A randomised evaluation of CollAborative care and active surveillance for Screen-Positive EldeRs with sub-threshold depression (CASPER): study protocol for a randomized controlled trial

Background Depression accounts for the greatest burden of disease among all mental health problems, and is expected to become the second-highest amongst all general health problems by 2020. By the age of 75, 1 in 7 older people meet formal diagnostic criteria for depression. Efforts to ameliorate the burden of illness and personal suffering associated with depression in older people have focussed on those with more severe depressive syndromes. Less attention has been paid to those with mild disorders/sub-threshold depressive syndromes but these patients also suffer impairments in their quality of life and level of functioning. Methods/Design The CASPER study has been designed to assemble an epidemiological cohort of people over 75 years of age (the CASPER cohort), from which we will identify those eligible to participate in a trial of collaborative care for sub-threshold depression (the CASPER trial). We aim to undertake a pragmatic randomised controlled multi-centre trial evaluating the effectiveness and cost-effectiveness of collaborative care; a low intensity psychological intervention in addition to usual general practitioner care versus usual general practitioner care alone. General practitioners from practices based in the North of England will be asked to identify potentially eligible patients over the age of 75 years. Patients will be sent a letter inviting them to participate in the study. We aim to recruit approximately 540 participants for the CASPER trial. A diagnostic interview will be carried out to ascertain trial eligibility with the major depressive episode module of the Mini International Neuropsychiatric Interview (M.I.N.I.), eligible participants randomised to either the intervention or usual care. The primary outcome will be measured with the Patient Health Questionnaire-9 (PHQ-9) and additional quality of life measures will be collected. Data will be collected at baseline, 4 and 12 months for both trial and cohort participants.