Gender Differences in Outcomes of Ambulatory and Hospitalized Patients With Obesity Hypoventilation Syndrome.

Background: Obesity hypoventilation syndrome (OHS) is associated with high morbidity and mortality. There are few data on whether there are gender differences in outcomes.

Research question: Is female gender associated with worse outcomes in ambulatory and hospitalized patients with OHS?

Study design and methods: Post hoc analyses were performed on 2 separate OHS cohorts: (1) stable ambulatory patients from the 2 Pickwick randomized controlled trials; and (2) hospitalized patients with acute-on-chronic hypercapnic respiratory failure from a retrospective international cohort. We first conducted bivariate analyses of baseline characteristics and therapeutics between genders. Variables of interest from these analyses were then grouped into linear mixed effects models, Cox proportional hazards models, or logistic regression models to assess the association of gender on various clinical outcomes.

Results: The ambulatory prospective cohort included 300 patients (64% female), and the hospitalized retrospective cohort included 1,162 patients (58% female). For both cohorts, women were significantly older and more obese than men. Compared with men, baseline Paco₂ was similar in ambulatory patients but higher in hospitalized women. In the ambulatory cohort, in unadjusted analysis, women had increased risk of emergency department visits. However, gender was not associated with the composite outcome of emergency department visit, hospitalization, or all-cause mortality in the fully adjusted model. In the hospitalized cohort, prescription of positive airway pressure was less prevalent in women at discharge. In unadjusted analysis, hospitalized women had a higher mortality at 3, 6, and 12 months following hospital discharge compared with men. However, after adjusting for age, gender was not associated with mortality.

Interpretation: Although the diagnosis of OHS is established at a more advanced age in women, gender is not independently associated with worse clinical outcomes after adjusting for age. Future studies are needed to examine gender-related health disparities in diagnosis and treatment of OHS.