Clinical characteristics in patients with non-alcoholic steatohepatitis in Japan: a case-control study using a 5-year large-scale claims database

ObjectivesTo examine the clinical characteristics of patients with non-alcoholic steatohepatitis (NASH) and associated comorbidities. DesignA case-control study using the national health insurance and the long-term elderly health insurance claims database. SettingEligible patients diagnosed with NASH (ICD-10 K-75.8, other inflammatory liver disease or K-76.0, other fatty liver) between April 2015 and March 2020 were included. ParticipantsPatients who met the diagnostic definitions for NASH (n=545) were matched with non-NASH controls (n=185 264) and randomly selected according to sex, birth year and residential area. InterventionsNo interventions were made. Primary and secondary outcome measuresORs were estimated for the relationship between patient background, such as age and sex, body mass index (BMI), NASH-related comorbidities and lifestyle-related diseases. ResultsIn total, 545 patients with NASH (38.3% men) and 185 264 non-NASH controls (43.2% men) were identified, with median ages of 68 (IQR 63.0-75.0) and 65 (IQR 44.0-74.0) years, respectively. BMI was significantly higher in patients with NASH than in controls (25.8 kg/m(2) vs 22.9 kg/m(2), p<0.001). The proportions of women, patients with hypertension, patients with dyslipidaemia and patients with type 2 diabetes were higher in the NASH group. In addition, NASH was associated with an increased risk of hepatic cirrhosis (OR 28.81 (95% CI 21.79 to 38.08)), followed by liver cancer (OR 18.38 (95% CI 12.56 to 26.89)). There was no significant association between NASH and risk for depression (OR 1.11 (95% CI 0.87 to 1.41)), insomnia (OR 1.12 (95% CI 0.94 to 1.34)) or chronic kidney diseases (OR 0.81 (95% CI 0.58 to 1.12)). ConclusionsIn the daily medical care of patients, it is necessary to consider sex and age differences and to pay close attention to the risk of liver cancer, as well as other lifestyle-related comorbidities associated with NASH.