Authored by: Dr Matthew Lee; BMSc, MBBS, MSc

Reviewed by: Dr Kiran Roest; PhD on August 2024

What’s in this Article?

• How do we measure the accuracy of devices such as PocDoc?
• How accurate is PocDoc?
• How does PocDoc’s accuracy compare to other health checks?
• How can PocDoc aid in the primary prevention of cardiovascular diseases?

How do we measure the accuracy of devices such as PocDoc?

The accuracy of diagnostic devices such as PocDoc is determined by 2 key factors- precision and bias.

1) Precision is the ability of a device to consistently give the same reading when testing the same sample repeatedly. In simpler terms - a precise device will produce identical results each time it is used.

2) Bias, on the other hand, is the ability of a device to give a reading very close to a reference value (also called the known value).

• A device with a positive bias gives a reading above a reference value.

• A device with a negative bias gives a reading that falls below a reference value.

Manufacturers of devices are aiming for high precision and low bias which corresponds to good accuracy. A device with high precision and low bias means that patients and clinicians will be able to trust the results they receive.

How accurate is PocDoc?

PocDoc’s accuracy results have been published in the peer-reviewed Journal of Biosensors and Bioelectronics. This study, which was done in collaboration with the University of Sunderland, involved a detailed performance evaluation which analysed 125 blood samples from patients.

PocDoc’s results were compared with reference lab results using a “gold standard” commercial analyser. Two assessments were conducted:

1) The accuracy of the PocDoc results.

2) The impact of the difference between PocDoc and the reference analyser on the clinical outcome for patients; this means whether a patient would have been recommended a different treatment pathway based on the result.

As discussed above, there are 2 main components to accuracy: precision and bias. This feed into an overall accuracy measure called the Total Analytical Error (TAE):

1) PocDoc’s precision results are reported as a Coefficient of Variation (%) – that is, the level of variation that can be expected from repeated measurements of the same known value.

• PocDoc’s Coefficient of Variation was below 4% for all cholesterol measurements.

2) PocDoc’s bias results, which refer to the difference between PocDoc and a reference lab value, are approximately:

• +1% for Total Cholesterol

• -4 % for Triglycerides

• -4 % for HDL cholesterol

There are notable day-to-day variations in lipid levels, meaning your lipid levels will change from one day to the next. According to the National Cholesterol Education Program guidelines, this variation measures:

• Total Cholesterol up to 5%

• Triglycerides up to 20%

• HDL-Cholesterol up to 10%

Therefore, the PocDoc bias results are clinically insignificant compared to normal biological variation.

Total Analytical Error

Total Analytical Error (TAE) combines the precision and bias values into one measurement. International organisations, such as the National Cholesterol Education Program (NCEP), publish TAE targets for medical device developers.

PocDoc’s results showed that our TAE is within NCEP guidelines.

The table highlights PocDoc’s TAE scores in comparison to the official National Cholesterol Education Program Guidelines (NCEP)

The second assessment of PocDoc’s accuracy looked at the clinical recommendations that would be given were a patient assessed using PocDoc or the reference laboratory analyzer. The results showed that regardless of which device was used, the same clinical recommendation would be given. This means that PocDoc can be used as an alternative to traditional laboratory tests.  

How does PocDoc compare to other health checks?   

The results from PocDoc's accuracy assessments revealed that the technology’s accuracy is comparable to that of other devices, including the Cobas c503, PTS CardioChek, and Afinion AS100/Cholestech LDX.   

Table showing the accuracy of PocDoc in comparison to their competitors   

PocDoc produced similar results and, in some cases, outperformed these other health checks. In all cases, PocDoc was the only health check to offer additional services that made it more convenient and accessible, including traceable results and full health check follow-up services.  

How can PocDoc aid in primary prevention of cardiovascular diseases?

PocDoc’s Healthy Heart Check measures the full lipid marker panel and integrates the results directly within the QRISK3 algorithm. This provides users with a more detailed picture of their overall heart health.

The QRISK3 result indicates an individual’s risk of cardiovascular disease (CVD), with individuals over 10% being classified as high risk. By identifying high-risk individuals and supporting them in their journey to decrease risk, PocDoc has potential to reduce the prevalence of CVD in the UK.