Hepatitis C (HCV) causes high rates of liver-related morbidity and mortality. The association between HCV and other common medical conditions has been less well characterized. Further, variations in these HCV associations across health care institutions based on demographic and clinical characteristics have yet to be fully described.
Electronic medical records of two large integrated health care systems (Denver Health [DH] and Kaiser Permanente Colorado [KP]) were queried to identify all HCV-related testing between January 1, 2008-December 31, 2014. The testing cohorts were stratified by evidence of infection (detectable HCV RNA) versus no HCV infection (no antibody detected or detectable antibody but no detectable RNA). Groups were characterized by demographic variables and comorbid conditions as defined by Elixhauser ICD-9 codes. Comorbid conditions associated with HCV infection were analyzed though multivariate logistic regression using a stepwise approach.
In the DH system, 28,849 individuals were tested for HCV, of whom 2,018 (7%) had evidence of current HCV infection. In the KP system, 81, 419 individuals were tested for HCV; 1,644 (2%) had evidence of HCV infection. Among tested individuals in both systems, HCV-infected individuals were older and more often Black and male. Cirrhosis, liver cancer, HIV, renal disease, cardiovascular disease, mental illness, alcohol abuse, tobacco use, illicit drug use and death were significantly more common among HCV-infected individuals (see Table). Diabetes was more common among HCV-infected individuals in the KP system only; COPD was more common among HCV-infected individuals in the DH system only. In multivariate logistic regression analyses, the adjusted odds ratios for cirrhosis, mental illness and liver cancer were statistically significant for HCV-infected individuals while renal disease, cardiovascular disease and death were not significantly associated with HCV infection.
Among individuals tested for HCV in these two large, integrated health care systems, HCV infection was common. While several comorbid conditions were more frequently observed among HCV-infected individuals, multivariate analysis showed significant associations for cirrhosis, liver cancer and mental illness, suggesting the high prevalence of many comorbid conditions among HCV-infected individuals may be more associated with socio-demographic characteristics, substance abuse and other comorbid conditions than with HCV infection directly.