Risk Factors with 30-Day Readmission and the Impact of Length of Hospital Stay on It in Patients with Heart Failure: A Retrospective Observational Study Using a Japanese National Database.

Heart failure is a major disease, and its 30-day readmission (readmission within 30-day after discharge) negatively impacts patients and society. Thus, we need to stratify the risk and prevent readmission. We aimed to investigate risk factors associated with 30-day readmission and examine the impact of length of hospital stay (LOS) on 30-day readmission. Using the Diagnosis-Procedure-Combination database from April 2018 to March 2021, we conducted multiple logistic regression to investigate risk factors with 30-day readmission. Also, we conducted subgroup analysis in the short LOS group. To examine the association between LOS and 30-day readmission, we performed propensity score matching between the short and middle LOS groups. As a result, we categorized 10,283 patients and 169,842 patients into the readmission group and the no-readmission group. We identified the following factors as the risk of readmission: short LOS, female, smoking, older age, lower body mass index, lower barthel index, artificial ventilator, beta-blockers, thiazides, tolvaptan, loop diuretics, carperitides, class Ⅲ antiarrhythmic agents, myocardial infarction, diabetes, renal disease, atrial fibrillation, dilated cardiomyopathy, and discharge to home. As a subgroup analysis in the short LOS group, we revealed that the short LOS group risk factors differed from overall. After propensity score matching in the short LOS group and middle LOS group, 37,199 pairs were matched, and we revealed that shorter LOS increases the risk of readmission. These results demonstrated that shortened LOS increases 30-day readmission, and risk factors are unique to each LOS. We suggest stratifying the readmission risk and being careful with early discharge.