Table 1.

Accuracy problems in studies using physiological measurements by smartphone apps

Measure	App	Smartphone	Participants	Finding	Study
Blood pressure	Instant Blood Pressure	iPhone 5 and 6.	85 patients and staff; 53% with hypertension.	Measures “were highly inaccurate”	Plante et al. (2016)
Heart rate	Instant Heart Rate Heart Fitness Whats My Heart Rate Cardio Version	iPhone 4 and 5.	108 patients, exluding those in critical condition.	“substantial performance differences” between the four apps	Coppetti et al. (2017)
Heart rate Blood pressure Oxygen saturation	Instant Blood Pressure Instant Blood Pressure Pro Pulse Oximeter Pulse oximeter Pro	iPhone 5S	100 healthy participants	“applications evaluated do not provide clinically meaningful data” “inaccurate data.. can potentially contribute to patient harm”	Alexander et al. (2017)
Heart rate	Runtastic Heart Rate Monitor Instant heart rate+	iPhone	15 regularly active college students	“Poor correlation to ECG” during moderate to high intensity exercise	Bouts et al. (2018)
Step counting	Argus: calorie counter and step	Android phones: Samsung, OnePlus, Moto, Oppo, Galazy, Huawei, LG, Google, Sony and Agora running Android 4.4 to 8.1 Apple: iPhone 6, 6S, 7, 8, running iOS10.3–11.4.	48 healthy participants	“extraordinarily large error ranges for both..phones” “appear unsuitable to detect steps in short, slow, or non-stereotypical gait patterns”	Brodie et al. (2018)
Sleep	Sleep time	iPhone 4 s and 5	20 participants with no sleep disorder	“absolute parameters and sleep staging…. correlate poorly with polysomnography”	Bhat et al. (2015)
Sleep	MotionX 24/7	iPhone 4	78 children and adolescents with suspected sleep disordered breathing	“did not accurately reflect sleep or wake and should be used with caution”	Toon et al. (2016)