Point-of-care creatinine testing in radiology

The necessary administration of image-enhancing agents to patients prior to radiological investigation is associated with risk of two serious adverse effects: nephrogenic systemic fibrosis (NSF) and contrast-induced nephropathy (CIN). The risk only applies to those patients with renal disease, either acute kidney injury (AKI) or chronic kidney disease (CKD). 

Measurement of plasma creatinine and calculation of estimated glomerular filtration rate (eGFR) provides the means for assessing renal function and it is important to have knowledge of recent eGFR for patients at risk of NSF and CIN before proceeding with administration of image-enhancing agent. 

Best safety practice demands that if recent eGFR is not available, the radiological investigation should be cancelled until plasma creatinine measurement is arranged and eGFR result is available. To address this problem some radiological departments have introduced, or are considering introducing, point-of-care creatinine testing. 

This allows rapid assessment of patient renal function within the department, immediately prior to radiological investigation. This policy was recently implemented at Massachusetts General Hospital where researchers have conducted a study aimed at evaluating the impact, including cost effectiveness, of the policy. 

Over a 7-month study period 5.3 % of patients presenting for radiological investigation did not have a recent eGFR and required point-of-care creatinine measurement/ eGFR (total number of measurements 3087, i.e. 441 per month). Of these, 74 % had normal eGFR, allowing image-enhanced scan to proceed without further consideration. 

For the remaining patients with abnormal eGFR, a decision to continue with image-enhanced scan was made in 74 % of cases and for the remaining 26 %, considered at high risk of either NSF or CIN, the scan was performed without prior administration of image-enhancing agent. 

The researchers calculated that each point-of-care creatinine measurement cost USD 10.06 compared with USD 5.32 for creatinine measurement in the central laboratory; the incremental cost of each point-of-care test was thus USD 4.74. 

They judge that the cost of delaying and rescheduling scan because creatinine/eGFR is not available far exceeds USD 4.74, and conclude that point­-of-care creatinine testing in radiology is ”cost effective and improves clinical operations” at their hospital.