Predicting contrast-induced nephropathy after CT pulmonary angiography in the critically ill: a retrospective cohort study

Kwok M Ho,Yusrah Harahsheh

doi:10.1186/s40560-018-0274-z

Abstract

BackgroundIt is uncertain whether we can predict contrast-induced nephropathy (CIN) after CT pulmonary angiography (CTPA). This study compared the ability of a validated CIN prediction score with the Pulmonary Embolism Severity Index (PESI) in predicting CIN after CTPA.MethodsThis cohort study involved critically ill adult patients who required a CTPA to exclude acute pulmonary embolism (PE). Patients with end-stage renal failure requiring dialysis were excluded. CIN was defined as an elevation in plasma creatinine concentrations > 44.2μmol/l (or 0.5 mg/dl) within 48 h after CTPA.ResultsOf the 137 patients included, 77 (51%) were hypotensive, 54 (39%) required inotropic support, and 68 (50%) were mechanically ventilated prior to the CTPA. Acute PE was confirmed in 21 patients (15%) with 14 (10%) being bilateral. CIN occurred in 56 patients (41%) with 35 (26%) required dialysis subsequent to CTPA. The CIN prediction score had a good ability to discriminate between patients with and without developing CIN (Area under the receiver-operating-characteristic (AUROC) curve 0.864, 95% confidence interval [CI] 0.795–0.916) and requiring subsequent dialysis (AUROC 0.897, 95% CI 0.833–0.942) and was better than the PESI in predicting both outcomes (AUROC 0.731, 95% CI 0.649–0.804 and 0.775, 95% CI 0.696–0.842, respectively). A CIN risk score > 10 and 12 had an 82.1 and 85.7% sensitivity and 81.5 and 78.4% specificity to predict subsequent CIN and dialysis, respectively. The CIN prediction model tended to underestimate the observed risks of dialysis, but this was improved after recalibrating the slope and intercept of the original prediction equation.ConclusionsThe CIN prediction score had a good ability to discriminate between critically ill patients with and without developing CIN after CTPA. Used together for critically ill patients with suspected acute PE, the CIN prediction score and PESI may be useful to inform clinicians when the benefits of a CTPA scan will outweigh its potential harms.

Highlights

It is uncertain whether we can predict contrast-induced nephropathy (CIN) after CT pulmonary angiography (CTPA)
Characteristics of the study patients Of the 141 patients who required a CTPA to exclude acute pulmonary embolism (PE) during the study period, 137 patients who did not have end-stage renal failure were included for further analysis
The characteristics and outcomes of the study cohort are described in detail in Table 1, and no patients had missing data on the risk factors needed to estimate the CIN prediction score and Pulmonary Embolism Severity Index (PESI), occurrence of CIN, and requirement for dialysis

Summary

Introduction

It is uncertain whether we can predict contrast-induced nephropathy (CIN) after CT pulmonary angiography (CTPA). In addition to a small risk of anaphylaxis, use of radiocontrast can induce acute kidney injury or contrast-induced nephropathy (CIN), especially in patients with pre-existing renal impairment. While most patients who develop CIN will not require dialysis and will recover without permanent complications, there is an increasing evidence to suggest that CIN can induce longterm renal damage and mortality in high-risk patients. In the study by Mehran et al, the risks of requiring dialysis for CIN and 1-year mortality were 13 and 33% for those with multiple risk factors for CIN compared to only < 0.5 and 2% for those with the lowest risk of developing CIN, respectively [10]. The clinical significance of CIN was further confirmed by a recent study which showed that nearly one third of the inhospital mortality after percutaneous coronary intervention was attributable to CIN, and one death could be potentially prevented by preventing nine cases of CIN [11]

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