JMIR Publications

ABSTRACT

Background:

Smartphones are often equipped with inertial sensors that measure individuals' physical activities. However, their role in remote monitoring of the patients' physical activities in telemedicine needs to be adequately explored.

Objective:

The main objective of this study was to explore the correlation between a participant's actual daily step counts and the daily step counts reported by their smartphone. In addition, we inquired about the usability of using smartphones for collecting physical activity data.

Methods:

This prospective observational study was conducted on patients undergoing lower limb orthopedic surgery and a group of non-patients as control. The data from the patients were collected from 2 weeks before surgery until four weeks after the surgery, while the data collection period for the non-patients was two weeks. The participant's daily step count was recorded by physical activity trackers employed 24/7. In addition, a smartphone application collected the number of daily steps registered by the participants' smartphones. We compared the cross-correlation between the daily steps time-series taken from the smartphones and physical activity trackers in different groups of participants. We also employed mixed modeling to estimate the total number of steps, using smartphone step counts and the characteristics of the patients as independent variables. The System Usability Scale was used to evaluate the participants' experience with the smartphone application and the physical activity tracker.

Results:

Overall, 1067 days of data were collected from 21 patients (11 females) and 10 non-patients (6 females). The median and IQR for the cross-correlation coefficient on the same day was 0.70 [0.53–0.83]. The correlation in the non-patients was slightly higher than in the patients (0.74 [0.60–0.90] and 0.69 [0.52–0.81], respectively). The likelihood ratio tests on the models fitted by mixed effect methods demonstrated that the smartphone step count was positively correlated with the physical activity tracker's total number of steps (χ2 = 34.7, p < .00001). In addition, the usability score for the smartphone app was 78 [73-88] compared to 73 [68-80] for the PA tracker.

Conclusions:

Considering the ubiquity, convenience, and practicality of smartphones, the high correlation between the smartphones and the total daily step count time-series highlights the potential usefulness of smartphones in detecting the change in the number of steps in remote monitoring of the patient's physical activity.