Supplementary Material for: Acute Pericarditis-Associated Hospitalization in the USA: A Nationwide Analysis, 2003-2012

<b><i>Background and Objectives:</i></b> Epidemiologic data on hospitalizations for acute pericarditis are scarce. We sought to study the trends in these hospitalizations and outcomes in the USA over a 10-year period. <b><i>Methods:</i></b> We used the 2003-2012 Nationwide Inpatient Sample database to identify admissions with a primary diagnosis of acute pericarditis. Outcomes included hospitalization rate, case fatality rate (CFR), length of stay (LOS), hospital charges, complications and diagnostic and therapeutic procedures. <b><i>Results:</i></b> We observed an estimated 135,710 hospitalizations for acute pericarditis among patients ≥16 years during the study period (mean age 53.5 ± 18.5 years; 40.5% women). The incidence of acute pericarditis hospitalizations was significantly higher for men than for women [incidence rate ratio (IRR) 1.56; 95% confidence interval (CI) 1.54-1.58; p &lt; 0.001]; it decreased from 66 to 54 per million person-years (p &lt; 0.001). CFR and LOS declined significantly during the study period (CFR: 2.2% in 2003 to 1.4% in 2012; LOS: 4.8 days in 2003 to 4.1 days in 2012; p &lt; 0.001 for both). The average inflation-adjusted health-care charge increased from USD 31,242 to 38,947 (p &lt; 0.001). <b><i>Conclusion:</i></b> The hospitalization rate, CFR and LOS associated with acute pericarditis have declined significantly in the US population. Average charges for acute pericarditis hospitalization have increased.

**背景与研究目标**：目前关于急性心包炎住院病例的流行病学数据较为匮乏。本研究旨在针对美国十年间的急性心包炎住院情况及其转归趋势展开分析。
**研究方法**：本研究采用2003-2012年全国住院患者样本（Nationwide Inpatient Sample）数据库，筛选以急性心包炎为主要诊断的住院病例。本次研究的转归指标包括住院率、病死率（case fatality rate, CFR）、住院时长（length of stay, LOS）、住院费用、并发症以及诊断与治疗操作。
**研究结果**：本研究期间，共纳入≥16岁的急性心包炎住院患者约135710例，患者平均年龄为53.5±18.5岁，女性占比40.5%。男性急性心包炎住院发生率显著高于女性[发病比率（incidence rate ratio, IRR）=1.56；95%置信区间（confidence interval, CI）=1.54~1.58；p<0.001]；该发生率从每百万人年66例降至54例（p<0.001）。研究期间，患者的病死率（CFR）与住院时长（LOS）均显著下降：2003年CFR为2.2%，2012年降至1.4%；2003年LOS为4.8天，2012年降至4.1天，两项指标的统计学差异均为p<0.001。经通胀调整后的平均医疗费用从31242美元升至38947美元（p<0.001）。
**研究结论**：美国人群中急性心包炎相关的住院率、病死率（CFR）与住院时长（LOS）均显著下降，而急性心包炎住院的平均医疗费用则有所上升。