Hospital-Acquired Acute Kidney Injury in Older Patients: Clinical Characteristics and Drug Analysis

<b><i>Background:</i></b> Information on older patients with hospital-acquired acute kidney injury (HA-AKI) and use of drugs is limited. <b><i>Aim:</i></b> This study aimed to assess the clinical characteristics, drug uses, and in-hospital outcomes of hospitalized older patients with HA-AKI. <b><i>Methods:</i></b> Patients aged ≥65 years who were hospitalized in medical wards were retrospectively analyzed. The study patients were divided into the HA-AKI and non-AKI groups based on the changes in serum creatinine. Disease incidence, risk factors, drug uses, and in-hospital outcomes were compared between the groups. <b><i>Results:</i></b> Of 26,710 older patients in medical wards, 4,491 (16.8%) developed HA-AKI. Older patients with HA-AKI had higher rates of multiple comorbidities and Charlson Comorbidity Index score than those without AKI (<i>p</i> &#x3c; 0.001). In the HA-AKI group, the proportion of patients with prior use of drugs with possible nephrotoxicity was higher than that of patients with prior use of drugs with identified nephrotoxicity (<i>p</i> &#x3c; 0.05). The proportions of patients with critical illness, use of nephrotoxic drugs, and the requirements of intensive care unit treatment, cardiopulmonary resuscitation, and dialysis as well as in-hospital mortality and hospitalization duration and costs were higher in the HA-AKI than the non-AKI group; these increased with HA-AKI severity (all <i>p</i> for trend &#x3c;0.001). With the increase in the number of patients with continued use of drugs with possible nephrotoxicity after HA-AKI, the clinical outcomes showed a tendency to worsen (<i>p</i> &#x3c; 0.001). Moreover, HA-AKI incidence (adjusted odds ratio [OR], 10.26; 95% confidence interval (CI), 8.27–12.74; <i>p</i> &#x3c; 0.001), and nephrotoxic drugs exposure (adjusted OR, 1.76; 95% CI, 1.63–1.91; <i>p</i> &#x3c; 0.001) had an association with an increased in-hospital mortality risk. <b><i>Conclusion:</i></b> AKI incidence was high among hospitalized older patients. Older patients with HA-AKI had worse in-hospital outcomes and higher resource utilization. Nephrotoxic drug exposure and HA-AKI incidence were associated with an increased in-hospital mortality risk.