Variation in implementation of pericontrast prophylaxis during CT pulmonary angiography

Objectives: Contrast-associated acute kidney injury (CA-AKI) remains a concern after computed tomography pulmonary angiography (CTPA), yet the benefit of prophylaxis outside clearly high-risk patients is uncertain and real-world practice is poorly characterized. We examined prophylaxis use and type across baseline estimated glomerular filtration rate (eGFR) categories, characteristics associated with prophylaxis receipt, and CA-AKI frequency under three operational definitions. Methods: In a single-center cohort of 897 CTPA encounters among 846 adults between 2014 and 2018 with post-contrast creatinine monitoring, we described prophylaxis receipt and type across baseline eGFR categories, evaluated factors associated with receipt using Firth-penalized logistic regression, and assessed CA-AKI frequency using traditional, European Society of Urogenital Radiology criteria (ESUR), and modified Kidney disease: Improving global outcomes criteria (KDIGO) creatinine-based definitions applied to the 48–72-h creatinine. Results: Prophylaxis was received in 270/897 encounters (30.1%), rising with lower baseline eGFR (from 26.1% at ≥60 to 81.0% at <30 mL/min/1.73 m 2 ). At the extremes of risk, 4/21 encounters (19.0%) with eGFR <30 received no prophylaxis, whereas 206/789 (26.1%) with eGFR ≥60 received prophylaxis. Receipt was independently associated with lower eGFR (adjusted odds ratio 3.70, 95% confidence interval 2.26–6.06 for 30–59; 12.0, 3.94– 36.3 for <30), inpatient status (3.97, 1.41–11.15), male sex (1.63, 1.20–2.20), and diuretic use (1.57, 1.01–2.44). Normal saline alone was the most common classifiable regimen (195/270; 72.2%). CA-AKI frequency was 13.0% (traditional) and 8.2% (ESUR and KDIGO) and did not differ significantly by prophylaxis status under any definition. The ESUR and KDIGO definitions coincided in this cohort; this coincidence was specific to these data and may not hold in other populations. Conclusion: Prophylaxis use generally followed baseline eGFR but varied at the highest and lowest renal-risk strata. This variation, rather than overall prophylaxis rates, constitutes the central finding and may support more standardized risk-assessment pathways. CA-AKI frequency varied across operational definitions, and the predominantly inpatient cohort limits generalizability to outpatient CTPA practice.