Kidney function testing prior to contrast-enhanced CT: a comparative cost analysis of a personalised risk-stratified...

To map current contrast-enhanced computed tomography (CT) pathways, develop a risk-stratified pathway, and model associated costs and resource use.

Phase 1 comprised multicentre mapping of current practice and development of an alternative pathway, replacing pre-assessment of estimated glomerular filtration rate (eGFR) with a scan-day screening questionnaire for risk stratification and point of care (PoC) creatinine. Phase 2 measured resource use and analysis of routinely collected data, used to populate a model comparing the costs of current and risk-stratified pathways in Phase 3.

Site variation across a range of processes within the clinical care pathway was identified. Data from a single centre suggested that 78% (n=347/447) could have avoided their pre-scan laboratory test as they did not have post-contrast acute kidney injury (AKI) risk factors. Only 24% of outpatients who underwent computed tomography (CT) would have identified risk factors, which would have prompted a scan-day PoC test. There was a 94% probability that the risk-stratified pathway was cost-saving, with an estimated 5-year potential cost saving of £69,620 (95% CI: -£13,295-£154,603). Although the cost of a laboratory serum creatinine test is cheaper than the PoC equivalent (£5.29 versus £5.96), the screening questionnaire ruled out the need for a large majority of the eGFR measurements specifically for the CT examination.

The present study proposes an alternative pathway, which has the potential to improve the efficiency of the current CT pathway. A multicentre appraisal is required to demonstrate the impact of embedding this new pathway on a wider NHS level, particularly in light of new diagnostic guidance (DG37) published by NICE.