title: Agreement in alcohol consumption levels as measured by two different questionnaires.
abstract: OBJECTIVE
  We evaluated the agreement in reported alcohol consumption between a standard food frequency questionnaire (FFQ) and a risk factor questionnaire (RFQ) developed for a genetic epidemiologic study of breast cancer.
  
  
  METHODS
  The FFQ measured intake of alcoholic beverages by asking which of nine levels were consumed during a single time period. In contrast, the RFQ used open-ended questions to measure intake of alcoholic beverages during numerous time periods. Subjects (N = 765) completed both questionnaires at home.
  
  
  RESULTS
  Mean daily alcohol consumption levels were consistently higher in the FFQ than in the RFQ; for example, the mean alcohol consumption for all subjects was 7.0 g/day in the FFQ versus 5.3 g/day in the RFQ. Moreover, the RFQ overestimated the number of nondrinkers relative to the FFQ. Nonetheless, the Spearman correlation coefficients between daily alcohol consumption levels as measured by the two questionnaires were relatively high: total alcohol, r = 0.72; beer, r = 0.69; wine, r = 0.69; and distilled spirits, r = 0.54.
  
  
  CONCLUSIONS
  The reasonable agreement between these questionnaires supports the validity of historical alcohol consumption levels measured by the RFQ.
authors.affiliation: Department of Preventive Medicine, University of Southern California School of Medicine, Los Angeles 90033, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Witte
authors.forename: R W
authors.initials: RW
authors.lastname: Haile
mesh_terms: D000328:Adult; D000368:Aged; D000437:Alcoholism / Q000175:diagnosis* / Q000235:genetics / Q000523:psychology; D001943:Breast Neoplasms / Q000235:genetics / Q000523:psychology; D003237:Connecticut; D015930:Diet Records; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010555:Personality Inventory / Q000706:statistics & numerical data*; D011594:Psychometrics; D015203:Reproducibility of Results; D012306:Risk; D012650:Self Disclosure