The prevalence of chronic diseases and multimorbidity in primary care practice: a PPRNet report.

INTRODUCTION Multimorbidity (multiple chronic illnesses) greatly affects the delivery of health care and assessment of health care quality. There is a lack of basic epidemiologic data on multimorbidity in the United States. This article addresses the prevalence of 24 chronic illnesses and multimorbidity from primary care practices across the United States. METHODS This cross-sectional study was conducted in the PPRNet, a practice-based research network among 226 practices in 43 states that maintains a clinical database derived from a common electronic health record. Practices providing data as of October 1, 2011, and their active adult patients comprised the population used for analyses. The prevalence of each chronic illness and multimorbidity were calculated. RESULTS Included in these analyses were 148 practices with 667,379 active patients. Median prevalence across practices ranged from 35.8% for hypertension to 0.23% for Parkinson disease, with wide variability among practices for all conditions. Multimorbidity increased steeply with age, leveling off at age 80; overall, 45.2% of patients had more than one chronic illness. CONCLUSION Multimorbidity is a prevalent problem in primary care practice, a finding with implications for health care delivery and payment, quality assessment, and research.