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8.3 Sample 6b: questionnaire and interview results at t1
Of the 230 study participants, a total of 188 (81.7%) were traced at twelve months. Of these, 139 participated in follow-up but data were analysed for only 138 of them because one participant had changed his primary substance from heroin to alcohol. For the purpose of the present study it was not appropriate to include t3 data for this participant in the analyses which included the twelve month follow-up data. Of the 139 individuals who were followed up at twelve months, 37 had not been followed up at three months. Of the 138 individuals for whom data were collected at twelve months, the sample referred to as Sample 6b, 87 (63%) were primary heroin users and 51 (37%) were primary alcohol users. Thus the proportion of heroin users to alcohol users in the sample followed up at t2 and the sample followed up at t3 were similar. One hundred and two (73.9%) were men and 36 (26.1%) were women. Thus 75% of the original sample of women were seen at twelve months whereas 56% of the original sample of men were seen and the difference between these proportions was significant. Mean age of the twelve month follow-up sample was 30.6 (SD = 11.8) and the range was 15 to 80 (see Table 8.4). Mean age of the heroin group was 24.3 (SD = 5.8) and the range was 15 - 47. Mean age of the alcohol group was 41.3 (SD = 11.6) and the range was 20 - 80.
8.3.1 Comparisons between Sample 6b and the group not seen at twelve months: questionnaire and interview results at t1
Data collected at t1 are presented for the sample seen at t3 (Sample 6b) and the group not seen at t3 (see Table 8.8). Of the 151 study participants who participated in follow-up at three months (t2), 49 were not seen at twelve months (t3) and data collected at the time for one participant was not used in the analysis, as described above. Data collected at t1 are therefore presented in Table 8.8 for 92 individuals not seen at t3. Forty-two individuals did not participate in follow-up either at t2 or at t3.
There was a larger ratio of alcohol users to heroin users and women to men in the sample seen at twelve months compared to the group not seen at twelve months. There is a significant difference in the proportion of women in the sample seen at t3 (26.1%) and the proportion of women in the group not seen at t3 (13%). Of the original sample of women, those in Sample 6, 73% were seen at three months and 75% were seen at twelve months (see Table 8.4). The greater proportion of men in the group not seen at t3 compared to the sample seen at t3 did not reach
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