Validation of a Single Screening Question for Problem Drinking

Previous studies have explored the utility of a single question about the frequency of drinking 5 or more drinks at one time. Drinking 5 or more drinks on one occasion at least once in the past year had a sensitivity of 86% and a specificity of 63% in detecting past-year alcohol dependence.²³ In an emergency center–based study with a positive screening result defined as heavy drinking at least monthly, sensitivity was 58% and specificity 85%.²⁴ The authors of these reports concluded that a single question about the frequency of heavy drinking was inadequate in screening for problem drinking. However, the question we used inquired about the last occasion of heavy drinking not the usual frequency and used different thresholds for men and women, narrowing the sex differences in sensitivity and specificity found in previous work using a single threshold.¹¹

The single question we used compares favorably with the CAGE²⁵ and the Alcohol Use Disorders Identification Test (AUDIT).²⁶ For the single question, the area under the ROC curve is 0.90 for problem drinking and 0.81 for alcohol use disorders only. With the AUDIT,²⁷ the area under the ROC curve was 0.83 to 0.90 in a variety of settings in detecting alcohol use disorders^26,28,29 (hazardous drinkers not included) and 0.88 in detecting problem drinking.²⁹ With the CAGE questions the area under the ROC curve was 0.89 in one study²⁵ and 0.68 to 0.88 in a variety of sex-ethnic subgroups in another²⁶ for detecting alcohol use disorders only.

The criterion standards we used are reliable and valid.^14,30 Although they were negative in 27 patients with alcohol levels of 0.22 mmol/L or greater in whom intoxication may have limited the validity of self-report, 22 of those 27 patients had a positive screening result with the single question.

Limitations

Several limitations of our study should be noted. The interviewer was aware of the patient’s response on the screening question, and this may have led to ascertainment bias. However, the interview was the same for all participants whether their screen produced positive or negative results, and the DIS is a fully structured interview, minimizing this potential bias.

The study is limited by its nonparticipation rate of 30%. Of eligible injured patients from covered emergency department shifts 15.4% were missed, either because interviewers were busy with other participants or because the patient had severe injuries that precluded interview. Another 12.2% declined to participate. The utility of the screening question in these patients is unknown.

The single question did not perform as well for African Americans as it did for whites; its sensitivity and specificity, however, are clinically useful in both groups. Consistent with the population of central Missouri, the study included few members of other ethnic groups, and the question’s utility in those groups needs study.

The generalizability of our findings may be limited. The study included only injured patients presenting for care to emergency centers in central Missouri. However, alcohol-related injury is a major source of morbidity and mortality especially among young adults, and brief interventions in emergency centers are efficacious.³¹ We have little reason to expect the question used in this study would be less effective in other clinical settings.

We examined only one approach to screening. However, the screening question used in this study was selected in advance and remained unchanged throughout data collection. Some screening instruments³² developed post hoc from a longer list of questions have been validated in separate samples,²⁴ but others^33,34 have not.^35,36

Given the morbidity associated with hazardous drinking and the efficacy of brief interventions, screening should include hazardous drinking as well as alcohol use disorders, which we did in this study. Studies of other screening instruments have generally tested their utility only in detecting alcohol use disorders, in which the single question was less specific. Although our study did not address the issue, the single question probably would not identify patients in long-term recovery from a past alcohol use disorder, especially those abstinent for more than a year.

Conclusions

Further study is needed to determine whether clinicians will find this single question easier to apply and whether problem drinkers find it more engaging than alternative screening instruments. The goal of screening is to identify problem drinkers and to engage them effectively in the process of change.³⁷ Different screening approaches—and different ways of following up positive screen results—may vary in their ability to help problem drinkers move toward change.

A single question about the last occasion of heavy drinking has clinically useful sensitivity and specificity in detecting hazardous drinkers and current alcohol use disorders. The question is simple enough that it could be used, as is a question about tobacco use,³⁸ as part of the taking of routine vital signs. If the question used in our study were adopted, it could efficiently identify which patients require further discussion about their drinking habits, with positive and negative predictive values of 77% and 92% in this emergency center population, approximately 52% and 97%, respectively, in a typical population-based sample. That in turn could lead to more frequent use of effective brief intervention and referral strategies, thereby potentially decreasing society’s burden of alcohol-related harm.