Estimating the Prevalence of Transthyretin Amyloid Cardiomyopathy in a Large In-Hospital Database in Japan

Introduction: Transthyretin amyloid cardiomyopathy (ATTR-CM)-a debilitating, fatal disease resulting from the deposition of transthyretin (TTR) amyloid fibrils-can be hereditary due to mutations in the TTR gene (ATTRm) or wild type (ATTRwt). The global prevalence of ATTR-CM is largely unknown, although likely underestimated, with no formal epidemiological prevalence studies in Japan. This study aimed to estimate the prevalence of ATTR-CM in a large in-hospital database in Japan. Methods: This was a retrospective, observational, cross-sectional study which utilized data from all adult patients (aged >= 20 years) in the hospital-based Japan Medical Data Vision (MDV) database from January 2010 to September 2018 to estimate the number of currently diagnosed ATTR-CM patients and describe their demographic and clinical characteristics and diagnostic modalities. ATTR-CM patients (ATTRwt and ATTRm) were identified using a range of diagnosis codes that were applied to create broad and narrow definitions of the disease. Results: Over the 9 years of this study, there were 3255 (155.8 per million adult patients in the MDV database) to 3992 (191.1 per million) diagnoses of ATTRwt and 67 (3.2 per million) to 106 (5.1 per million) diagnoses of ATTRm in the MDV database (based on the narrow and broad definitions, respectively). There were 444 (21.2 per million) diagnoses of amyloid light-chain (AL) amyloidosis. Considering only those patients who were also diagnosed with heart failure, there were 1468 (70.3 per million) to 1798 (86.1 per million) diagnoses of ATTRwt and 50 (2.4 per million) to 61 (2.9 per million) diagnoses of ATTRm. Most ATTRwt patients (similar to 90%) did not have a record of endomyocardial or abdominal wall biopsy, or of scintigram. Conclusion: This retrospective study provides an estimate of the number of patients diagnosed with ATTR-CM in a large in-hospital database in Japan over a period of 9 years. Improving awareness of disease prevalence may improve diagnosis and treatment.