A conservative screening approach to kidney disease before contrast-enhanced computed tomography in outpatient population

A. Fathala, S. Almehemeid, I. Alkharji, R. Alrwais, R. Benkuddah, J. Aljahani

Radiology, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. ahm35799@hotmail.com

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• Radiology

OBJECTIVE: To determine the incidence of abnormal renal function in an outpatient population referred for contrast-enhanced computed tomography (CECT) and assess the risk factors that could be used to eliminate superfluous estimated glomerular filtration rate (eGFR) testing.

PATIENTS AND METHODS: The following risk factors were assessed in random patients referred for outpatient CECT: age >60 years, diabetes mellitus, hypertension, anemia, congestive heart failure, and a history of kidney/urological disease or renal surgery. The patients’ serum creatinine and eGFR levels, gender, and the type of CECT were recorded.

RESULTS: The study included 500 patients (mean age 50±16 years). Among them, 36 (7.2%) patients had an eGFR <60 ml/min/1.73 m2 of which 31 (6.2%) had an eGFR of 59-45 ml/min/1.73 m2 and 5 (1%) patients an eGFR <45 ml/min/1.73 m2. No patients had an eGFR <30 ml/min/1.73 m2. There was a statistically significant association between an abnormal eGFR and age >60 years, diabetes mellitus, hypertension, and chronic kidney disease (p<0.05). By selecting only, the patients with one of the identified risk factors for eGFR assessment before CECT, all the patients with an abnormal eGFR (<60 ml/min/1.73 m2) were detected with sensitivity and a negative predictive value of 100%.

CONCLUSIONS: Patients with an abnormal eGFR can be detected with sensitivity and a negative predictive value of 100% using our screening approach before CECT, and superfluous eGFR testing can thus be reduced by approximately 50% with concomitant cost savings. Outpatients without any risk factors should be excluded from routine renal function assessment before CECT.

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