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claim to be free of the influence of different socio-economic groups, it was tested in New Zealand populations of white people of European descent, Pacific Islanders and Maori (personal communication with Grant Paton-Simpson), where it was found to be acceptable for use by these various ethnic and cultural groups. It has been adopted for routine use in New Zealand government funded agencies as a result.
3.5 Criteria for the comparison and evaluation of scales designed to measure dependence
Not all of the available scales designed for the measurement of dependence have been described in this chapter; those that are described were selected on the grounds that they were presented in self completion format, were developed for use and validated in clinical or help-seeking populations and measured one or both of the main study substances, alcohol and heroin. This selection was based upon the requirements of the present study: self completion questionnaire format is not only the most widely used but is arguably the most appropriate for routine clinical use. The purpose in attempting to elucidate the nature of change in dependence was one of clinical utility and the chosen context is one that combines alcohol and heroin dependence. Five criteria for the development of a scale appropriate for use in such a context were identified by Raistrick et al. (1983) in their development of the SADD and subsequently by Raistrick et al. (1994) in their development of the LDQ. These criteria are elaborated below for the purpose of offering a critical comparison of the utility of the scales described in this chapter.
The proposed criteria can be organised under a number of headings: suitability for routine clinical use would include brevity, readability, neutrality; suitability for routine clinical use would include the ability to measure substance (not specified) dependence (though this might not be a universally agreed criterion as many services remain substance specific, it is nonetheless an advantage for comparing severity of dependence across substances), to measure the entire range of dependence and to measure change. This refers both to the question about whether the time frame allows for change or refers to lifetime dependence, as well as the ability of the scale to measure dependence in abstinence. Finally, although it might be considered to be part of the validation of a scale, the question of whether the scale is theory-based and the items theory-derived merits further attention.
All these criteria were addressed in the development of the LDQ and subsequent validation studies would suggest that the criteria have been met, though there remains a question about the adequacy of the response choices and whether the items measuring the maximisation of the effect of
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