New Insights in Adherence and Survival in Myotonic Dystrophy Patients Using Home Mechanical Ventilation

Background: Non-invasive home mechanical ventilation (HMV) is a complex treatment in myotonic dystrophy type 1 (DM1) patients, due to a presumed poor adherence, variable symptom improvement, and uncertainty regarding survival benefits. Objectives: We aimed to investigate indications, adherence to HMV and its effects on mortality in a large cohort of DM1 patients. Methods: In this retrospective cohort study, we evaluated 224 DM1 patients. Different groups based on hypercapnia and HMV treatment were compared. Cox regression analyses were performed to compare mortality between different defined groups. Results: 224 patients were analysed of whom 111 started non-invasive HMV. Indications were daytime hypercapnia (n = 75), only nocturnal hypercapnia (n = 33), or other reasons (n = 3). Adequate adherence (≥4 h/night) was found in 84.9% of patients. Adequate ventilation was reached in 86.5% of patients. In 33 patients (29.7%), HMV was stopped prematurely due to not reaching patients' expectations on symptom relief or treatment burden (n = 22), or intolerance (n = 8), or other reasons (n = 3). HMV did not improve survival in daytime hypercapnic patients (p = 0.61) nor in nocturnal hypercapnia patients compared to daytime hypercapnia (p = 0.21). Significant survival benefits after starting HMV were found for patients with HMV adherence ≥5 h/24 h compared to patients who used HMV less. Conclusion: In this large cohort, daytime hypercapnia is the main reason for starting HMV, which is well tolerated and used. Mortality is not associated with the reason why HMV was started, but once started, patients with ≥5 h/24 h adherence have significantly better survival compared to patients who use it less.