Dietary methodology: advancements in the development of short instruments to assess dietary fat

Validation of the MEDFICTS dietary assessment questionnaire in a diverse population

BACKGROUND

The National Cholesterol Education Program (NCEP) recommends MEDFICTS, a rapid screening instrument for dietary fat, to assess adherence to the Adult Treatment Panel (ATP) III Therapeutic Lifestyle Changes (TLC) diet (score <40 points indicates intake of <7% of energy from saturated fat, <30% of energy from total fat, and <200 mg dietary cholesterol/day). MEDFICTS has only been validated in small, select populations and its utility in diverse clinical settings is unknown.

OBJECTIVE

To evaluate the ability of MEDFICTS to identify individuals who are nonadherent to a TLC diet in an ethnically diverse population that includes both English- and Spanish-speakers.

DESIGN

MEDFICTS was administered concurrently with the Gladys Block Food Frequency Questionnaire to participants (n=501; mean age 48+/-13.5 years; 36% nonwhite; 66% female) in the National Heart, Lung, and Blood Institute Family Intervention Trial for Heart Health (FIT Heart) at the baseline screening visit. Reliability and validity analyses were conducted overall and by sex, age, and race/ethnicity.

RESULTS

MEDFICTS score correlated significantly with percentage of energy from saturated fat (r=0.52, P<0.0001), percentage of energy from total fat (r=0.31, P<0.0001), and milligrams per day of dietary cholesterol (r=0.54, P<0.0001). Sensitivity of MEDFICTS to correctly identify TLC diet adherence was 85.7% and did not differ significantly by sex, age, or race/ethnicity. Specificity of MEDFICTS to correctly identify nonadherence to the TLC diet was low (56.9%) and significantly worse for women than men (48.4% vs 72.9%; P<0.0001), but did not differ significantly in older vs younger participants or among white, black, or Hispanic participants.

CONCLUSION

Our data suggest that sex-specific recalibration of MEDFICTS may improve specificity and clinical utility.