Long-Term Outcomes After Acute Kidney Injury During Hospitalization: A Systematic Review and Meta-Analysis of Matched Controls Studies

Objectives: The impact of acute kidney injury (AKI) on long-term outcomes of hospital survivors is controversial. We conducted a systematic review and meta-analysis of all studies reporting such outcomes in patients with AKI and including a control population. Data Sources: We included original studies published in peer-reviewed journals that compared long-term outcomes (survival, need for dialysis, chronic kidney disease [CKD]) among hospitalized patients with vs. without AKI. Study Selection: Pertinent articles enrolled patients who experienced and survived a defined episode of AKI, included a control group without AKI, and reported at least one long-term outcome (mortality, dialysis, or CKD), with a minimum follow-up of 1 year. Data Extraction: Two independent investigators extracted data on study characteristics, patient populations, follow-up duration, and long-term outcomes. Discrepancies were resolved by consensus. Data Synthesis: We identified 14 studies for a total of 1,058,109 overall matched patients with a median duration of follow-up of 3 years. Patients who experienced an episode of AKI and survived hospital discharge had a significant increase in long-term mortality at the longest follow-up available for each study (137,506/519,672 [26.4%] vs. 93,702/530,663 [17.6%]; relative risk [RR], 1.42; 95% CI, 1.13–1.78; p = 0.002), compared with controls. They also had a greater risk of receiving dialysis (1,928/42,529 [4.5%] vs. 854/42,529 [2.0%]; RR, 2.48; 95% CI, 1.79–3.43; p < 0.001), and of developing CKD (2,956/5,739 [51.5%] vs. 2,902/7,781 [37.3%]; RR, 1.71; 95% CI, 1.33–2.19; p < 0.001). Conclusions: Compared with controls, patients who experienced an episode of AKI and survived to hospital discharge have an increased risk of death, dialysis, and CKD.