Study Setting and Research Design

II. METHODOLOGY

II.1. Study Setting and Research Design

The study was conducted at a community drug and alcohol service in Greater London. The service operated from a harm minimisation model and hence focused on minimising the negative outcomes of continued substance misuse. It thereby aimed to address the conditions and context of substance use while addressing drug use itself. The team at the service was multidisciplinary, consisting of trained

non-medical drug and alcohol workers (keyworker), nurses, psychologists, physicians and psychiatrists.

The service provided clinical interventions such as substitute prescribing services or access to in-patient services. It incorporated a spectrum of strategies, ranging from a full assessment of treatment needs for drug and alcohol users, individual support, psychological counselling, psychotherapy, assessment for funding for detoxification and rehabilitation programmes, alternative therapies (for example, auricular acupuncture, shiatsu) and referral to other services. It also offered information and testing to clients on blood borne viruses like HIV and hepatitis, as well as sexual health advice. Referrals were accepted from any source including self-referrals and referrals from family members.

The project leaders were a clinical psychologist and the aforementioned doctorate student. The CM programme was designed within the general requirements and principles that were set out by the NTA. The following will attempt to outline the contributions of the researchers to the pre-existing design features from the NTA.

The target behaviour (abstinence from crack cocaine), the selection of the eligibility criterion (a minimum of twice weekly self-reported crack use), the voucher value and scaling of the incentives was defined by the researchers. For example, the magnitude of the reinforcement vouchers; starting with a monetary value of £5, rather than £2 as the NTA proposed, and increasing by increments of £5 to a maximum of £20. So was the decision to use vouchers from the retailers; Argos, Boots, JJB Sports, MK One, Shoe Express, Virgin Megastores, WH Smith and Woolworths. The specifications of these CM protocol features were achieved in discussions with the clinical psychologist and the doctorate student, and negotiations with the NTA.

The incentive schedule was outlined by the NTA, so was the rule of ‘resetting’ the value of the incentive at the next appointment to the starting level if non-compliance occurred. Also, the recommended length of the programme was 12 weeks. The budget was calculated by Dr. Christo on the basis of the results of the random urine checks from the opiate maintenance clients that were on the caseload at the service, for more details please see section; III.3.3. Changes in the Planned Data Analyses.

Equally, the costs for the two research assistants were estimated and included in the budget.

Regarding the staff training at the service; the project development was supported by the NTA with a template PowerPoint presentation and trainer’s notes. These resources were used by the clinical psychologist to train the staff at our service.

Teaching of the material was spread over two conventional weekly team meetings.

The two training events consisted of a mixture of didactic and participatory learning.

Specific topics and clinical issues were addressed through role-play exercises, with theoretical background lectures as necessary. Drug and alcohol workers and two research assistants supported the implementation. Dr. Christo and myself attended the training session at the NTA.

Monitoring of the data collection process and a minimum of weekly consultations with the research assistants were undertaken by myself. Additionally, the doctorate student performed data processing into Excel and SPSS spreadsheets, and the evaluation of the study independently and autonomously. The anonymised data set was supplied to the NTA, at several timepoints. Additionally, the doctorate student presented the results of the investigation at an NTA workshop in 2009.

A quasi-experimental design with a convenience sampling method was employed to monitor client’s frequency of crack cocaine use. Clients on opiate maintenance that fulfilled the eligibility criteria (please see section; II.2 Participants) were asked if they were interested to participate in the CM programme. From this group of clients, a sample of clients agreed to participate and attended the scheduled reinforcement sessions. The remainder of clients agreed to participate but did not engage with the intervention. As a result, a natural unplanned comparison group (Standard treatment group; ST) developed from participants that initially agreed to participate in the CM intervention but did not attend any of the scheduled reinforcement sessions. These clients continued to receive standard treatment, including opiate maintenance treatment and key working.

The central tenets of the intervention in the CM group were to (a) urine test clients at fixed intervals according to a standardised incentive protocol in a 12-weeks

intervention period (for the incentive protocol, please see section; II.4.2. Contingency Management Group), (b) provide monetary based incentives when cocaine abstinence was demonstrated, (c) withhold the incentive when cocaine use was detected. The incentive consisted of monetary based vouchers. Participants can earn a maximum of £240 in vouchers if they submit all 21 scheduled negative specimens.

Two dependent outcome measures were employed; self-reported crack cocaine consumption (verified by a minimum of fortnightly urine analysis) and quantitative urinalysis results.

The first part examined between-treatment group differences in the standard treatment and the voucher CM condition. The primary dependent measure was self-reported crack cocaine use (responses extracted from the TOP questionnaire) at three time-points; at baseline (a four week period) – timepoint 1, 3 months + 1 week (i.e., on average 1 week after the CM programme intervention concluded) – timepoint 2, and at 6 months follow up (on average) – timepoint 3. We also explored the remaining relevant responses from the TOP and CISS questionnaire.

The second part investigated within-group differences in the voucher CM group. The primary dependent outcome measure was crack cocaine abstinence measured by objective urinalysis results over the 12-weeks intervention period (for the incentive schedule, please see section II.4.2. Contingency Management Group), and responses from timepoint 1.

The following measures of control were employed:

1. Researchers were trained by the NTA and the research assistants were trained by one of the researchers, to assure accurate and reliable application of the CM protocol with clients.

2. Researchers monitored study procedures weekly to ensure appropriate conduct.

II.2 Participants

Participants were 42 outpatients receiving opiate substitution treatment between February and August 2008. Participants were eligible for the study if they had been enrolled with the NHS service, provided objective evidence of current opiate dependence and at least 1 year of opiate use and had been stabilised on an opiate substitute (i.e. methadone or buprenorphine) dose for at least 1 month. They also provided objective evidence of cocaine use and reported smoking crack cocaine a minimum of twice⁶ a week, were 21 years or older (the minimum required age at the service for opiate substitution treatment was 21 years), and spoke English. Except where otherwise indicated, the term cocaine misuse is used in this study in a generic sense and not according to the Diagnostic and Statistical Manual of Mental Disorders (4^th ed.; American Psychiatric Association, 1994).

Participants were excluded from the study if they were unable to comprehend it, had a psychotic disorder (schizophrenia, bipolar disorder) that was not adequately controlled by medication, were currently suicidal or were affected by serious unstable medical illnesses. Further, clients who already participated in another research project were also excluded. Study criteria were not restrictive to increase generalisation of findings. Participation in the research project was voluntary, informed consent was obtained and confidentiality of the responses was assured by anonymising the data. For more details please see section, II.7. Ethical Considerations and Consent.

A convenience sampling method was employed. Research assistants and drug and alcohol workers presented and discussed the study with 49 clients. Those not consented stated that they were not interested to participate in the study (n = 4), or did not meet the study criteria (n = 3). Twenty-one (50%) clients agreed to participate in the contingency management group and started to attend scheduled reinforcement sessions. A further twenty-one (50%) clients initially agreed to participate in the CM group but did not attend any of the scheduled reinforcement sessions. It was spontaneously decided that this group of clients could function as a

6 Crack cocaine is often taken repeatedly over a period of time that may last hours or days, called a

comparison group (standard treatment group). Clearly, the nature of this group and the non-randomisation of the participants carry certain implications in terms of the conclusions that can be drawn from the study, please see section, IV. Discussion.

Inspection of the data revealed that the 7 excluded patients were similar to the 42 patients who represented the final sample, in terms of years of heroin and cocaine use, demographics, previous drug treatment attempts and opiate substitution dose (for more details regarding the final sample please see section, III.4. Demographic and Baseline Characteristic section, Table 1).

Representativeness of the sample was examined by pertaining to the statistics from the National Drug Treatment Monitoring System (NDTMS: Annual Report, 2008/09), regarding the following client characteristics; age, gender and ethnicity.

First, the average age for the CM group was 42 years (SD = 10) and 42 years (SD = 7) for the standard treatment group, this is comparable to the average age of 44 of opiate and crack cocaine users in the NDTMS report. Second, the NDTMS report did not provide any data on opiate and crack cocaine users in London compiled by gender. However, 30% of all clients seeking treatment in drug and alcohol services in London were female. This number was slightly higher in the CM group 48% (female participants) and slightly lower 24% (female participants) in the ST group. Third, according to the NDTMS report, 67% of all clients’ seeking treatment for drug and alcohol problems in London reported to be White and 33% belonged to other ethnic groups (i.e., ‘Mixed’, ‘Asian British’, ‘Black British’, ‘Other Ethnicity’ and ‘Not stated’). This was comparable to 76% and 86% of clients who reported to belong to a White ethnic group in the CM and standard treatment group, respectively. Moreover, the distribution of ethnicity was representative of the General Population census in London (2001) where 72% reported to be White British and 28% belonged to other ethnic groups. Equally, the distribution of ethnicity was representative of the population served by this Trust (Dr. N. Margerison, personal communication; April 2008).