Acute Kidney Injury in Adults Exposed to Commonly Used Nephrotoxic Medications and Iodinated Contrast: Frequency, Associated Factors, and Early Outcomes.

Background Acute kidney injury (AKI) in hospitalized adults is often framed as an unavoidable consequence of critical illness. Yet a substantial proportion emerges within a modifiable clinical space: exposure to nephrotoxic medications, iodinated contrast, hemodynamic stress, and delayed renal monitoring. This study evaluated whether high nephrotoxic exposure was associated with in-hospital AKI among adult inpatients after balancing measured baseline risk. Methods This prospective observational cohort study included adult inpatients admitted to general wards and intensive care units at Mamata Medical College and General Hospital, Khammam, India. From 1,500 admissions, 240 patients with high nephrotoxic medication exposure and/or iodinated contrast exposure were identified and matched 1:1 with 240 unexposed controls using propensity-score matching. Matching variables included age, sex, body mass index, diabetes mellitus, congestive heart failure, baseline serum creatinine, estimated glomerular filtration rate, blood urea nitrogen, and intensive care unit status. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria, primarily using serum creatinine changes. A sensitivity analysis excluded very mild Stage 1a AKI. The primary outcome was in-hospital AKI after the index date; secondary outcomes included AKI severity, Stages 2-3 AKI, time to AKI among AKI cases, in-hospital mortality, length of stay, vancomycin concentration patterns, and medication-specific AKI-overlapping exposure burden. Results After matching, baseline characteristics were generally balanced, although blood urea nitrogen remained modestly imbalanced. AKI occurred in 61 exposed patients and 38 controls, corresponding to 25.4% versus 15.8% and an odds ratio of 1.81 (95% CI, 1.15-2.85; p = 0.013). Severe AKI was numerically higher in exposed patients but did not reach statistical significance. After excluding Stage 1a AKI, clinically meaningful AKI remained more frequent in the exposed group, 17.5% versus 10.0% (OR, 1.91; 95% CI, 1.12-3.27; p = 0.024). Vancomycin, iodinated contrast, piperacillin-tazobactam, antivirals, and calcineurin/mammalian target of rapamycin (mTOR) inhibitors contributed prominently to AKI-overlapping exposure days. Maximum vancomycin concentrations were higher among patients who developed AKI, although reverse causality could not be excluded. Conclusion High nephrotoxic medication and/or iodinated contrast exposure was associated with a higher frequency of in-hospital AKI in matched adult inpatients. The association persisted after excluding minor creatinine-only events, supporting a clinically meaningful renal injury signal. These findings strengthen the need for nephrotoxin stewardship, early creatinine surveillance, dose adjustment, hydration optimization, and active multidisciplinary review when renal-risk medications are clinically unavoidable.