The albumin to creatinine ratio (ACR) product (Healthy.io) is a smartphone-based diagnostic test for home use. It is used for semi-quantitative detection of microalbumin and creatinine, and the qualitative measurement of the ratio between them. The test is for people with diabetes, high blood pressure or other risk factors for chronic kidney disease (CKD). The ACR results help identify possible kidney disease and guide patient management and care. The technology consists of an ACR test kit and a mobile application containing image recognition software. This allows a smartphone to act as an ACR urine strip analyser.
The ACR test kit is sent to the patient in the post and contains all single-use equipment needed for in vitro ACR testing (testing outside the body). It includes:
a urine collection cup
an individually wrapped ACR urine reagent strip
an absorbent pad to remove excess liquid from the reagent strip
a colour-board to enable image recognition.
The patient also receives a text message from their healthcare provider inviting them to download the ACR app. The app can be installed on Android and iOS smartphones that meet the minimum hardware criteria. The app guides the patient through each step of the testing process using video, audio and text guidance. To do the test the user collects a urine sample using the urine collection cup. They then dip the reagent strip into the sample for 1 second, remove any excess liquid with the absorbent pad and place it on the colour-board. The user then waits 60 seconds before scanning the colour-board. The software algorithm analyses the scanned image. Once the test is complete, the app automatically and securely sends the analysed results to the referring clinician through the patient's electronic medical record (EMR). Healthy.io's ACR testing system is integrated into EMIS and SystmOne EMR providers. In addition, all ACR test results are automatically uploaded to a secure online portal where healthcare professionals can also view them.
This briefing focuses on Healthy.io's ACR product. Further home-use urine tests using smartphone technology are also available from the company. These include a multiparameter urinalysis test (Dip.io).
The innovative aspects are that it allows non-clinical users to do semi-quantitative ACR testing with a smartphone in their own home. Results can be shared with a clinician through EMR. This allows real-time results to be reviewed and followed up. Current standard of care for ACR urine testing involves asking the patient to collect a urine sample at home. They have to bring this back to the healthcare provider who then sends it to the lab for analysis.
ACR testing is recommended for adults at risk of CKD. This includes people with diabetes, hypertension and other risk factors including acute kidney injury, cardiovascular disease, structural renal tract disease, recurrent renal calculi or prostatic hypertrophy, multisystem diseases with potential kidney involvement, family history of end-stage kidney disease, opportunistic detection of haematuria, and prescribed drugs that have an effect on kidney function.
ACR testing should be done in people with diabetes and those without diabetes with a glomerular filtration rate (GFR) of less than 60 ml/min/1.73 m2. The presence of protein in the urine should be tested for by measuring ACR and testing for blood in the urine using a reagent strip. Current standard of care for urine ACR testing involves asking the patient to collect a urine sample at home which they bring back to the healthcare provider for lab analysis. If the first ACR reading is between 3 mg/mmol and 70 mg/mmol, it is recommended that a repeat test be done using another early morning sample. If the first ACR reading is 70 mg/mmol or more, a repeat sample does not need to be tested. A confirmed ACR reading of 3 mg/mmol or above should be seen as clinically important. Reagent strips are not recommended unless they can specifically measure albumin at low concentrations and express the results as an ACR. The strips used in Healthy.io's ACR home test enables this measurement.
The following publications have been identified as relevant to this care pathway:
The product is used for ACR screening in people at risk of CKD, such as those with diabetes and hypertension. The technology is for home testing of ACR and is done by patients. The app has simple explanations and videos with steps in real time for the patient to follow.
There are an estimated 3.9 million people diagnosed with diabetes in the UK (Diabetes UK's diabetes prevalence, 2019), and 13.9 million people over the age of 16 with hypertension in England (Public Health England's hypertension prevalence estimates for local populations, 2017). Despite guidance on ACR testing, the National CKD Audit (2017) found that only 54% of people with diabetes have relevant annual urinary ACR tests. For other groups (such as those with hypertension), ACR rates are below 30%.
The company states that the technology is currently being used for ACR home testing by 4 NHS centres. The technology is also in the NHS Innovation Accelerator and is part of the Greater Manchester Digital Health Accelerator.
The cost of home ACR testing was provided by the company. Currently, the estimated cost per person is £12.10 (excluding VAT), this includes:
£4.50, cost of diagnostic test
£2.10 for handling and shipping of test kits to a patient's home
£5.50 for patient engagement; follow up and EMR integration.
The estimate of £12.10 includes total costs associated with the technology. There are no additional upfront costs to the NHS for setting up the technology digitally and integrating it with usual care.
According to Shore et al. (2019), the estimated unit cost of standard quantitative urine testing is £6. This includes the cost for all components needed for in-clinic urinalysis, as well as the unit costs of an ACR test. The cost of standard care testing was based on economic considerations for Delphi in NICE's guideline on routine preoperative tests for elective surgery (appendix M).
The unit cost of a urine ACR test was estimated by some of the experts to be between £0.45 and £2.08.
The technology costs more per test than standard urine ACR testing but could be resource releasing if it results in an increase in the number of CKD diagnoses and reduced cases of subsequent end-stage renal disease and cardiovascular disease.
Economic modelling by Shore et al. (2019) claimed that, in people with diabetes who are non-compliant with standard ACR testing, the technology is associated with cost saving of around £2,000 per person over a lifetime. In this study, the cost of the technology was provided by the company. This included shipping and service charges which covered outreach, customer support and integration work. The claimed cost saving was driven by an estimated increase in the CKD diagnoses and reduced progression to end-stage renal failure.