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7.1.4 Recruitment to the study
In the event, it was possible to recruit 230 consecutive new attenders for treatment of heroin or alcohol dependence who were prepared to give their consent to be followed up, who were not overtly intoxicated at the time of first attendance nor showing signs of active psychiatric illness and who had a primary problem of alcohol or heroin dependence or misuse. The total number recruited constituted 34% of the total number of patients seen for initial assessment for heroin and alcohol misuse and dependence at the base unit during the study recruitment year. The recruitment period was of five months duration and the potential sample size for recruitment during this time was 282 individuals (based upon the estimate of the number of heroin and alcohol patients seen at the base unit over a five month period during the study recruitment year). Of this potential number, 81.6% were recruited into the study. The remainder were not recruited to the study for reasons of intoxication, current psychiatric illness or, in only one case, refusal to participate in follow-up.
The source of the referrals of patients seen for the study was typical of agency referrals, all were new referrals, defined as those who have not been seen at the agency during the past six months. The sample therefore included people who had never been seen at the agency; none of the study participants had received treatment for their substance misuse at this specialist agency during the previous six months. Some of them may have received a substitute prescription from the general practitioner, attended a voluntary agency or self-help group for people wishing to become or remain abstinent.
Of the 230 participants recruited to the study, 65.7% participated in the three month follow-up and a total of 83% were accounted for. At the twelve month follow-up point, 60.4% participated in follow-up and 81.7% of the original sample were accounted for. Of the original sample, 44% (101 individuals) were followed up at both three months and at twelve months.
7.2 Data Collection Procedures
In the discussion on enhancing the validity of self-report data (see Chapter 2 on measuring dependence), a table was presented (adapted from Babor et al. 1987b) listing procedures for minimising response bias and enhancing validity. Methods used in the present study are described in this section.
Once I had identified potential study recruits, they were approached either by me or a research assistant (Roger Brearley), and asked for their consent to take part. All participants who agreed to complete the questionnaire battery and the brief interview and to be followed up twice for
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