The gains to be made from effectiveness trials are not without costs or challenges. The most relevant and reasonable clinical treatments, including psychosocial therapies, must be identified for testing. Rational treatment algorithms should be developed on the basis of efficacy trials and, where evidence is lacking, expert consensus used to identify relevant comparison treatments. Such consensus might help eliminate the inclusion of inappropriate treatments sometimes used in clinical practice—for example, mega-doses of antipsychotics or off-label use of gabapentin.
Psychosocial interventions need to be appropriate for the level of training and supervision available in typical community settings. Because effectiveness studies use more diverse samples and treatment settings, they will require a larger sample to overcome "noise" and detect treatment effects. Settings as well as a diverse population of providers and patients, who may be naive to research, must be recruited. Also, providers, clinics and administrators must be able to implement a common intervention strategy across sites. Researchers may be unfamiliar with the concerns and needs of community practices. For example, clinical practices may be wary of randomly assigning patients to treatment groups, especially to a placebo treatment group. Thus effective partnerships between research institutions and community practices must be established to share knowledge and staff, incorporating the values and priorities of community partners in the research design.
Relevant outcomes for diverse stakeholders must also be determined by consulting with patients, providers, and policy makers. Finally, because effectiveness trials require large numbers of participants and alternative settings, the costs of these trials far exceed those of smaller efficacy trials, and the mechanisms for funding research and community partners (subcontracting) may be quite cumbersome. A combination of funding streams, from both public and private agencies, is often required. Despite these challenges, the evidence gained from effectiveness trials is critical to promoting high-quality, cost-effective mental health care.