Kidney Outcomes After Contrast Exposure in Patients Recovering From Dialysis-Requiring Acute Kidney Injury: A Target Trial Emulation Study.

RATIONALE &

OBJECTIVE

The impact of iodinated contrast media (ICM) on kidney outcomes remains debated, especially when used with patients recovering from acute kidney injury requiring dialysis (AKI-D). Despite apparent clinical recovery, these individuals may remain vulnerable to repeat kidney insults.

STUDY

DESIGN

Retrospective cohort study.

SETTING &

PARTICIPANTS

Adults recovering from AKI-D were identified using Taiwan's National Health Insurance Research Database between January 2015 and December 2022.

EXPOSURE: Intravenous ICM.

OUTCOME: The primary kidney event was recurrent treatment with dialysis; the secondary was persistent kidney dysfunction, defined as at least 0.3 mg/dL or 50% increase in serum creatinine from post-AKI recovery levels at 1 year after index date.

ANALYTICAL APPROACH: Observational analysis using inverse probability of treatment weighting (IPTW) within a target trial emulation framework to compare patients exposed to ICM with unexposed counterparts.

RESULTS

Among 23,263 patients recovering from dialysis after AKI-D (mean age, 69.6 years; 58.5% men), 1,551 (6.7%) received contrast-enhanced computed tomography in the first 30 days. After IPTW, ICM was independently associated with a higher hazard of recurrent treatment with dialysis (subdistribution hazard ratio (SHR), 1.37 [95% CI, 1.20-1.56]) and persistent kidney dysfunction (SHR, 1.11 [95% CI, 1.01-1.23]). Generalized-additive modeling showed that the risk for kidney events was greatest when the estimated glomerular filtration rate (eGFR) after AKI-D fell below 36 mL/min/1.73 m2 in the patients who received contrast, compared with 22.8 mL/min/1.73 m2 in patients who did not. External validation in an independent, multihospital cohort of 1,195 AKI-D survivors confirmed the excess risk of kidney events after contrast exposure.

LIMITATIONS: The observational nature of this study precludes definitive causal inference.

CONCLUSIONS

Among adults recently recovering from AKI-D and no longer dependent on dialysis, ICM exposure was associated with an increased risk of a recurrent treatment with dialysis and persistent kidney dysfunction. These findings inform clinical management of these patients and the use of contrast in this high-risk population.

PLAIN-LANGUAGE SUMMARY: The effects of iodinated contrast on kidney function remain controversial and are even less well understood in patients recovering from acute kidney injury requiring dialysis (AKI-D). In this nationwide observational study using a target trial emulation framework, we evaluated adults with AKI-D whose recovery permitted discontinued dialysis. We found that patients who underwent contrast-enhanced computed tomography scans within 30 days of dialysis cessation were more likely to require dialysis again and to develop persistent kidney dysfunction compared with those who did not receive contrast. These findings suggest that kidney function may remain vulnerable after apparent recovery and support careful consideration of contrast use in this high-risk population.