Want to convert Farenheit to degrees Celcius? There’s an app for that. Want to plan your next big car journey? There’s an app for that. Want to screen for minimal hepatic encephalopathy? Well according to research recently published in the journal Hepatology, there’s an app for that as well.

Minimal hepatic encephalopathy (MHE) refers to a mild form of brain dysfunction which can be caused by liver problems and so is particularly relevant for patients with cirrhosis. Those with MHE have increased difficulty performing complex and potentially dangerous tasks such as driving, and experience a reduced quality of life. But previous methods of diagnosis have suffered from low sensitivity and availability, so the convenience of having an iPhone app to diagnose patients represents a big step forward in this area.

The app in question is called ‘Stroop’, and is freely available from iTunes (here). It features a simple test which involves some coloured text being displayed on the screen, and subjects then having to touch the matching colour, out of a choice of three displayed at the bottom of the screen. In the simpler level, the displayed text consists merely of a number of pound signs, but there is also a more difficult level where the text is the name of a colour (for example, the word ‘RED’ might be written in a green font, in which case the correct response would be green). The app times how long it takes subjects to complete this task correctly a number of times, and this information can then be used to judge whether the subject has MHE.

To test the validity of the app as a diagnosis tool, the researchers compared it with several other methods which can be used to test for MHE, which they tried on a mixture of cirrhosis-sufferers and healthy patients. They found that Stroop provided accurate results and could therefore be of use as a point-of-care instrument to allow simple screening for MHE.

“This app can be used to rapidly select which patients are likely to benefit from further MHE testing and potential treatment, which has been lacking at this time,” said principal investigator Jasmohan Bajaj. “It can be translated into practice by clinic assistants, nurses or other non-MD professionals to add a cost-effective approach to the rapid diagnosis of MHE.”

Although it performed well in these tests, further investigations still need to be carried out to see how well Stroop does with different types of patient. For example, linguistic origin or differences in a patient’s colour sensitivity might affect their score on the test.