Manual for the Benzodiazepine Dependence Questionnaire (BDEPQ)
Manual for the Benzodiazepine Dependence Questionnaire (BDEPQ)
Manual for the Benzodiazepine Dependence Questionnaire (BDEPQ)
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VALIDITY OF THE <strong>BDEPQ</strong> 43<br />
could not be carried out with <strong>the</strong> same number of predictors used in <strong>the</strong> o<strong>the</strong>r<br />
analyses of <strong>the</strong> predictive validity of <strong>the</strong> <strong>BDEPQ</strong>. Instead predictors of BZD dose<br />
at wave two ra<strong>the</strong>r than change in BZD dose were examined.<br />
The correlation between <strong>BDEPQ</strong> scores at wave one and diazepam-equivalent<br />
dose at wave two was 0:242 (n =177�p < :05) indicating a small relationship.<br />
A regression equation including demographic characteristics (age and sex), use of<br />
o<strong>the</strong>r drugs (tobacco and alcohol), scores on <strong>the</strong> <strong>BDEPQ</strong> and o<strong>the</strong>r questionnaires,<br />
BWSQ scores, and patterns of BZD use (dose, frequency and duration of use, and<br />
half-life) accounted <strong>for</strong> 54:2% of variance in dose of BZDs taken at wave two<br />
(R 2 =0:542�F14�127 =10:753�p < :05). Partial correlation analysis revealed that<br />
dose of BZDs, frequency of BZD use and duration of BZD use <strong>for</strong>m wave onewere<br />
signi cant independent predictors of dose at wave two. <strong>BDEPQ</strong> scores did not<br />
independently predict dose at wave two indicating that <strong>the</strong> correlation of 0:242<br />
reported above is shared with o<strong>the</strong>r variables.<br />
The <strong>BDEPQ</strong> as a screening test <strong>for</strong> diagnoses of dependence<br />
So far BZD dependence has been considered as a continuum. There are many<br />
instances were interpretation of a test is made easier by cut-o scores. It is easier<br />
<strong>for</strong> test users to make a categorical statement from test scores than it is to consider<br />
<strong>the</strong> respondent on a dimension. For this reason alone I analysed <strong>the</strong> ability of <strong>the</strong><br />
<strong>BDEPQ</strong> to act as a screening test <strong>for</strong> diagnoses of BZD dependence made using<br />
<strong>the</strong> CIDI. For this analysis it is assumed that CIDI diagnoses of dependence are<br />
<strong>the</strong> `Gold Standard' even though this proposition has been disputed above.<br />
A Receiver Operating Characteristic (ROC) curve was plotted from <strong>the</strong> sensitivity<br />
and false alarm rate by treating each score on <strong>the</strong> <strong>BDEPQ</strong> as a cut-o point.<br />
Sixty-eight participants had complete in<strong>for</strong>mation on both <strong>the</strong> <strong>BDEPQ</strong> and <strong>the</strong><br />
CIDI. Of <strong>the</strong>se 68, 21 (30:9%) had ei<strong>the</strong>r a current CIDI diagnosis of DSM3R or<br />
ICD10 BZD dependence or had met criteria <strong>for</strong> such a diagnosis at some time in<br />
<strong>the</strong> past. ROC analysis has two objectives: selecting an optimal cut-o score, and<br />
testing whe<strong>the</strong>r <strong>the</strong> screening test predicts <strong>the</strong> `gold standard' better than chance.<br />
Figure 2 shows a graph of <strong>the</strong> ROC curve <strong>for</strong> <strong>the</strong> <strong>BDEPQ</strong>. The obtained<br />
sensitivity and false alarm rates (1 - speci city) are shown as points. A natural<br />
logarithm function has been tted to this obtained data. Selected points are<br />
labeled with <strong>the</strong> <strong>BDEPQ</strong> scores <strong>the</strong>y re ect. A diagonal line has also been plotted<br />
to repented <strong>the</strong> screening pro le of a random or chance test. Points on <strong>the</strong><br />
<strong>BDEPQ</strong> ROC curve far<strong>the</strong>st from this line are better cutting points. Two cutting<br />
points emerge from inspection of Figure 2, <strong>the</strong>se are scores of 23 and 34. The<br />
choice between <strong>the</strong>se points depends on <strong>the</strong> relative importance of <strong>the</strong> correctly<br />
identifying people who are BZD dependent compared with <strong>the</strong> costs of falsely<br />
selecting people who <strong>the</strong> CIDI would not diagnoses as BZD dependent. If correctly<br />
identifying BZD dependence was of greater importance a cutting score of