the measurement of alcohol consumption and alcohol-related problems
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Australian Drug and Alcohol Review 1986; 5:309-310
The Measurement of Alcohol Consumption and Alcohol-Related Problems
Rob Sanson-Fisher Department of Behavioural Science in Relation to Medicine, Faculty of
Medicine, University of Newcastle, Newcastle, New South Wales. Our group became involved in the issue of
alcohol screening as a result of work that we were doing in general practice. We found ourselves dissatisfied with existing screening scales and decided to develop a psychometrically robust scale for use in that setting. It is a difficult research area and what I will do is briefly discuss what we have found and some of the directions we wilt be taking in the future.
Our first encounter with the issue of alcohol measurement related to how you might estimate alcohol consumption, since we wanted to find out whether general practitioners were accurate in judging which of their patients were high drinkers or low drinkers. So we needed to ensure, as much as possible, that we had a satisfactory measure of pat ient consumpt ion. We compared the traditional quantity-frequency method (QF) and the diary method of estimating consumption. As you may be aware, the QF asks "How much do you usually drink?" and then "How often do you usually do this?" It is broadly based and very commonly used in most studies looking at con- sumption rates. The diary method, on the other hand, uses a retrospective technique, and it asks "How much did you drink today?", "How much did you drink yesterday", and so on back over a week.
We compared these two measures using 778 general practice patients, and we classified patients as heavy drinkers if they drank 28 drinks or more a week. The QF failed to identify 78% of those patients detected as heavy drinkers by the diary method. Overall, patients also reported drinking significantly more on the diary measure than on the QF, with 10.5 standard drinks per week reported on diary versus 6.9 on the QF.
However, there were a few problems with this study. For example, while it was completed by the same individuals it was done in two settings. We asked the people to complete the QF in the doctor's office, and the diary was answered in
their home a day later. Furthermore, we did not look at order effects, that is, if you present the QF first versus the diary first.
We are currently trying to overcome these problems in a new study undertaken in an industrial setting. We are also looking at the test- retest reliability of both the QF and diary method of estimated consumption. At the same time, we are examining the stability of these measures over 6 and 12 month periods.
In our research, we also try to look at the validity of the consumption measures. We have compared 56 generalpractitioners' estimations of the drinking habits of 2,500 of their patients with the patients' self reports to look for concurrent validity. We found that the GPs only detected 27% of those people who were identified by their own self report as being heavy drinkers, suggest- ing that GPs are not very good at providing estimates of alcohol consumption amongst their patients. That is, concurrent validity is low. In a study of the interaction of sixty interns with 1,200 of their patients, we found that they only detected 12.7% of the heavy drinkers.
The most important form of validity is predic- tive validity. We are currently following 900 people, high, low, and medium drinkers, to find out whether the high consumers are more likely to have accidents in the work place, or greater absenteeism. While we were doing the work on consumption, it occurred to us that while only around 3% of the general practice population are above the recommended risk levels for drinking, alcohol-related problems are relatively high. We measured alcohol-related problems in the general practice population initially using the SMAST. We now see a number of problems with this and other such measures. These include the fact that most scales are unitary in nature. They treat alcohol-related problems as though they are a one dimensional concept/problem, while in practice they spread across many aspects of life. They can
affect an individual's family life; their personal relationships; their interactions with their chil- dren; and their financial and work functioning. They assume that if you have had a drinking problem in the past, you still have a drinking problem. It does not allow for the fact that people may move in and out of alcohol-related problems. Furthermore, these scales are concerned primarily with the diagnosis of "alcoholism' rather than with the low levels of alcohol-related problems likely to be apparent in community samples.
The psychometric characteristics of many of the existing tests of alcohol related problems are poor. The number of items in each category are small, not allowing an adequate examination of internal stability and they have been validated on clinical samples only. They often do not control for acquiescent response set. The tests are oriented towards severe rather than minor problems, and interestingly, they assume that there is a one-to- one relationship between drinking and alcohol- related problems. It seems to us that for a general practice population this may not be the case for two reasons. First, there is a group who do drink and yet experience no alcohol-related problems. Second, while not drinking themselves, those who coexist with a drinker may experience problems
from his/her drinking which might be considered alcohol-related. There is also a simplistic assump- tion that there is a linear relationship between consumption levels and alcohol-related problems. However, we have found that individuals con- suming minimal levals may have alcohol-related problems.
Consequently, we are currently developing a number of alcohol-related measures suitable for use in the general practice setting which are psychometrically sound and multifactorial in orientation. We are trying to develop a scale which is both reliable and valid. It is intended to detect minor alcohol-related problems in a general practice population. Most importantly, it is orien- tated towards both the person who is drinking and those who experience problems associated with someone else's drinking. We have trialled the acceptability of the test with 300 patients and are now looking at its test re-test reliability and validity.
Correspondence to: Professor R. Sanson-Fisher, De- partment of Behavioural Science in Relation to Medicine, Faculty of Medicine, University of Newcas- tle, Shortland NSW 2308.