Screening for impaired renal function in outpatients before iodinated contrast injection: Comparing the Choyke questionnaire with a rapid point-of-care-test.
OBJECTIVE
To determine the usefulness of the Choyke questionnaire with a creatinine point-of-care test (POCT) to detect impaired renal function amongst outpatients receiving intravenous iodinated contrast in a tertiary centre.


METHODS
Between July and December 2012, 1361 outpatients had their serum creatinine determined by POCT and answered the Chokye questionnaire just before their examination.


RESULTS
Four hundred and eighty (35.2%) patients had at least one 'Yes' response. Forty-four patients (3.2%) had estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2) and 14 patients (1.0%) have eGFR <45 mL/min/1.73 m(2). Sensitivity, specificity, positive predictive value and negative predictive value of the Choyke criteria in detecting patients with eGFR <60 mL/min/1.73 m(2) are respectively: 65.9%, 65.8%, 6.0% and 98.3% and to detect eGFR <45 mL/min/1.73 m(2): 92.9%, 65.3%, 2.7% and 99.9%. Only 'Yes' responses to 'Have you ever been told you have renal problems?' and 'Do you have diabetes mellitus?' were statistically significant in predicting eGFR <45 mL/min/1.73 m(2), with odds ratio 98.7 and 4.4 respectively.


CONCLUSIONS
The Choyke questionnaire has excellent sensitivity and moderate-to-good specificity in detecting patients with <45 mL/min/1.73 m(2), below this level it has been shown that risk of contrast induced nephropathy increases significantly, making it an effective screening tool. Also the use of POCT can potentially reduce waiting time.
Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore. Electronic address: toochowwei@gmail.com.
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Too
Department of Pathology, Singapore General Hospital, 20 College Road, Academia, Singapore 169856, Singapore. Electronic address: ng.wai.yoong@sgh.com.sg.
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Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore. Electronic address: tan.chin.chong@sgh.com.sg.
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Tan
Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore. Electronic address: muhd.illyyas.mahmood@sgh.com.sg.
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Mahmood
Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore. Electronic address: tay.kiang.hiong@sgh.com.sg.
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Tay
D003287:Contrast Media / Q000009:adverse effects*; D003404:Creatinine / Q000097:blood*; D003920:Diabetes Mellitus; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D019095:Point-of-Care Systems; D051437:Renal Insufficiency / Q000139:chemically induced* / Q000175:diagnosis / Q000517:prevention & control; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires
D003287:Contrast Media; D003404:Creatinine
CT; Contrast agent; Kidney diseases