Educational level, marital status and sex as social gender discharge determinants in chronic obstructive pulmonary disease exacerbations: a time-to-event analysis

The aim of this study is to evaluate, in patients hospitalized for COPD exacerbation, how educational level, marital status and sex (social gender indicators) affect the home discharge probability (main effects) and how interact with each other in affecting this probability (effect modification). Data for all patients discharged with a principal diagnosis of COPD with exacerbation (ICD-9 491.21) by Apulian hospitals between 2013 and 2017 were retrieved from the National Hospital Discharge Register Database. A multivariable multi-stratified frailty cox proportional-hazard regression with interaction terms was fitted in order to assess the effect of sex, educational level and marital status on the time-to-event for home discharge through the estimation of hazard ratios. Adjusting for several patient and hospitalization characteristics and for healthcare facilities, low educational level (<8 years of schooling) is associated with a lower probability of being discharged to home in both sexes and in all marital status categories (HR 0.92, 95%CI 0.87-0.97, p=0.0020). Female sex is associated with a lower probability of being discharged to home only in married patients (HR 0.83, 95%CI 0.78-0.88, p<0.0001). Marital status different from married is associated with a lower probability of being discharged to home only in male patients, in particular single patients (HR 0.82, 95%CI 0.74-0.92, p=0.0009), separated or divorced patients (HR 0.71, 95%CI 0.58-0.86, p=0.0005) and widowed patients (HR 0.87, 95%CI 0.80-0.95, p=0.0018). Differently from findings about protective effect of education, the evidence of different effects of sex on home discharge probability among civil statuses and of different effect of civil status among sexes is supposed to be a proxy for social gender health and healthcare inequalities.