Application of the public health model to intervention research is an essential ingredient differentiating clinical trials that test the efficacy of a treatment within a carefully chosen set of patients from studies of intervention effectiveness in more representative samples. Treatments that are found efficacious in controlled settings may lack effectiveness for a variety of reasons, many deriving from characteristics of the patient as well as factors about the clinician. Of particular relevance to PROSPECT, Inhibitors,research,lifescience,medical patient volunteers are likely to differ from

patients who do not volunteer by the severity of depression, coexisting medical illness, or functional disability, or attitudes and beliefs about mental health problems and their treatments, all factors that have been shown to also affect treatment initiation, adherence, and response53,54 – that is, the Inhibitors,research,lifescience,medical likelihood that a patient might benefit from the intervention PROSPECT offers. These patient selector factors may also affect primary care physician behavior. For example, patients with comorbid medical illness can pose greater difficulties in diagnosing

depression, be less willing to acknowledge or discuss depressive symptoms, impose greater constraints on physician time. There is also a tendency for clinicians to undervalue the severity of depression and its impact Inhibitors,research,lifescience,medical on quality of life in older age. Finally, there may be problems in diagnosis associated with cognitive decline and medical comorbidity, and patient and family unwillingness to be treated or to adhere to treatment. To obtain its representative sample, PROSPECT uses a stratified, 2-stage design aimed to include an oversample of very Inhibitors,research,lifescience,medical old subjects (over 75 years) as well as a disproportion al number of patients with depressive symptoms. The key is being

able to generalize back to the full practice population. A small number of patients without depressive symptoms are entered into the study both to accommodate the possibility of false negatives inherent in Inhibitors,research,lifescience,medical any screen and to investigate the intervention’s effect on prevention and early detection of depression. The sampling frame employed by PROSPECT is the weekly appointment system. PROSPECT investigators decided to select a sample of patients with scheduled upcoming appointments because this is the group for whom identification those and treatment is most relevant in a primary care practice. Depression in patients who do not visit their doctors will not, by virtue of their absence, come to the attention of primary care physicians. The sampling frame also omits patients who make urgent Selleck JSH-23 visits to the practice on the rationale that intervention activities are not designed for use during emergency care, so that patients who show up for unscheduled visits are not appropriate for inclusion into the study at that time.