Quality of Physical Activity Apps: Systematic Search in App Stores and Content Analysis (Preprint)
BACKGROUND Physical inactivity is a major contributor to the development and maintenance of chronic diseases. Mobile health apps (MHA) to foster physical activity have the potential to assist in behavior change. However, the quality of MHA available in the app stores is hard to assess for endusers and health care providers. OBJECTIVE The present study aimed at systematically reviewing and analyzing the content and quality of physical activity apps. Moreover, the privacy and security measures were assessed. METHODS A web crawler was used to systematically search for apps promoting physical activity in the Google Play and Apple App Store. Two independent raters used the German Mobile Application Rating Scale (MARS) to assess app quality. Furthermore, app characteristics, content and functions, privacy and security measures were assessed. Correlation between user star ratings and the MARS was calculated. Exploratory regression analysis was conducted to determine relevant predictors for overall quality. RESULTS 312 of 2,231 identified apps met inclusion criteria. Results indicate that overall quality was moderate (M = 3.60, SD = 0.59, range = 1-4.75). The scores of the subscales were: information (M = 3.24, SD = 0.56, range = 1.17-4.4), engagement (M = 3.19, SD = 0.82, range = 1.2- 5), aesthetics (M = 3.65, SD = 0.79, range = 1- 5), and functionality (M = 4.35, SD = 0.58, range = 1.88- 5). For none of the included apps an efficacy study could be identified. Data and privacy features were mainly not applied. Average user ratings showed significant small correlations with the MARS rating (r =.22; 95% CI: 0.08-0.35; P < .001). The number of content and function was predictive for overall quality, whereas app store and price were not. CONCLUSIONS There is an extensive quality range within apps for physical activity with moderate overall quality ratings. Given the present privacy, security, and evidence concerns inherent to most rated apps, their medical use is questionable. There is a need for open-source databases of expert quality ratings to foster informed health care decisions in users and health care providers. CLINICALTRIAL