Wells 2000b.

Methods	Study design: Cluster‐randomised controlled trial
Participants	Setting: Primary care Diagnosis: Depression measured by the Composite International Diagnostic Interview (CIDI) and items assessing depressed symptoms in the past month. Defined patients as having probable disorder if they had 2 weeks or more of depressed mood or loss of interest in pleasurable activities during the last year or persistent depression over the year, plus having at least 1 week of depression in the last 30 days Inclusion criteria: Patients who intended to use the clinic as a source of care for the next 12 months Exclusion criteria: Younger than 18 years, had an acute medical emergency, did not speak English or Spanish, or did not have either insurance or a public‐pay arrangement that covered care delivered by the mental health specialists in the interventions.   In the pilot month for the first site, patients screening positive for bipolar disorder or alcoholism were excluded, but not for the main study Age: Mean 43.7 (SD 15) years Gender: 71% female Ethnicity: 57% white Country: United States Sample size (randomised): 31 primary care clinics, intervention 15, control 16; Total participants 932, intervention 489, control 443
Interventions	Intervention: Quality improvement therapy (QI‐therapy) Contains the four elements of collaborative care: 1) a multi‐professional approach to patient care: Primary care clinicians (PCP), psychotherapist (CM), psychologist (MH specialist) 2) a structured management plan: The programme included 1) institutional commitment, 2) training local leaders to implement interventions 3) training of CMs (patient education and activation based on a written manual and videotape) 4) patient identification. CMs assessed, educated, and activated) patients, sharing the information with PCPs who formulated a treatment plan with the patient. QI‐therapy involved psychotherapists providing manualised individual or group CBT which consisted of 3 modules of 4 sessions with a recommendation for repeating the first one. Patients were provided with a manual for recording clinical progress and homework assignments 3) scheduled patient follow‐ups: 12‐16 individual or group sessions (4 sessions for those with minor depression) 4) enhanced inter‐professional communication: CM used feedback forms to communicate with PCPs at beginning, at termination and at module breaks Control: Treatment as usual enhanced as treatment guidelines, with quick reference guides for clinicians, were sent to medical directors. Patients were told they could inform the PCP of allocation/diagnosis
Outcomes	Depression (Probable depression): 6, 12, 24, 57 months Medication use: 6, 12, 18, 24 months Quality of Life (mental and physical health): 6, 12, 18, 24, 57 months, 9 years
Notes	CBT: cognitive behaviour therapy; CIDI: Composite International Diagnostic Interview; CM: case manager; MH: mental health; PCP: primary care provider
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Clusters were organised into blocks of 3, blocks were randomised using random numbers table
Allocation concealment (selection bias)	Unclear risk	Insufficient information available to assess
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Short‐term loss to follow‐up based on primary depression outcome (Probable depression) was: overall 144/932 (15%), 87/489 (18%) intervention and 57/443 (13%) control. Reasons for loss to follow‐up not provided by group. Used intention‐to‐treat analysis
Selective reporting (reporting bias)	Low risk	Protocol available and all prespecified outcomes reported
Other bias	Unclear risk	Insufficient information available to assess
Implementation Integrity	Unclear risk	Insufficient information available to assess
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants and personnel could not be blinded, outcome likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information available to assess