Single-item and multiple-item measures of adherence to public health behavior guidelines were incongruent.

OBJECTIVE: Physical activity (PA) and fruit and vegetable consumption may prevent or delay the development of hypertension and cardiovascular diseases. We examined adherence rates to single and combinations of Dutch public health guidelines for these behaviors by comparing and combining two self-report measurements. STUDY DESIGN AND
SETTING: The behaviors of 2,568 Dutch participants aged 45-70 years were measured using one item and multiple items. Patients were classified as meeting or not meeting a guideline using both measurements separately and combined.
RESULTS: Substantially more participants met guidelines when measured with multiple items than when measured with one item, with differences of 21-39%. Combined measurements resulted in fewer participants meeting guidelines than multiple-item measurements used alone. Combined measurements showed that 17%, 12%, and 34% of participants met the guidelines for fruit and vegetable consumption and PA, respectively; only 3% met all three guidelines. Sociodemographic variables explained less than 4% of the variance of congruency between single- and multiple-item measurements.
CONCLUSION: When assessing adherence rates, the level appears dependent on the method of self-report chosen. Hence, more research must analyze which adherence measurement will result in valid responses and which variables are associated with congruency between single- and multiple-item measurements.