INCIDENCE OF CONTRAST INDUCED NEPHROPATHY IN PATIENTS UNDERGOING CONTRAST ENHANCED COMPUTED TOMOGRAPHY AND ITS CORRELATION WITH SERUM CYSTATIN C AT 48 HOURS

Introduction:

Iodinated radiographic contrast media computerized tomography (CT) studies are used for both diagnostic and therapeutic procedures. Contrast media are associated with a spectrum of adverse reactions, major concern being contrast induced acute kidney injury (AKI).

Contrast induced nephropathy (CIN) frequently complicates critical illness and results in high short-term morbidity, mortality, need for dialysis, prolonged hospitalization and long-term adverse events in the form of chronic kidney disease. 

Serum creatinine and urine output are late markers of AKI. Evidence has built up regarding their drawbacks and novel biomarkers for kidney function are being searched. Serum Cystatin C (SCys C) is one such marker. Its concentration is independent of age, sex, muscle mass and nutritional status. 

 Apart from finding out the risk of CIN, this study also explored the role of use of SCys C as a novel biomarker in early diagnosis of CIN. 

Methods:

This was a prospective observational hospital-based study involving 150 eligible patients who underwent contrast enhanced computed tomography (CECT) spanning 18 months. Patients with hypersensitivity to contrast media, baseline eGFR<30 ml/min/1.73m2, AKI ascribable to other causes and pregnancy were excluded. The study was carried out after institutional ethics committee approval. 

 CIN- serum creatinine (CIN- SCr): was diagnosed as per AKI criteria as defined by KDIGO. 

CIN-serum cystatin C (CIN- SCys C) was defined as rise in serum cystatin C ≥ 15 % from baseline in 48 hours. 

Results:

• A total of 150 patients undergoing CECT were enrolled in our study. Mean age of the population was 45.01 ± 15.55 years. 114 (76%) were male and 36 (24%) were females. 

• 104, 38 and 8 participants were of CKD stage 1/2/3 respectively. 

• 51 (34%) had comorbidities of which 16.7 % were diabetic & 10 % were hypertensive. 

• At 48 hours, 

       i) The incidence of CIN- SCr as per KDIGO criteria in our study was 11/150 (7.3 %); all had stage 1 AKI. 

       ii) The incidence of CIN- SCys C criteria was 23/150 (15.3%). In an additional 12 (8%) participants AKI were picked up early using SCys C. 

• Serum cystatin C had a sensitivity of 100% and specificity of 91% in detecting CIN- SCr. It had a positive predictive value (PPV) of 48% and negative predictive value (NPV) of 100%. Overall diagnostic accuracy of serum cystatin C was found to be 92%. 

• Diabetes (p<0.001), hypertension (p= 0.002), proteinuria (p=0.002) and age (p=0.03) were all significantly associated with the risk of developing CIN. 

• There was an increasing trend of CIN- SCys C incidence as eGFR declined, however it was not statistically significant (p= 0.723). 

• There was no association between CIN and contrast volume, dose, haemoglobin, gender, smoking, alcohol consumption and body weight. 

• Receiver operating characteristic (ROC) curve analysis was done and a serum cystatin C baseline cut off level of ≥1.047 mg/l was found to predict CIN- SCr with a sensitivity of 64%, specificity of 81%, PPV of 20.6% and NPV of 96.6 %. 

Conclusions:

• Incidence of CIN- SCr was 7.3%. 

• Incidence of CIN- SCys C was 15.3%. 

• SCys C was found to be significantly more sensitive marker for CIN as compared to serum creatinine. 

• CIN incidence was significantly associated with higher age, diabetes mellitus, hypertension, proteinuria. 

• Serum cystatin C baseline cut off level of ≥1.047 mg/l was predictive of CIN. 

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.