Comorbidities and co-medications in populations with and without chronic hepatitis C virus infection in Japan between 2015 and 2016

BACKGROUND: Direct-acting anti-viral agents have improved the treatment of chronic hepatitis C virus (HCV) infection, but this treatment is challenging for patients using co-medications because of potential drug–drug interactions. This study aimed to examine the comorbidities and co-medications of Japanese chronic HCV patients by age group, compared with a non-HCV patient population. METHODS: This was a retrospective observational study using a hospital-based medical claims database. We extracted data of patients with chronic HCV aged ≥18 years, and age-, sex-, and hospital-matched patients without HCV, for the period from January 2015 to November 2016, and then examined chronic comorbidities, long-term co-medications, and medications prescribed at least once during the study period. RESULTS: We analysed data from 128,967 chronic HCV patients and 515,868 non-HCV patients. The median age was 70 years, and 51.0% of patients were male. More chronic HCV patients than non-HCV patients (70.5% vs. 47.1%) had at least one comorbidity, and older patients had more comorbidities than younger patients. The most common comorbidities in chronic HCV patients were diseases of oesophagus, stomach and duodenum (41.7%), followed by hypertensive diseases (31.4%). Chronic HCV patients used co-medications more commonly than non-HCV patients, and older patients used more co-medications. The most common long-term co-medications in chronic HCV patients were proton pump inhibitors (14.0%), which were prescribed to 31.9% of chronic HCV patients at least once during the study period. CONCLUSIONS: Patients with chronic HCV in Japan had more comorbidities than patients without chronic HCV regardless of age. Particularly older patients, who constitute the majority of the HCV patient population in Japan, commonly had multiple comorbidities and used co-medications. To optimise HCV treatment, physicians need to know the exact medication profiles of patients and take appropriate action to manage drug–drug interactions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12879-018-3148-z) contains supplementary material, which is available to authorized users.