Comorbid disease drives short-term hospitalization outcomes in patients with multiple sclerosis

Background: Readmission is used as a quality indicator and is the primary target outcome for disease-modifying therapy for Multiple sclerosis (MS). However, data on readmissions for MS patients is limited. Methods: Using the U.S. Nationwide Readmissions Database, we performed a retrospective cohort study of adults hospitalized for MS in 2014. Primary study outcomes were within 30- and 90- day readmission. Descriptive analyses compared patient, clinical, and hospital variables by readmission status. Multivariable logistic regression models estimated the associations between these variables and readmission. Results: Of 16,629 individuals meeting study criteria, most were female (73.7%), ages 35-54 (48.0%), and Medicare program participants (36.8%). 49.7% of MS inpatients had 1-2 comorbid medical conditions; 23.7% had three or more. Having three or more comorbidities associated with increased adjusted odds of 30- day readmission (AOR 1.92, 1.34-2.74). Anemia (AOR 1.62, 1.22-2.14), Rheumatoid arthritis / collagen vascular diseases (AOR 2.20, 1.45-3.33), Congestive heart failure (AOR 2.43, 1.39-4.24), Chronic pulmonary disease (AOR 1.35, 1.02-1.78) Diabetes with complications (AOR 2.27, 1.45-3.56), Hypertension (AOR 1.25, 1.03-1.53), Obesity (AOR 1.35, 1.05-1.73), and Renal failure (AOR 1.68, 1.06-2.67) associated with 30 day readmission. Medicare insurance and non-routine discharge also associated with readmission; patient characteristics (sex, age, socioeconomic status) did not. The most frequent (26.7%) reason for readmission was Multiple Sclerosis. 90-day analyses produced similar findings. Conclusions: Comorbid diseases associate with readmission for persons with multiple sclerosis. Evaluations of the real-world effectiveness for disease-modifying therapies in reducing hospitalizations in MS patients may need to consider comorbid disease burden and management.