The CASPER trial: Can collaborative care to prevent and treat depression among older adults in primary care?
A portion of older people experience lower severity depression, often in association with long term health problems. This group of people are often identified through screening and case finding where they ‘screen positive’ but do not meet conventional treatment thresholds for clinical depression. Older people with subthreshold depression are nonetheless impaired and consume high levels of healthcare resources. This is an important group of people who are at risk of developing more severe illness, but for whom there is little that is offered at present. Collaborative care incorporating brief psychological therapy is one potentially effective intervention but there are no UK trials. The NIHR Health Technology Assessment Programme commissioned such a trial to address this evidential gap. We present the initial results of the Collaborative Care for Screen-positive Elders (CASPER trial ISRCTN02202951).
We conducted a large scale pragmatic three arm trial of 705 adults aged 65+ who had depressive symptoms (and screened-positive on the ‘Whooley questions’) but did not reach the threshold for DSM-IV Major Depressive Disorder (‘screen-positive subthreshold depression’). Intervention participants were randomised to either collaborative care with provision of evidence-supported psychological therapy (behavioural activation) or usual GP care alone (control condition). The primary outcome was depression severity (PHQ9) at four months post-randomisation. Secondary outcomes included the onset of case-level depression, anxiety (GAD7) health-related quality of life as measured by the SF- 36 at four and 12 months.
The primary endpoint at four months favoured Collaborative Care (mean difference: 1.31 PHQ-9 score points, 95% CI: 0.67 to 1.95, p<.001, standard effect size = 0.30). Treatment differences were maintained at twelve months follow-up (p=.001). Case-level depression was reduced in the collaborative care group compared to usual care at 12 months (Odds Ratio 1.98, 95%CI 1.21 to 3.25, p=.007). Secondary outcomes at four and twelve months follow-up also favoured collaborative care, including: improved SF-12 physical functioning (p<.001 and p=.020 at each respective time point) and reduced GAD-7 psychological anxiety (p<.001 and p=.001).
There is relatively little research to inform the provision of care for older adults with low severity depression. The results of the CASPER trial show that collaborative care is effective across a range of outcomes in this group and that the benefits are sustained at 12 months. This represents a non-pharmacological treatment option that could be offered in primary care with the potential to prevent the onset of more severe disorders.