1 Recommendations

1.1

Point-of-care creatinine devices ABL800 FLEX, i‑STAT Alinity and StatSensor, which calculate estimated glomerular filtration rate (eGFR), are recommended to assess kidney function to guide decisions on whether to use intravenous contrast during an outpatient CT scan in adults. They should only be used when current practice is that a recent eGFR result must be available before a person has a CT scan with intravenous contrast and if all the following apply:

a person presents for a CT scan without a recent eGFR result
the person has risk factors for acute kidney injury
clear governance structures for point-of-care testing are in place.

1.2

Take age, sex and ethnicity into account when assessing risk of acute kidney injury using a questionnaire-based tool (see section 4.13).

1.3

Point-of-care creatinine devices ABL90 FLEX PLUS, Dri‑chem NX500, epoc Blood Analysis System, and Piccolo Xpress are not recommended to assess kidney function to guide decisions on whether to use intravenous contrast during an outpatient CT scan. This is because there are insufficient data to assess their diagnostic accuracy.

1.4

Further research is recommended to:

better understand the level of risk of contrast-induced acute kidney injury (see section 5.1)
identify the most appropriate tool for identifying risk factors (see section 5.2)
monitor the effect of implementation on patient experience and efficiency in radiology departments (see section 5.3).

Why the committee made these recommendations

It's important to check whether the kidneys are working properly by measuring eGFR before a contrast-enhanced CT scan. This is because the contrast agent can cause acute kidney injury in people with low eGFR.

Normally, referrers will provide a laboratory eGFR measurement before a CT scan appointment but in cases where a person presents without a recent eGFR result, point-of-care creatinine devices can measure creatinine levels and be used to calculate eGFR rapidly. This means that people who do not have a recent eGFR result will not need to have their CT scan cancelled so that their creatinine can be measured in the laboratory. Referrers providing a laboratory eGFR measurement before a CT scan appointment remains the optimal approach, and this approach should be encouraged to avoid higher numbers of patients needing point-of-care (POC) creatinine measurement before a contrast-enhanced CT scan.

Evidence suggests that the ABL800 FLEX, i‑STAT Alinity and StatSensor all have acceptable accuracy in determining when eGFR is low (below 30 ml/min/1.73 m²). It was not possible to determine whether one is more accurate than another. Economic modelling shows that all 3 devices offer value for money to the NHS when compared with delaying scans for laboratory creatinine testing, although more people with an eGFR of less than 30 ml/min/1.73 m²may be identified if they had laboratory testing. Using the devices can also avoid cancelling and rebooking CT scans, which is important for patients. The devices offer the most value for money when:

they are used only for people who have one or more risk factors for acute kidney injury and
cancelled CT scan appointments cannot be offered to other people.