Time trends in incidence and characteristics of patients initiating home mechanical ventilation (HMV) in Sweden over 27 years - the population-based DISCOVERY study

Background: Home mechanical ventilation (HMV) is a key treatment to improve outcomes in chronic hypoventilation. This study aimed to evaluate time trends over 27 years in the incidence and prevalence, the diagnosis spectrum, and the characteristics of patients with HMV in Sweden. Methods: National, population-based, longitudinal analysis of the DISCOVERY study of patients initiating HMV between 1996 and 2022. Time trends stratified by the underlying diagnosis group were analysed using descriptive statistics and simple linear regression models. Results: We included 10,555 patients (50.2 % women, aged 63±15 years). Compared to 1996-98, the incidence of HMV increased threefold to 6.6/100,000, and the prevalence increased sixfold to 33.3/100,1000 in 2020-22. The leading indications for incident HMV have shifted from restrictive thoracic diseases (35% in 1996-98) to lung disease (34%), obesity hypoventilation syndrome (OHS) (31%), and amyotrophic lateral sclerosis (ALS) 14% by today. During the study period, the proportion of women increased from 47 to 54%, and the age at initiation of HMV increased from 58±15 to 66±14 years. Lung function measured as vital capacity at treatment start increased significantly in all diagnosis groups but OHS. Conclusion: During the observational time of 27 years, the incidence and prevalence of HMV have increased markedly, and patient demography has changed. Patients are nowadays older when initiating HMV, but treatment is started earlier in the disease trajectory with better lung function at initiation.