Increase in Daily Steps During the Early Phase of a Physical Activity Intervention for Type 2 Diabetes as a Predictor of Intervention Outcome.

Abstract

This pilot study aimed to test whether increase in daily steps and day-to-day consistency in daily steps during the first several weeks of a physical activity intervention predicted outcomes. This was a secondary analysis from two concurrent studies testing a positive psychology-motivational interviewing intervention to increase physical activity and positive affect in individuals with type 2 diabetes. Steps were measured with accelerometers at study assessments (baseline, end-of-treatment, and 8-week follow-up) and were measured daily throughout the intervention by participants using provided pedometers. We calculated change in steps from intervention week 1 to week 3, along with variability in daily steps over the first 3weeks, using the best fitting regression line modeling their change. Multiple regression analyses tested whether these predictors were associated with change in physical activity at the end of treatment and at 8-week follow-up. Additionally, we explored the utility of specific cutoffs (e.g., 500 steps) for early step change using a minimum p-value approach. In 52 participants, larger step increases by week 3 predicted activity increase at end-of-treatment and follow-up. Variability in early steps was not associated with outcomes. Early increase cutoffs of 500 and 2000 steps may have practical relevance. Early response to a physical activity intervention appears to be a useful predictor of outcome and could be used to identify those unlikely to succeed in a given intervention early in treatment. ClinicalTrials.gov identifiers NCT03150199 and NCT03001999.