JMIR Publications

ABSTRACT

Background:

eCohort Studies offer an efficient approach for data collection. However, eCohort studies are challenged by volunteer bias and low adherence. We designed an eCohort (eFHS) embedded in the Framingham Heart Study (FHS) to address these challenges and to compare the digital data to traditional data collection.

Objective:

Evaluate adherence of the eFHS app-based surveys deployed at baseline (time of enrollment into eCohort) and every 3 months up to one-year and compare baseline digital surveys with surveys collected at research center.

Methods:

We defined adherence rates as the proportion of participants who completed at least one survey at a given 3-month period and computed adherence rates for each 3 month period. To evaluate agreement, we compared several baseline measures obtained in the eFHS app survey to those at the in-person research center exam using the concordance correlation coefficient (CCC).

Results:

Among the 1948 eFHS participants (mean age 53 [SD 7] years, 57% women), we found high adherence to baseline surveys (89%), and a decrease in adherence over time (58% at 3 months , 52% at 6 months, 41% at 9 months and 40% at 12 months). eFHS participants who returned surveys were more likely to be women (adjusted odds ratio [aOR] 1.68, 95% CI 1.20 -2.34) and less likely to be smokers (aOR 0.53, 95% CI 0.32-0.92). Compared to in-person exam data, we observed moderate agreement for baseline app-based surveys of physical activity index (PAI) (mean difference=2.27, CCC=0.56) and CES-D (mean difference=-0.91, CCC=0.66) and high agreement for average drinks per week (mean difference=0.54, CCC=0.82).

Conclusions:

App-based survey measurements had moderate to high agreement with research center measures. We observed high adherence to baseline surveys, but declining adherence over one year. Further investigation is needed to improve long-term adherence.