Introduction . Detecting acute kidney injury (AKI) in the first days of hospitalization could prevent potentially fatal complications. However, epidemiological data are scarce, especially on nonsurgical patients. Objectives . To determine the incidence and risk factors associated with AKI within five days of hospitalization (EAKI). Methods . Prospective cohort of patients hospitalized in the Internal Medicine Department. Results . A total of 16% of 400 patients developed EAKI. The associated risk factors were prehospital treatment with nephrotoxic drugs (2.21 OR; 95% CI 1.12–4.36,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn fontstyle="italic">0.022</mml:mn></mml:math>), chronic kidney disease (CKD) in stages 3 to 5 (3.56 OR; 95% CI 1.55–8.18,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn fontstyle="italic">0.003</mml:mn></mml:math>), and venous thromboembolism (VTE) at admission (5.05 OR; 95% CI 1.59–16.0,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn fontstyle="italic">0.006</mml:mn></mml:math>). The median length of hospital stay was higher among patients who developed EAKI (8 [IQR 5–14] versus 6 [IQR 4–10],<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn fontstyle="italic">0.008</mml:mn></mml:math>) and was associated with an increased requirement for dialysis (4.87 OR 95% CI 2.54 to 8.97,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn fontstyle="italic">0.001</mml:mn></mml:math>) and in-hospital death (3.45 OR; 95% CI 2.18 to 5.48,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn fontstyle="italic">0.001</mml:mn></mml:math>). Conclusions . The incidence of EAKI in nonsurgical patients is similar to the worldwide incidence of AKI. The risk factors included CKD from stage 3 onwards, prehospital treatment with nephrotoxic drugs, and VTE at admission. EAKI is associated with prolonged hospital stay, increased mortality rate, and dialysis requirement.
