Purpose: The carbohydrate deficient transferrin (CDT) test offers objective evidence of unhealthy alcohol use (including at-risk drinking, abuse, and dependence), but its cost-effectiveness in primary care conditions is unknown.

Methods: We constructed a decision tree and Markov model to evaluate four strategies for detecting unhealthy alcohol use in adult primary care patients: 1) Questionnaire Only, using the validated 3-item Alcohol Use Disorders Identification Test-Consumption (AUDIT-C); 2) CDT Only; 3 Questionnaire followed by CDT (Questionnaire-CDT) if the questionnaire is negative; and 4) No Screening (case-finding only in which clinicians use no specific instrument to screen but discover unhealthy use through course of caring for patients). For those screening positive, clinicians performed more detailed assessment to verify and characterize unhealthy use. Clinicians could then offer brief intervention to at-risk drinkers and those with abuse and alcohol treatment to dependent drinkers. Eventually, all patients entered a Markov process in one of six health states based on alcohol use. We estimated screening costs using Medicare reimbursement for physician services and future costs with the Medical Expenditure Panel Survey. We determined screening test sensitivity and specificity, prevalence of unhealthy alcohol use, and alcohol related mortality from the medical literature. In our base case, we calculated the incremental cost-effectiveness ratio (ICER) in 2006 dollars /QALY for a 50 year old cohort. We also performed 1-way and probabilistic sensitivity analyses on all parameters.

Results: In the base case, the ICER for the Questionnaire-CDT strategy cost $11,300 /QALY compared with the Questionnaire Only strategy and was favored in 64% of probabilistic sensitivity analysis simulations using a threshold of $50,000 /QALY. Other strategies were dominated. Results were sensitive to the efficacy of brief intervention, questionnaire and CDT sensitivity, prevalence of unhealthy alcohol use, age at screening, and positive CDT follow-up rates. When the prevalence of unhealthy alcohol use exceeded 15% and screening age was less than 60 years, the Questionnaire-CDT strategy cost less than $50,000 /QALY compared to the Questionnaire Only strategy.

Conclusions: Adding CDT to questionnaire based screening for unhealthy alcohol use was cost-effective in typical primary care conditions. Screening with CDT should be considered for adults up to the age of 60 when the prevalence of unhealthy alcohol use is 15% or more and screening questionnaires are negative.