Characteristics and short-term outcomes of outpatient and inpatient cardiac catheterizations: A descriptive study using a nationwide claim database in Japan.

Background: Most previous studies on outpatient cardiac catheterization have been conducted in Western countries, but Japanese studies are rare. We aimed to describe patient characteristics and short-term clinical outcomes of outpatient cardiac catheterization compared to those of inpatient cardiac catheterization in Japan.
Methods: We conducted a retrospective cohort study using data from the JMDC Claims Database. We identified all adult patients aged ≥18 years who underwent cardiac catheterization between April 2012 and October 2021. We investigated patient characteristics and clinical outcomes (i.e. all-cause mortality, stroke, acute kidney injury, bleeding, vascular complications, percutaneous coronary intervention, and total healthcare costs) within 2, 7, and 30 days between patients who underwent outpatient cardiac catheterization (outpatient group) and those who underwent inpatient cardiac catheterization (inpatient group).
Results: Of the 37,002 eligible patients (57.6 % <60 years old, and 80.2 % male), 1853 (5.01 %) underwent outpatient cardiac catheterization. The outpatient group was more likely to be male, have more comorbidities, and be performed at non-university hospitals than the inpatient group. The proportion of patients who underwent right heart catheterization and imaging was lower in the outpatient group. There were no significant differences in 7-day major complications between the two groups (all-cause mortality, 0.0 % versus 0.0 %, p = 0.57; acute kidney injury, 0.0 % versus 0.1 %, p = 0.10, bleeding, 0.5 % versus 0.9 %, p = 0.052; vascular complication, 0.0 % versus 0.1 %, p = 0.23, respectively). The 30-day total healthcare costs were lower in the outpatient group than in the inpatient group (mean 3212 US dollars versus 3955 US dollars, p = 0.003).
Conclusions: Approximately 5 % of cardiac catheterizations were performed in an outpatient setting. Given the low adverse event risk observed in this study, it may be a reasonable option to widen outpatient cardiac catheterization to include potential populations in Japan, warranting further studies.
Competing Interests: Declaration of competing interest Nao Setogawa is an employee of Terumo Corporation. All other authors have reported that they have no relationships relevant to the contents of this paper.
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