Effects of training community staff in interventions for substance misuse in dual diagnosis patients with psychosis (COMO study): Cluster randomised  trial

A cluster randomised controlled trial was used to investigatethe effectiveness of training staff in 13 London communitymental health teams (CMHTs) to deliver substance misuse interventionsto patients with psychosis and comorbid substance misuse (‘dualdiagnosis’). The primary hypotheses, which were thatexperimental group patients would spend fewer daysin hospitalover 18 months of follow-up and show reduced alcohol and drug consumption, were not confirmed, although confidence intervalswere wide for some outcomes. Current UK policy guidance advocatestraining CMHT professionals to deliver dual diagnosis interventions,but the effectiveness of this strategy has not so far beendemonstrated.

INTRODUCTION

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INTRODUCTION

The adverse outcomes associated with psychosis and comorbidsubstance misuse (‘dual diagnosis’) have been welldocumented, but treatments supported by substantial evidenceare few (Jeffery et al, 2000; Tyrer & Weaver, 2004). Interventionsthat show some benefit have tended to involve relatively intensivetreatment of selected populations by specialist therapists (Barrowclough et al, 2001;Bellack et al, 2006); generalisability to routine settingsis unknown. However, commentaries and policy guidance on dualdiagnosis in England have favoured ‘mainstreaming’dual diagnosis interventions by integrating them into careprovided by existing clinical teams (Johnson, 1997; Weaver et al, 1999; Department of Health, 2002). The effectiveness of this strategyis untested.

Our aim was to investigate whether a training and supervisionintervention delivered to community mental health team (CMHT)case managers would improve patient outcomes. At the patientlevel, the primary hypotheses were that, compared with controls,patients on the case-loads of experimental group case managerswould make less use of in-patient services and would be consuming smaller quantities of substances when assessed 18 months later.

METHOD

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METHOD

A cluster randomised controlled trial design was employed, eachcluster consisting of the patients on a particular staff member’scase-load.

All permanent case managers in 13 London CMHTs were invitedto participate. Their case-loads were screened for patientswho met study criteria for dual diagnosis, and all who didwere included in the sample. This screening stage involvedfirst identifying patients with clinical diagnoses of schizophrenia, another non-affective functional psychosis, or bipolar affectivedisorder. With guidance from researchers, case managers ratedeach of these patients using the Clinician Alcohol and DrugUse Scales (Drake et al, 1996). Patients identified as misusingor dependent on at least one substance met our study criteriafor dual diagnosis. Case managers were randomised to interventionor control groups by an independent statistician. All patients identified as eligible for the trial entered the experimentalor control group according to their case manager’s assignment.

The experimental intervention consisted of a treatment manual,a 5-day training course in assessment and management of dualdiagnosis, and subsequent monthly supervision. Motivationalinterviewing was a central source (Swanson et al, 1999), andthe training also drew on cognitive–behavioural relapseprevention techniques (Irvin et al, 1999). The control groupreceived CMHT management as usual with no specific dual diagnosisintervention. To reduce contamination, experimental group staffwere asked to avoid sharing manuals and details of training.

At baseline, socio-demographic and clinical details of all patientswere recorded. At baseline and after 18 months, data were collectedon the two primary outcome measures: (a) hospital bed use overthe preceding 18 months, recorded using best available informationfrom patient interview, clinical records and local electronicpatient data systems; (b) substance use over the precedingmonth, documented at patient interview using the Maudsley Addictions Profile (Marsden et al, 1998).

Secondary outcomes relating to adverse events, symptoms andsocial functioning and staff-level outcomes were also assessed,but are not reported here. Interviews with patients were carriedout whenever possible; for patients who were not available,ethical approval was obtained to gather data from staff ontheir characteristics and the bed use outcome.

RESULTS

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RESULTS

Seventy-nine case managers participated. Of the 1560 patientson their case-loads, 232 met criteria for dual diagnosis. Fortyof the 79 case managers were randomised to the experimentalgroup and 39 to the control group. This yielded 127 patientswith dual diagnosis on case-loads of case managers in the experimentalgroup and 105 on control group case-loads. Miles et al (2003)have described the characteristics of the sample. Experimentaland control groups were similar except for an imbalance forWhite ethnic group (61% of the control group v. 43% of theintervention group). CONSORT diagrams of staff and patientflows through the study are given in data supplement 1 to theonline version of this paper.

Three patients died during the 18-month follow-up period. Ofthe remaining 229 patients, 77 (62%) of the intervention groupand 77 of the control group (74%) were interviewed at follow-up(P=0.079). Bed use data were obtained for 113 interventionand 97 control group members. We defined experimental grouppatients as having received the intervention as intended if their case managers had attended at least 4 days of trainingand if they had remained on the case-load of a trained casemanager for at least 9 months: just 45 of the 127 experimentalgroup patients met these criteria. Eighty-six of the 105 controlgroup members fitted the study definition of having remainedin their intended treatment group, which required them to have remained on a CMHT case-load for at least 9 months and notto have been taken on by a trained case manager.

Details of outcomes are shown in data supplement 2 to the onlineversion of this paper. For bed use, there was no evidence ofa difference between experimental and control groups (meanbed use for experimental group: 74.9 days (s.d.=142.6) over18 months follow-up; for control group 71.8 days (s.d.=128.1),P=0.30 following log transformation and adjustment for baseline).However, standard deviations were higher than anticipated when carrying out the study power calculations, resulting in wide95% confidence intervals. There was no significant differencein proportion of patients admitted during the follow-up period(43% of the experimental group v. 48% of the control group,P=0.18).

Self-reported alcohol and drug use of interviewed members ofeach group over the 30-day period before the follow-up intervieware also shown in online data supplement 2. Neither the proportionwho had consumed substances (74% of the experimental groupand 71% of the control group for alcohol, 32% and 36% respectivelyfor cannabis and 16% and 18% for other drugs) nor the quantity consumed over the month differed between groups. No differencein outcomes became significant after adjusting for baselinevalues.

DISCUSSION

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DISCUSSION

The study’s strengths lie in external validity: the interventiontook place in a routine National Health Service setting andwas brief enough to be replicable in such settings, and allidentified patients with dual diagnosis were included. Limitationsinclude high attrition from the intended intervention, relianceon clinician substance misuse diagnosis and lack of masking.Fidelity was not measured, and we do not know to what extentcase managers implemented the intervention as intended. Also,for the main outcomes, standard deviations were wider thananticipated when power was calculated: confidence intervalsare thus wide and include the possibility of a substantialeffect in either direction.

There was no evidence that the training intervention affectedbed use or substance use. The limitations discussed above mustbe considered in interpreting this finding. Also, there ismuch evidence that influencing outcomes among people with dualdiagnosis is difficult, with many reported negative findings(Tyrer & Weaver, 2004). Our intervention was of low intensity,and the limited amount of training provided might have beeninsufficient to influence clinical practice. Our findings thusfail to lend any clear support to the current UK policy of‘mainstreaming’ dual diagnosis interventions bytraining staff within generic mental health services to deliverthem. Other models for introduction of dual diagnosis interventionsinto routine clinical settings may therefore need to be tested,taking into account the few available positive findings fromefficacy studies in more selected groups (Barrowclough et al, 2001;James et al, 2004). Possible options include specialist dualdiagnosis teams and specialist workers within CMHTs. Providinginterventions at an early stage of illness when adaptive andmaladaptive ways of coping with illness are less well establishedhas so far been evaluated only in small pilot studies (Kavanagh et al, 2004;Edwards et al, 2006). Until further evidence is available aboutthe effectiveness of implementing these models in routine settings,evidence-based policy making in the area of dual diagnosisposes great difficulties.

REFERENCES

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