Reliability and clinical validity of a technique to assess lifetime illicit injection drug use

A lifetime injection drug history is necessary to examine the impact of injection drug use on a physical health problem but it may cover time periods for which information and/or data reported may not be reliable. A test-retest study design was used to examine a technique of questioning persons about lifetime illicit injection drug use history (the Lifetime Injection History Questionnaire), including its reliability and relation to chronic venous disorders as an assessment of validity. Study participants included 104 persons (60 men, 44 women, M age = 49.3 years) provided services at a methadone maintenance treatment center located in a large industrial city in the Midwest. Kappa values for "ever injected" drugs ranged from 1.00 for heroin to .50 for nonprescription methadone (median = .75). High interclass correlations were found for youngest and oldest ages of injecting, years not injecting, and total injecting years (.90 to .98). Interclass correlation values for years injecting in the upper body and lower body were .79 and .70, respectively. Interrater reliability for the clinical portion of the venous disease assessment tool (the Clinical-Etiology-Anatomy-Pathophysiology - CEAP - classification) was high: .97, right leg; .94, left leg. Controlling for age, gender, comorbidities, and body mass index, a classification of injection drug use based on the Lifetime Injection History scales accounted for 32% of the variance in the clinical CEAP scores. This is the first study to examine years of injection drug use that takes periods not injecting drugs into consideration. Focused substance abuse questioning (eg, drug, route, years of use) may help clinicians evaluate health problems related to drug use.