Comparison of smartphone application-based vital sign monitors without external hardware versus those used in clinical practice: a prospective trial

Use of healthcare-related smartphone applications is common. However, there is concern that inaccurate information from these applications may lead patients to make erroneous healthcare decisions. The objective of this study is to study smartphone applications purporting to measure vital sign data using only onboard technology compared with monitors used routinely in clinical practice. This is a prospective trial comparing correlation between a clinically utilized vital sign monitor (Propaq CS, WelchAllyn, Skaneateles Falls, NY, USA) and four smartphone application-based monitors Instant Blood Pressure, Instant Blood Pressure Pro, Pulse Oximeter, and Pulse Oximeter Pro. We performed measurements of heart rate (HR), systolic blood pressures (SBP), diastolic blood pressure (DBP), and oxygen saturation (SpO₂) using standard monitor and four smartphone applications. Analysis of variance was used to compare measurements from the applications to the routine monitor. The study was completed on 100 healthy volunteers. Comparison of routine monitor with the smartphone applications shows significant differences in terms of HR, SpO₂ and DBP. The SBP values from the applications were not significantly different from those from the routine monitor, but had wide limits of agreement signifying a large degree of variation in the compared values. The degree of correlation between monitors routinely used in clinical practice and the smartphone-based applications studied is insufficient to recommend clinical utilization. This lack of correlation suggests that the applications evaluated do not provide clinically meaningful data. The inaccurate data provided by these applications can potentially contribute to patient harm.