title: Interviewer-administered TLFB vs. self-administered computerized (A-CASI) drug use frequency questions: a comparison in HIV-infected drug users.
abstract: BACKGROUND
  Substance use can have major consequences among HIV patients. Interviewer- or self-administered modalities are widely used to measure drug use frequency. This often involves Timeline Follow-Back (TLFB) interviewer-administered measures, or self-administered computerized questions assessing similar information via Audio Computer-Assisted Self Interview (A-CASI). Little is known about agreement between these two modalities on drug use frequency in HIV-infected samples.
  
  
  METHODS
  Prior to randomization into a trial of brief interventions to reduce drug use, 240 HIV patients completed a baseline A-CASI assessment battery that included questions on drug use frequency, followed by an interviewer-administered TLFB. Each measure generated number of days patients used their primary drug in the prior 30 days. Agreement between TLFB and A-CASI modalities on days using primary drug was determined using intraclass correlation coefficients (ICC). Regression analysis tested the association of patient characteristics with discrepancies between TLFB and A-CASI modalities.
  
  
  RESULTS
  Overall agreement was excellent (ICC=.80), with little variation by primary drug, education, race, current drug treatment, binge drinking or years since HIV diagnosis. Gender, ethnicity (Hispanic vs. non-Hispanic) and age predicted differences in days used (p<0.05); the A-CASI modality reflected more days used than TLFB.
  
  
  CONCLUSIONS
  Measures of days used primary drug showed high agreement whether assessed by interviewer-administered TLFB or by questions self-administered via the A-CASI modality. Differences by gender, ethnicity and age suggest some caution in using the TLFB, although additional studies are needed. However, findings generally indicate that studies based on one assessment method or the other can be compared with reasonable confidence.
authors.affiliation: New York State Psychiatric Institute, New York, NY 10032, United States; San Diego State University/University of California, San Diego Joint Doctoral Program in Public Health (Epidemiology), San Diego, CA 92093, United States.
authors.forename: Erin
authors.initials: E
authors.lastname: Delker
authors.affiliation: New York State Psychiatric Institute, New York, NY 10032, United States; Columbia University Medical Center, New York, NY 10032, United States.
authors.forename: Efrat
authors.initials: E
authors.lastname: Aharonovich
authors.affiliation: New York State Psychiatric Institute, New York, NY 10032, United States; Columbia University Medical Center, New York, NY 10032, United States; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032, United States. Electronic address: deborah.hasin@gmail.com.
authors.forename: Deborah
authors.initials: D
authors.lastname: Hasin
mesh_terms: D000328:Adult; D000367:Age Factors; D055030:Drug Users / Q000523:psychology*; D005006:Ethnicity / Q000523:psychology; D005260:Female; D015658:HIV Infections / Q000523:psychology*; D006801:Humans; D007407:Interviews as Topic / Q000379:methods*; D008297:Male; D008875:Middle Aged; D057566:Self Report; D012737:Sex Factors; D019966:Substance-Related Disorders; D011795:Surveys and Questionnaires
keywords: Assessment; Audio Computer-Assisted Self Interview (A-CASI); HIV; Substance use; Timeline Follow-Back (TLFB)