title: Estimating the prevalence of comorbid conditions and their effect on health care costs in patients with diabetes mellitus in Switzerland.
abstract: BACKGROUND
  Estimating the prevalence of comorbidities and their associated costs in patients with diabetes is fundamental to optimizing health care management. This study assesses the prevalence and health care costs of comorbid conditions among patients with diabetes compared with patients without diabetes. Distinguishing potentially diabetes- and nondiabetes-related comorbidities in patients with diabetes, we also determined the most frequent chronic conditions and estimated their effect on costs across different health care settings in Switzerland.
  
  
  METHODS
  Using health care claims data from 2011, we calculated the prevalence and average health care costs of comorbidities among patients with and without diabetes in inpatient and outpatient settings. Patients with diabetes and comorbid conditions were identified using pharmacy-based cost groups. Generalized linear models with negative binomial distribution were used to analyze the effect of comorbidities on health care costs.
  
  
  RESULTS
  A total of 932,612 persons, including 50,751 patients with diabetes, were enrolled. The most frequent potentially diabetes- and nondiabetes-related comorbidities in patients older than 64 years were cardiovascular diseases (91%), rheumatologic conditions (55%), and hyperlipidemia (53%). The mean total health care costs for diabetes patients varied substantially by comorbidity status (US$3,203-$14,223). Patients with diabetes and more than two comorbidities incurred US$10,584 higher total costs than patients without comorbidity. Costs were significantly higher in patients with diabetes and comorbid cardiovascular disease (US$4,788), hyperlipidemia (US$2,163), hyperacidity disorders (US$8,753), and pain (US$8,324) compared with in those without the given disease.
  
  
  CONCLUSIONS
  Comorbidities in patients with diabetes are highly prevalent and have substantial consequences for medical expenditures. Interestingly, hyperacidity disorders and pain were the most costly conditions. Our findings highlight the importance of developing strategies that meet the needs of patients with diabetes and comorbidities. Integrated diabetes care such as used in the Chronic Care Model may represent a useful strategy.
authors.affiliation: Department of Health Sciences, Helsana Group, Zürich, Switzerland.
authors.forename: Carola A
authors.initials: CA
authors.lastname: Huber
authors.affiliation: Department of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Diem
authors.affiliation: Institute of Social and Preventive Medicine, University of Zürich, Zürich, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schwenkglenks
authors.affiliation: Department of Health Sciences, Helsana Group, Zürich, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Rapold
authors.affiliation: Department of Health Sciences, Helsana Group, Zürich, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Reich
keywords: chronic diseases; comorbidity; costs; diabetes