Page 77 - PhD GT

to be satisfactory and factor analysis of all four sections yielded a single major factor which accounted for 39% of the variance with a second factor accounting for only 10% of the variance. Principal components analysis yielded a first factor which accounted for 43% of the variance.
The relationship between the dependence items and the quantity of heroin used in milligrams per day was examined and, with the exception of withdrawal-relief items, correlations were small and non-significant. A small non-significant negative correlation was found between the narrowing of drug taking repertoire question and the total SODQ score but a positive correlation was found between total SODQ score and responses to the question on tolerance and also number of times used in a day. No relationship was found with duration or milestones of use.
In view of the discussion of dependence in the first chapter of the present study, there must be some question as to whether the SODQ measures dependence or whether in fact it mainly measures the consequences of regular use, namely the presence of withdrawal phenomena and the behaviour which is triggered by it. Questions regarding the appropriateness of reinstatement being an element of dependence or a more straightforward learning phenomenon have been raised and it does not therefore seem surprising that the section on reinstatement yielded the findings it did. On the other hand, the proposal that dependence is a psychological phenomenon with physiological sequelae would produce the prediction that higher correlations would be found with number of times per day using (a possible impaired control / perceived inability to abstain item) than with the quantity used and this is what was found in the present study. However, the authors of the SODQ conclude that this was a failure to validate the instrument. In the light of their findings, the authors question whether the construct which they are examining is in fact related to dependence or whether their concept of the nature of dependence “may stand in need of review” (Sutherland et al. 1986 p. 491).
In a subsequent validation study of the SODQ, Phillips et al. (1987) administered the questionnaire and the same additional questions as were administered by Sutherland et al. (1986) to a UK sample of 107 opiate addicts seeking treatment at three treatment units. On this occasion a significant positive correlation was found between total SODQ score and the number of times used per day only with those respondents who were injecting their main drug. No relationship was found with duration of use and only a weak relationship was found with dose. Again no correlation was found with the “narrowing of the drug taking repertoire” item and on this occasion the authors questioned whether this dependence marker, taken directly from the originally described markers of alcohol dependence (Edwards et al. 1977), is as applicable to opiate addicts whose use would not, at one time be so varied as would the use of alcohol by a ‘social drinker’. Simply put, the repertoire of
65