UCLA

BACKGROUND

There are multiple strategies but no gold standards for self-monitoring diet, physical activity (PA), and perceived stress. Although self-monitoring is a core element of self-management and behavior change, the success of mHealth behavioral tools is dependent on validity and reliability, which is lacking in evidence. African-American and Latina mothers in the United States are high priority populations for applications addressing diet, PA, and stress because mothers typically increase body mass index (BMI) for several years after childbirth and the risks of obesity and its’ sequelae diseases are elevated among minority populations.

OBJECTIVE

This pilot study examined inter-method reliability and concurrent validity of smartphone-based self-monitoring by ecological momentary assessments (EMA) and daily-diaries for diet, stress, and PA compared to brief recall measures, anthropometric bio-measures and bloodspot biomarkers.

METHODS

A purposive sample (n=42) of primarily African-American (39%) and Latina (44%) mothers (about one-third normal weight, overweight, or obese) was assigned AndroidTM smartphones with the Ohmage application to self-monitor diet, perceived stress, and PA over six months. Participants were assessed at 3- and 6-month follow-ups. Recall measures included brief food frequency screeners, PA assessments adapted from NHANES, and the PSM-9 stress measure. Anthropometric bio-measures included BMI, body fat, waist circumference, and blood pressure (BP). Bloodspot assays for Ebstein-Barr Virus (EBV) and C-Reactive Protein (CRP) were used as biomarkers of systemic load and stress. EMA and daily diary questions assessed perceived quality and quantity of meals, perceived stress levels, and moderate, vigorous, and light PA. Units of analysis were follow-up assessments (n=29 to n=45 depending on domain) nested in participants (N=29 with sufficient data for analyses). Correlations, R2 statistics, and multivariate linear regressions assessed strength of associations between variables.

RESULTS

Almost all participants (93%) completed the study. Inter-method reliability between smartphone EMA/diary reports and their corresponding recall reports was highest for stress and diet, with correlations ranging from .27 to .52 (with p<.05), but was unexpectedly low for PA with no significant associations. Concurrent validity was demonstrated for diet EMA/diary reports with systolic BP (r = -.32), CRP (r = -.34), and moderate and vigorous PA recalls (r = .35 to .48), suggesting co-variation between healthy diet and PA behaviors. Stress EMA/diary reports were not associated with EBV and CRP biomarkers. Moderate and vigorous PA diary reports were negatively associated with BMI and body fat (r = -.35 to -.44, p<.05).

CONCLUSIONS

Brief smartphone EMA may be valid and reliable for long-term self-monitoring of diet, stress, and PA. Lack of inter-method reliability for PA measures is consistent with prior research. More research is needed on the efficacy of smartphone self-monitoring for self-management and behavior change support.