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study was designed to examine the nature of change in dependence on a main substance. If participants had changed the main substance upon which they were dependent during the follow-up period, they would be excluded from the analysis for the simple reason that quantity of use data would not be comparable. In the event only one set of responses could not be used in the analysis for this reason.
7.3.2 The method of follow-up at three months and at twelve months
Two weeks in advance of the (first) three month follow-up point, a letter was sent to each study participant reminding them that they had agreed to follow-up and explaining the purpose of follow-up. The option of a domiciliary visit, an appointment at the treatment agency or at a venue of their choice was offered. Study participants were requested to confirm their ability to attend the follow-up interview. This, in the event was not used to deter visits as it was quickly found to be an unreliable indicator of whether the person was expecting to be visited. Equally study participants who did go to the trouble of suggesting alternative venues did not always adhere to the suggestion they had made. In the absence of any response from the participant, a visit was made to the home address they had given.
If study participants were not contacted at the first visit then the information given on the consent form regarding a third party was pursued. If this did not yield a result, the clinical database was examined to see whether the person was currently in treatment. If they were, then the person was contacted during the clinical visit. This was a less than optimal arrangement from the point of view of gaining accurate information on current drug use even though the information was requested by the researcher, not the clinical staff. If this method failed to yield a result then the given address was checked with the original referral source and the questionnaires and a front sheet enquiring about recent use were sent by post once again with a request to return them. No further efforts were able to be made given the available resources.
Records were kept of information gathered on the whereabouts of study participants who were not contacted for follow-up. This information was from friends, neighbours, general practitioners where these were the source of referral, community records of deaths and agency records.
A summary of the follow-up steps, referred to as three levels of follow-up is given below:
1 Follow-up letter sent; appointment at venue to be agreed with study participant. If
confirmed, or if no contact, home visit carried out as suggested in the letter.
2 If not found, contact was attempted with the informant given in the consent form. If
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