Cost-effectiveness of screening for unhealthy alcohol use with % carbohydrate deficient transferrin: results from a literature-based decision analytic computer model

Abstract

Background: The %carbohydrate deficient transferrin (%CDT) test offers objective evidence of unhealthy alcohol use but its cost-effectiveness in primary care conditions is unknown.

Methods: Using a decision tree and Markov model, we performed a literature-based cost-effectiveness analysis of 4 strategies for detecting unhealthy alcohol use in adult primary care patients: (i) Questionnaire Only, using a validated 3-item alcohol questionnaire; (ii) %CDT Only; (iii) Questionnaire followed by %CDT (Questionnaire-%CDT) if the questionnaire is negative; and (iv) No Screening. For those patients screening positive, clinicians performed more detailed assessment to characterize unhealthy use and determine therapy. We estimated costs using Medicare reimbursement and the Medical Expenditure Panel Survey. We determined sensitivity, specificity, prevalence of disease, and mortality from the medical literature. In the base case, we calculated the incremental cost-effectiveness ratio (ICER) in 2006 dollars per quality-adjusted life year ($/QALY) for a 50-year-old cohort.

Results: In the base case, the ICER for the Questionnaire-%CDT strategy was $15,500/QALY compared with the Questionnaire Only strategy. Other strategies were dominated. When the prevalence of unhealthy alcohol use exceeded 15% and screening age was <60 years, the Questionnaire-%CDT strategy costs 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 our literature-based decision analytic model set 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.

Fig. 1

Decision tree of four strategies to screen for unhealthy alcohol use in primary care. (A) A clinician can screen a primary care patient once for unhealthy alcohol by one of four strategies. (B) Once a patient tests positive by a screening test, he or she moves into the full assessment phase. In the full assessment, clinicians ask questions to determine if the test result is a true or false positive and determine if there is an alcohol disorder. Then, there is a probability that the clinician delivers a treatment (brief intervention for at-risk drinking or abuse) or refers to specialty alcohol treatment for alcohol dependence. Finally, there is a chance that the treatment succeeds, placing the unhealthy drinker into a safer health state. Patients then enter the Markov model in one of six health states (see Fig. 2).

Fig. 2

Markov model of health states defined by alcohol consumption (Non-Drinker, Safe Drinker, At-Risk Drinker) or the presence of an alcohol diagnosis (Alcohol Abuse, Alcohol Dependence, Alcohol Dependence in Recovery).

Fig. 3

Tornado diagram of one-way sensitivity analyses on important model parameters. The horizontal bars indicate the incremental cost-effectiveness ratio (ICER) of the Questionnaire-%CDT strategy compared with the Questionnaire Only strategy. Values in parentheses for each variable represent the range over which sensitivity analysis was performed as shown in Table 1. If the Questionnaire-%CDT strategy the Questionnaire Only strategy, then one end of the range is replaced by the value at which dominance occurs and is shown by an asterisk; the vertical line represents the ICER using the baseline value. An asterisk denotes the value for which the Questionnaire-%CDT strategy dominates the Questionnaire Only strategy. ICER, incremental cost-effectiveness ratio; QALY, quality adjusted life year.

Fig. 4

Two-way sensitivity analysis on the incremental cost-effectiveness ratio (ICER) as a function of the prevalence of unhealthy alcohol use and age at screening. The $/QALY values indicate the ICER range for the Questionnaire-%CDT strategy compared to Questionnaire Only strategy at specific combinations. QALY, quality adjusted life year.

Fig. 5

Percentage of simulations for which four strategies to screen for unhealthy alcohol use are cost-effective in a 50-year-old cohort of primary care patients. QALY, quality adjusted life year.