Impact of Comorbidity on Hospitalization and Emergency Room Visits in Adults With Diabetes: A Longitudinal Study of Alberta's Tomorrow Project.

Objective: Our aim in this study was to characterize the impact of comorbidities, including number and types, on hospitalization and emergency room (ER) visits in people with diabetes.

Methods: Incident cases of diabetes from Alberta's Tomorrow Project with >24 months of follow-up were included. Comorbidities, classified by Elixhauser conditions, were updated every 12 months after diagnosis. A generalized estimating equation model was used to examine the association (by incidence rate ratio [IRR]) between time-varying comorbidity profile and hospitalization and ER visits per year of follow-up after adjusting for sociodemographic factors, lifestyle behaviours, and historic health-care utilization in the previous 5 years.

Results: Among 2,110 incident cases of diabetes (51.0% females; median age at diagnosis: 59.5 years; median follow-up: 7.19 years), the average number of Elixhauser comorbidities was 1.9±1.6 in the first year of diagnosis and 3.3±2.0 in year 15 after diagnosis. The number of comorbidities in the previous year was positively associated with risk of hospitalization (IRR=1.33 [95% confidence interval {CI}: 1.04 to 1.70] and 2.14 [95% CI: 1.67 to 2.74] for 1 or 2 and ≥2 comorbidities, respectively) and ER visits (IRR=1.31 [95% CI: 1.15 to 1.50] and 1.62 [95% CI: 1.41 to 1.87] for 1 or 2 and ≥2 comorbidities, respectively) in the subsequent year. Cardiovascular diseases, peripheral vascular diseases, cancer, liver disease, fluid and electrolyte disorders, and depression were the conditions most typically associated with increased health-care utilization.

Conclusions: The number of comorbidities was a major risk factor of health-care utilization for people with diabetes. Vascular diseases, cancer, and conditions closely related to diabetic frailty (e.g. fluid and electrolyte disorders and depression) were the main drivers of hospital care and ER visits.