Supplementary Material for: Incidence of Serum Creatinine Monitoring and Outpatient Visit Follow-Up among Acute Kidney Injury Survivors after Discharge: A Population-Based Cohort Study

<b><i>Introduction:</i></b> Acute kidney injury (AKI) affects 20% of hospitalized patients and worsens outcomes. To limit complications, post-discharge follow-up and kidney function testing are advised. The objective of this study was to evaluate the frequency of follow-up after discharge among AKI survivors. <b><i>Methods:</i></b> This was a population-based cohort study of adult Olmsted County residents hospitalized with an episode of stage II or III AKI between 2006 and 2014. Those dismissed from the hospital on dialysis, hospice, or who died within 30 days after discharge were excluded. The frequency and predictors of follow-up, defined as an outpatient serum creatinine (SCr) level or an in-person healthcare visit after discharge were described. <b><i>Results:</i></b> In the 627 included AKI survivors, the 30-day cumulative incidence of a follow-up outpatient SCr was 80% (95% confidence interval [CI]: 76% and 83%), a healthcare visit was 82% (95% CI: 79 and 85%), or both was 70% (95% CI: 66 and 73%). At 90 days and 1 year after discharge, the cumulative incidences of meeting both follow-up criteria rose to 82 and 91%, respectively. Independent predictors of receiving both an outpatient SCr assessment and healthcare visit within 30 days included lower estimated glomerular filtration rate at discharge, higher comorbidity burden, longer length of hospitalization, and greater maximum AKI severity. Age, sex, race/ethnicity, education level, and socioeconomic status did not predict follow-up. <b><i>Conclusions:</i></b> Among patients with moderate to severe AKI, 30% did not have follow-up with a SCr and healthcare visit in the 30-day post-discharge interval. Follow-up was associated with higher acuity of illness rather than demographic or socioeconomic factors.

**引言：** 急性肾损伤（Acute kidney injury, AKI）累及20%的住院患者，且会恶化患者预后。为减少并发症发生，临床推荐对患者实施出院后随访及肾功能检测。本研究旨在评估急性肾损伤幸存者出院后的随访频率。
**研究方法：** 本研究为基于人群的队列研究，纳入2006年至2014年间于奥尔姆斯特德县住院的成年居民，其住院期间曾发生II期或III期急性肾损伤。排除标准包括：出院时仍维持透析、接受临终关怀，或出院后30天内死亡者。本研究描述了随访的发生频率及其影响因素，随访定义为出院后门诊血清肌酐（serum creatinine, SCr）检测或面对面就医行为。
**研究结果：** 本研究共纳入627名急性肾损伤幸存者。出院后30天内，仅完成门诊血清肌酐检测的随访累积发生率为80%（95%置信区间[CI]：76%~83%），仅完成面对面就医的随访累积发生率为82%（95%CI：79%~85%），两项均完成的随访累积发生率为70%（95%CI：66%~73%）。至出院后90天及1年时，两项随访指标均达标的累积发生率分别升至82%与91%。出院后30天内同时完成门诊血清肌酐检测与面对面就医的独立影响因素包括：出院时估算肾小球滤过率更低、合并症负荷更高、住院时长更长，以及急性肾损伤最大严重程度更高。年龄、性别、种族/族裔、教育水平及社会经济地位均未对随访行为产生预测作用。
**结论：** 对于中至重度急性肾损伤患者，有30%在出院后30天内未完成血清肌酐检测与就医随访。随访行为与疾病危重程度更高相关，而非人口学或社会经济因素。