Multimorbidity is commonly defined as the presence of two or more chronic medical conditions and is associated with reductions in quality of life and functional decline (Wallace et al, 2015). In addition, it is linked to increased healthcare utilisation, which will result in higher costs (Wallace et al, 2015).
Collaborative care, integrated physical and mental healthcare, requires that patients and healthcare professionals from different specialties mutually identify problems and agree goals. In England, collaborative care is recommended for adults with moderate to severe depression and a chronic physical health problem, if symptoms do not respond to initial interventions (NICE 2011).
Literature has generally shown that collaborative care increases health, however, there is limited long-term (>1 year) evidence from trials and the literature has been dominated by US studies with UK evidence limited (Atlantis 2014, Thota 2012, Tully 2015, Gilbody 2006).
The COINCIDE trial evaluated the clinical effectiveness of collaborative care over a short-term period (4 months) and found it to be associated with a significantly greater improvement in depression symptoms compared with usual care (effect size: 0.30) (Coventry et al, 2015).
The article discussed here is based on results from the same trial and expands on the previously published work, reporting the long-term (24 months) clinical and cost-effectiveness of collaborative care for people with depression alongside a long-term physical health condition.
The study used a cluster randomised trial in the North-West of England to compare collaborative care to usual care for depression alongside diabetes and/or coronary heart disease.
Participants were identified from clinical practice database records of patients with diabetes and/or coronary heart disease.
- Patients were screened twice prior to enrolment over two weeks for depressive symptoms (score of ≥10 on the Patient Health Questionnaire; PHQ-9); if patients met the criteria for 2 weeks they were eligible for inclusion
- Patients with psychosis, type I or II bipolar disorder, suicidal thoughts, and those accessing services for substance misuse or depression were excluded.
Participants attending GP practices allocated to the collaborative care arm received up to 8 face-to-face sessions of brief psychological therapy delivered by a case manager over 3 months. Up to two 10-minute collaborative meetings between the participant, psychological well-being practitioners and a practice nurse from the participant’s GP were offered following treatment session two and session eight, to facilitate the integration of care.
The primary outcome was the self-reported symptom checklist-depression scale (SCL-D13).
For the health economic analysis healthcare utilisation data were collected with a patient questionnaire and health status was measured with the EuroQol 5D-5L (EQ-5D-5L). The economic evaluation was from the perspective of the English NHS. National costs were applied to healthcare utilisation data (2015-2016 British pounds). The primary measure of cost-effectiveness was cost per quality adjusted life-year (QALY). The mean cost of the collaborative care intervention was £321, including a training cost of £130 per participant.
In total, 191 participants were allocated to collaborative care and 196 to usual care. The results are summarised as follows:
- At 24 months, the mean SCL-D13 score was -0.27 (95% CI, -0.48 to -0.06) in the collaborative care group
- At 24 months, collaborative care was associated with a gain of 0.14 (95% CI, 0.06 to 0.21) QALYs but a higher net cost (£1,777, 95% CI, -£320 to £3875)
- The cost per QALY gained was £13,069
- The probability of collaborative care being cost-effective is 0.75 if decision makers are willing to pay £20,000 to gain one QALY, and 0.92 if they are willing to pay £30,000 per QALY.
- The cost per QALY gained was £13,069
The researchers concluded:
In the long term, collaborative care reduces depression and is potentially cost-effective at internationally accepted willingness to-pay thresholds.
Strengths and limitations
This study fills an important gap in the literature, providing long-term evidence on collaborative care in a UK setting, addressing an evidence gap identified by NICE (NICE, 2016). Overall, the methods employed in the study were robust and the economic evaluation adhered to reporting standards.
There were some limitations of the study:
- Health service use was not captured at baseline (thus underlying differences between treatment groups could not be adjusted for)
- The study was impacted by missing data, and the authors applied multiple imputation techniques to reduce the bias associated with this
- It should be noted that the attrition rate was higher among participants in the collaborative care group (37.7%) compared to the usual care group (26.0%), however it is unclear if this was related to health outcomes, intervention acceptability, or underlying differences between groups that were not captured/measured in the study.
It is not a limitation of the study, but it would be interesting to explore the number of sessions attended and any link to the effectiveness of the intervention. Communication with the lead author highlighted that the mean number of therapy sessions was 4, with 52% of the intervention group having at least one collaborative meeting. This highlights that if effective, and effectiveness is linked to the number of sessions, there could be the potential for greater health gains.
With reports that the prevalence of multimorbidity is rising, especially in the case of aging populations, cost-effective interventions may be valuable in easing the burden on healthcare services (Cassell 2018). Combined with the existing literature on the favourable short-term effects of collaborative care, this study suggests that clinicians and other decision makers should consider collaborative care for the management of patients with mental and physical multimorbidity.
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