Supplementary Material for: Burden of acute kidney injury among adult hospital patients in the Italian Lombardy Region – a 20 years real world data analysis

Background: Acute kidney injury (AKI) is a frequent condition, with persisted shortage of large-scale epidemiological studies. We analyzed the population-wide healthcare system of the Italian Lombardy region over the 2000-2019 period, and evaluated AKI incidence, mortality, and related healthcare resources utilization and cost in all citizens 40 years and older.
Methods: The retrospective cohort analysis of an administrative claims database that routinely collects information about health care provision in a high-income region with 10 million citizens. Over 20 years, AKI was identified in 84,384 hospital discharge records by the International Classification of Diseases 9th Revision codes (mean age 77.4±11.6 years, 52.5% were males).
Results: From 2000 to 2019, the AKI rates per 100,000 population changed from 32.9 to 90.5 for incidence, from 4.7 to 11.9 for mortality, and from 32.3 to 44.1 for years of life lost (YLLs), respectively. In-hospital mortality changed slightly (14.2% and 13.2%, respectively), while 30-day mortality decreased from 21.5% to 17.4%, respectively. Incidence rates increased with age and were higher in males, and varied almost four-fold between provinces. The median hospitalization cost was €4,014 (IQR 3,652; 4,134), and the annual cost of treatment risen from €5.2 million in 2000 to €22.9 million in 2019. Hemodialysis was administered in 7.4% of hospitalizations. Over the total study period the cumulative AKI burden accounted for 11,420 in-hospital deaths, 63,370.8 YLLs, and €329 million of direct cost.
Conclusions: This real-world analysis demonstrates the high burden of AKI with prominent geographical differences that require further implementation of preventive and diagnostic actions.

背景：急性肾损伤（Acute kidney injury, AKI）是一种常见临床综合征，目前大规模流行病学研究仍存在显著缺口。本研究针对2000年至2019年意大利伦巴第大区的全民医疗保健系统开展分析，评估了40岁及以上全体公民的AKI发病率、死亡率、相关医疗资源利用情况及治疗成本。
方法：本研究为回顾性队列分析，所用数据来自覆盖1000万人口的高收入地区的常规医疗服务信息行政索赔数据库。在20年研究周期内，研究人员通过国际疾病分类第9版（International Classification of Diseases 9th Revision, ICD-9）编码，从84384份出院记录中识别出AKI病例，患者平均年龄为77.4±11.6岁，男性占比52.5%。
结果：2000年至2019年，每10万人口的AKI发病率从32.9升至90.5，死亡率从4.7升至11.9，寿命损失年（Years of Life Lost, YLLs）从32.3升至44.1。住院死亡率变化幅度较小（分别为14.2%和13.2%），而30天死亡率从21.5%降至17.4%。发病率随年龄增长而升高，且男性群体发病率更高，各省之间的发病率差异可达近4倍。住院费用中位数为4014欧元（四分位距：3652；4134），年度治疗总成本从2000年的520万欧元升至2019年的2290万欧元。7.4%的住院患者接受了血液透析。在整个研究周期内，AKI累计造成11420例院内死亡、63370.8个寿命损失年，以及3.29亿欧元的直接医疗成本。
结论：此项真实世界研究分析显示，AKI疾病负担沉重，且存在显著地域差异，亟需进一步强化预防与诊断相关工作的落地实施。