Assessing Craving for Alcohol : Part 2

by National Institute of Health

(Page 2 of 5)

As with reliability, several types of validity exist. Some of the most common measures of validity include construct validity, external validity, discriminant validity, and criterion-oriented validity. Construct validity refers to the degree to which results from an instrument reflect the underlying quality (craving) that the instrument is trying to measure. External validity describes the degree to which the results obtained with the instrument agree with results obtained with a different instrument with established validity. Discriminant validity indicates an instrument's ability to accurately discriminate between populations with and without the quality of interest. For example, for alcohol craving, discriminant validity might be tested by whether the instrument discriminates alcoholics from nonalcoholics. Finally, criterion-oriented validity refers to how well scores on an instrument correlate with behaviors that are supposedly relevant to the quality being measured. For example, good criterion-oriented validity might be suggested if a craving instrument yields high scores for people who are willing to work for a drink in an experimental setting and low scores for people who are not willing to work for alcohol.

Most clinical and research assessments of craving have relied on brief measurement scales with unknown psychometric properties. In fact, the majority of investigators and clinicians have used instruments consisting of only a single question to assess craving. Typically, these instruments ask questions such as, "How strong is your craving for alcohol?" or "How much do you crave an alcoholic beverage when you have gone without a drink for 1 to 2 days?" Because these indices consist of only one question, it is impossible to obtain an estimate of their internal consistency. Nonetheless, single items or brief scales that capture important aspects of the craving construct may demonstrate satisfactory interrater or test-retest reliability. Therefore, brief scales may provide especially useful tools where multiple craving assessments are desired and lengthier instruments would be impractical.

Alcohol cravings are generally thought to arise either from the desire to experience alcohol's positive effects (positive reinforcement) or from the desire to avoid the negative effects of withholding alcohol, such as withdrawal symptoms (negative reinforcement).More recent models have suggested other important dimensions of craving, such as the desire and intention to consume alcohol, lack of control over alcohol use, and preoccupation with drinking-related thoughts and/or behavior. It is possible that certain aspects of craving characterize the experience of some alcoholics better than that of other alcoholics. Similarly, patients' craving descriptions may change throughout the treatment process, necessitating measures that are sensitive to the dimensions of craving experienced at different time points or under differing circumstances. The development of indices that are sensitive to such differences may be helpful in the development of treatment plans based on the relative importance of various features of craving across individual patients and over time.

Unfortunately, the brevity of most available scales has not permitted researchers and clinicians to disentangle the multiple aspects of craving. Several newer multi-item instruments that take into account various dimensions of craving are discussed in the section "Methods of Assessing Alcohol Craving," below. One should not assume, however, that each of these scales measures the same dimensions of craving or even that the same dimensional structure would be produced by the same instrument when administered to different samples of alcoholics.

Timeframe of Assessment

Another critical aspect to consider when measuring craving is the timeframe of the assessment. Craving measures fall into two main categories with respect to their timeframe: state measures, which focus on the patient's current craving status, and global measures, which ask the patient to describe his or her general experience of craving over the course of 1 day, 1 week, 1 month, or an even longer time period.

The specific timeframe of the assessment instrument used should depend on the particular goals of the researcher or clinician administering the assessment. State measures are useful for assessing patients' craving experiences at specific time points (during treatment sessions that expose the patients to alcohol or use other cognitive-behavioral approaches) and for determining changes in craving over time. Such immediate assessments of craving are particularly important in experimental settings, because they help researchers to better understand the neurological, biochemical, psychophysiological, cognitive, subjective, and emotional mechanisms involved in craving.

State measures may be less useful, however, in analyses assessing the relationship between craving and general alcohol use behavior. Studies typically have found only insignificant or weak relationships between the strength of subjective craving at a given time point and concurrent or subsequent alcohol use behavior. This lack of a correlation may result from the presence of multiple factors that may differentially influence subjective ratings and behavior. Examples of such factors include the patient's internal state (mood or withdrawal symptoms), the presence of environmental cues related to past drinking, the perceived availability of alcohol, and the patient's current motivation to consume alcohol.

In contrast to state measures of craving, global craving assessments tend to show a stronger relationship with actual alcohol use. One potential explanation for this stronger correlation is that alcoholdependent people may be able to resist drinking during brief instances of craving, but cravings that occur frequently may have a cumulative impact on drinking. Therefore, instruments that ask patients to integrate their cravings over longer periods of time may offer a more reliable assessment of the extent to which cravings have caused distress or interference for the patient. This may, in turn, bear a closer connection to whether the person will engage in drinking behavior.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.