A team of researchers from universities and hospitals across the East Coast examined why Instant Blood Pressure — a top-selling smartphone app that claims to estimate blood pressure — gets high user ratings in the iTunes app store, despite often giving inaccurate results.
To measure blood pressure, Instant Blood Pressure prompts a user to place their right index finger over their smartphone's rear camera lens while placing the device against their chest. In general, the app tends to underreport elevated blood pressures, the researchers wrote in their study, published in npj Digital Medicine Aug. 10.
To examine whether this underreporting actually improved users' perception of the app, the researchers asked study participants at five clinics to estimate their blood pressure prior to measuring it with the app. To assess user experience, the researchers had the participants complete a survey as their final step.
Most participants enjoyed using the app and perceived its results as accurate.
However, when Instant Blood Pressure displayed a blood pressure that was higher than the participant's own estimate, participants tended to report less enjoyment from the app and a lower likelihood of using it in the future.
From these results, the study authors concluded the app's potential underreporting of elevated blood pressures might have contributed to its success online.
"These data suggest reassuring app results from an inaccurate [blood pressure]-measuring app may have improved user experience, which may have led to more positive user reviews and greater sales," the study authors concluded. "Further studies are needed to confirm whether falsely reassuring output from other mobile health apps improve user experience and drives uptake."