Point of care creatinine testing in diagnostic imaging: A feasibility study within the outpatient computed tomography setting

Introduction: Although the risks associated with iodinated contrast administration are acknowledged to be very low, screening of kidney function prior to administration is still standard practice in many hospitals. This study has evaluated the feasibility of implementing a screening form in conjunction with point of care (PoC) creatinine testing as a method to manage the risks of post contrast acute kidney injury (PC-AKI) within the CT imaging pathway.

Method: Over an eight-week period 300 adult outpatients attending a UK CT department for contrast-enhanced scans were approached. Participants completed a screening questionnaire for co-morbidities linked to kidney dysfunction and consented to have a PoC and laboratory creatinine tests. Comparison was made against with previous baseline blood tests obtained within the preceding 3 months, as required by the study site. Participants were also invited to attend for follow up PoC and laboratory bloods tests at 48–72 h.

Results: 14 patients (4.7%) had a scan-day eGFR below 45mL/min/1.73m2, all identified through screening. The majority of patients (n=281/300; 93.7%) fell in the same risk category based on previous and scan-day blood results. Six PoC test failures were recorded on the scan day. The constant error between the Abbott i-STAT PoC scan-day measurements and the laboratory scan-day measurements was -3.71 (95% CI: -6.41 to -0.50). Five patients had an elevated creatinine (≥25% from baseline) post contrast administration, but no instances of PC-AKI (≥50% from baseline) were identified.

Conclusion: PoC creatinine testing is a practical method of ensuring renal function and is feasible in the radiology environment.