Studies of prevention or treatment must meet these additional criteria:

• Random allocation of participants to comparison groups

• Follow up (end point assessment) of at least 80% of those entering the investigation

• Outcome measure of known or probable clinical importance

• Analysis consistent with study design.

Studies of diagnosis must meet these additional criteria:

• Clearly identified comparison groups, at least one of which is free of the disorder of derangement of interest

• Interpretation of diagnostic standard without knowledge of test result

• Interpretation of test without knowledge of diagnostic standard result

• Diagnostic (gold) standard (eg, diagnosis according to Diagnostic and Statistical Manual of Mental Disorders, 4^th edition or International Classification of Diseases, 10^th revision criteria after assessment by clinically qualified interviewer) preferably with documentation of reproducible criteria for subjectively interpreted diagnostic standard (eg, report of statistically significant measure of agreement among observers)

• Analysis consistent with study design.

Studies of prognosis must meet these additional criteria

• Inception cohort (first onset or assembled at a uniform point in the development of the disease) of individuals, all initially free of the outcome of interest

• Follow up of at least 80% of patients until the occurrence of a major study end point or to the end of the study

• Analysis consistent with study design.

Studies of causation must meet these additional criteria:

• Clearly identified comparison group for those at risk of, or having, the outcome of interest (ie, randomised controlled trial, quasi-randomised controlled trial, non-randomised controlled trial, cohort analytic study with case by case matching or statistical adjustment to create comparable groups, case control study)

• Masking of observers of outcomes to exposures (this criterion is assumed to be met if the outcome is objective); observers of exposures masked to outcomes for case control studies; or masking of subjects to exposure for all other study designs

• Analysis consistent with study design.

Studies of quality improvement and continuing education must meet these additional criteria:

• Random allocation of participants or units to comparison groups

• Follow up of at least 80% of participants

• Outcome measure of known or probable clinical or educational importance

• Analysis consistent with design.

Studies of economics of healthcare programmes or interventions must meet these additional criteria:

• The economic question addressed must be based on comparison of alternative diagnostic or therapeutic services or quality improvement strategies

• Activities must be compared on the basis of the outcomes produced (effectiveness) and resources consumed (costs)

• Evidence of effectiveness must be from a study (or studies) that meets the journal criteria for diagnosis, treatment, quality improvement, or a review article

• Results should be presented in terms of the incremental or additional costs and outcomes of one intervention over another

• Where there is uncertainty in the estimates or imprecision in the measurement, a sensitivity analysis should be done.

Review articles must meet these additional criteria:

• An identifiable description of the methods indicating the sources and methods for searching articles

• Statement of the clinical topic and the inclusion and exclusion criteria for selecting articles for detailed review

• At least one article included in the review must meet the above noted criteria for treatment, diagnosis, prognosis, causation, quality improvement, or the economics of healthcare programmes.

Evidence-Based Mental Health has 3 related journals; Evidence-Based Medicine, ACP Journal Club, and Evidence-Based Nursing. Abstracts in their entirety, or a modification thereof, may appear in this journal and a footnote indicating this will appear with each piece. This arrangement increases the number of journals that are regularly searched.

Each article is reviewed by an expert in the content area covered by the article and a commentary is added to provide context of the article in the research that has preceded it; to provide any important methodological problems that affect interpretation; and to provide recommendations for clinical application. The author of the article is given an opportunity to review the abstract and commentary before publication. If there is not enough space to accommodate abstracts for all articles that meet review criteria, citations for the extra articles will be noted in the section of the journal titled Other Articles Noted.