studies to date do not suggest a specific pattern, and overall, suggest long-term stability in body mass after one year. We have found that body mass increases in the majority of patients with OSA treated with CPAP for 4 weeks.
Retrospective analysis of 218 consecutive patients treated for sleep apnea at a community-based sleep center.
152 patients met criteria for study conclusion. After 1 month of CPAP treatment, 119 subjects (78%) gained weight. Weight gain occurred in 81% of men and 73% of women. As a group, subjects on CPAP gained 1.4 ± 0.2 kg (mean ± s.e.). Epworth sleepiness scale was reduced after one month of CPAP therapy. There was no correlation between gain in body mass and measured parameters. A subgroup of 71 patients remained on therapy. They demonstrated gain in mass at 4 weeks, which did not persist at 6 months.
CPAP treatment of OSA is associated with gain in body mass at 1 month but not after 6 months of therapy. Etiology and significance of this gain in mass remains unknown. We suspect some gain is due to increased vascular volume.
Increase in body mass after one month of CPAP treatment of OSA, which does not persist after 6 months of treatment. Short-term change in body mass might be multifactorial, but we suspect an increase in vascular volume occurs soon after initiation of CPAP therapy. As visceral adiposity seems to decrease after 6 months of CPAP therapy, an increase in vascular volume could persist in the absence of a persistent increase in body mass. Short-term gain in body mass might represent an integrated measure of cardiovascular response to CPAP therapy, and prospective study should be undertaken to assess time course and physiological mechanisms.
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