This review concluded that a small body of research suggests a range of models may hold potential for improving the health and health care of individuals with mental and addictive disorders, at a relatively modest cost, but further research is needed. Given the evidence presented, the authors' cautious conclusions would seem appropriate; however, the possibility of publication bias cannot be discounted.

To review interventions designed to improve general medical care in individuals with mental and addictive disorders.

MEDLINE, EMBASE, CINAHL, PsycINFO, Social Science Abstracts and the Cochrane Library were searched from inception to June 2005; the search terms were stated. No language restrictions were applied. In addition, the bibliographies of identified papers were checked for further relevant studies and authors were contacted.

Study designs of evaluations included in the review

Randomised controlled trials (RCTs), controlled clinical trials, controlled before-and-after studies and interrupted time series appear to have been eligible for inclusion.

Specific interventions included in the review

Studies examining interventions that explicitly addressed the goal of improving quality of primary medical care were eligible for inclusion. Studies assessing the impact of depression care on medical outcomes such as diabetes and coronary artery disease were excluded. The interventions included in the review varied between studies but included on-site primary care providers, nurses, nurse practitioners, or others delivering various evaluations, care programmes or counselling. The duration of the intervention varied from 2 to 24 months across studies. The interventions were compared with usual care.

Participants included in the review

Studies of individuals with addictive disorders (alcohol and illicit substance use) and/or mental conditions were eligible for inclusion. The participants in the included studies were: adults in a methadone clinic with either hypertension, PPD-positive status, HIV-positive status or acute sexually transmitted disease, and without a primary carer; veterans with alcohol dependence and alcoholism-related medical illness; veterans with serious mental disorders; adults with alcohol and other addictive disorders; adults in an in-patient unit for alcohol, heroin or cocaine detoxification; and adult psychiatric in-patients.

Outcomes assessed in the review

The outcomes included in the review were linkage with primary care (defined as one or more visits with a general medical provider), quality of primary care (medical care delivery consistent with evidence-based guidelines), medical outcomes (change in health status/and or mortality), mental health and addictive outcomes (abstinence or symptom measures), and total costs from the perspective of the health care system.

How were decisions on the relevance of primary studies made?

Two assessors independently selected studies for inclusion.

Validity was assessed using the Jadad criteria, which assess randomisation, handling of withdrawals and drop-outs, and blinding. The authors did not state how the validity assessment was performed.

Two assessors independently extracted the data into a standardized form. Where sufficient data were available, standardised estimates of effect were calculated, using Cohen's d for continuous variables and relative risks for dichotomous variables.

How were the studies combined?

The studies were grouped by outcome and combined in a narrative.

How were differences between studies investigated?

Differences between the studies were apparent in the tables and discussed in the text.

Six RCTS (n=1,477) were included in the review.

All studies were of adequate methodological quality.

Five of the 6 studies found a statistically significant improvement in primary care linkage in the intervention group.

Measures of quality of care varied across studies, but all 4 studies that reported medical quality found a significant improvement in quality in the intervention group relative to the control group.

Three studies investigated abstinence rates: two found no significant differences between the study groups overall, and one found an increase in alcohol abstinence associated with the intervention group compared with the control.

Further medical outcomes were reported for individual studies.

Three studies that formally assessed costs found the programmes to be cost-neutral from a health-plan perspective.

A small body of research suggests that a range of models may hold potential for improving the health and health care of individuals with mental and addictive disorders, at a relatively modest cost. Further research is needed.

The authors set out a clear objective and inclusion criteria were defined for the participants and interventions; those for study design were unclear. Several relevant sources were searched without language restrictions, which helps ensure that relevant studies are not missed and also reduces the risk of language bias. The authors do not appear to have made attempts to identify unpublished studies, and publication bias was not assessed. Efforts were made to reduce the risk of error and bias in the study selection and data extraction processes; however, it is not clear whether the same measures were taken in the assessment of validity. Study validity was assessed using appropriate criteria, but details of the individual assessments were not reported.

Details of individual study data and characteristics were presented. In view of the differences between the studies in terms of populations, interventions and outcomes, a narrative synthesis was appropriate. The authors' cautious conclusions seems appropriate given the evidence presented; however, the possibility of publication bias cannot be discounted.

Practice: The authors stated that for mental health providers to take on more responsibility for their patients' medical care, they will need adequate training and time to allow them to take on these tasks, and appropriate expectations of the types of services that they can safely deliver. The authors suggested that facilitated referrals to primary care may be a practical approach for improving general medical care in freestanding mental health and substance abuse clinics. In addition, it is important that there are adequate primary care resources in the community, formal referral mechanisms, and strategies for communication and information sharing to ensure access to, and coordination with, primary care providers.

Research: The authors stated that future work should continue to develop and test approaches for improving general medical care for individuals with mental and addictive disorders that can be tailored to local system needs and capacities. Furthermore, they suggested that it is important that future research uses standardised measures of quality, health status and intervention characteristics, such as the degree of functional integration of care, in order to allow the pooling of data across studies.

National Institute of Mental Health, grant number MH070437.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.