Psychological therapies for the treatment of depression in chronic obstructive pulmonary disease

Background: Chronic obstructive pulmonary disease (COPD) has been recognised as a global health concern, and one of the leading causes of morbidity and mortality worldwide. Projections of the World Health Organization (WHO) indicate that prevalence rates of COPD continue to increase, and by 2030, it will become the world's third leading cause of death. Depression is a major comorbidity amongst patients with COPD, with an estimate prevalence of up to 80% in severe stages of COPD. Prevalence studies show that patients who have COPD are four times as likely to develop depression compared to those without COPD. Regrettably, they rarely receive appropriate treatment for COPD-related depression. Available findings from trials indicate that untreated depression is associated with worse compliance withmedical treatment, poor quality of life, increased mortality rates, increased hospital admissions and readmissions, prolonged length of hospital stay, and subsequently, increased costs to the healthcare system. Given the burden and high prevalence of untreated depression, it is important to evaluate and update existing experimental evidence using rigorous methodology, and to identify effective psychological therapies for patients with COPD-related depression. Objectives: To assess the effectiveness of psychological therapies for the treatment of depression in patients with chronic obstructive pulmonary disease. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2018, Issue 11), and Ovid MEDLINE, Embase and PsycINFO from June 2016 to 26 November 2018. Previously these databases were searched via the Cochrane Airways and Common Mental Disorders Groups' Specialised Trials Registers (all years to June 2016). We searched ClinicalTrials.gov, the ISRCTN registry, and the World Healt hOrganization International Clinical Trials registry Platform(ICTRP) to 26 November 2018 to identify unpublished or ongoing trials. Additionally, the grey literature databases and the reference lists of studies initially identified for full-text screening were also searched. Selection criteria: Eligible for inclusion were randomised controlled trials that compared the use of psychological therapies with either no intervention, education, or combined with a co-intervention and compared with the same co-intervention in a population of patients with COPD whose depressive symptoms were measured before or at baseline assessment. Data collection and analysis: Two review authors independently assessed the titles and abstracts identified by the search to determine which studies satisfied the inclusion criteria.We assessed two primary outcomes: depressive symptoms and adverse events; and the following secondary outcomes: quality of life, dyspnoea, forced expiratory volume in one second (FEV1), exercise tolerance, hospital length of stay or readmission rate, and cost-effectiveness. Potentially eligible full-text articles were also independently assessed by two review authors. A PRISMA flow diagram was prepared to demonstrate the decision process in detail.We used the Cochrane 'Risk of bias' evaluation tool to examine the risk of bias, and assessed the quality of evidence using the GRADE framework. All outcomes were continuous, therefore, we calculated the pooled standardised mean difference (SMD) or mean difference (MD) with a corresponding 95% confidence interval (CI). We used a random-effects model to calculate treatment effects. Main results: The findings are based on 13 randomised controlled trials (RCTs), with a total of 1500 participants. In some of the included studies, the investigators did not recruit participants with clinically confirmed depression but applied screening criteria after randomisation. Hence, across the studies, baseline scores for depressive symptoms varied from no symptoms to severe depression. The severity of COPD across the studies was moderate to severe. Primary outcomes: There was a small effect showing the effectiveness of psychological therapies in improving depressive symptoms when compared to no intervention (SMD 0.19, 95% CI 0.05 to 0.33; P = 0.009; 6 studies, 764 participants), or to education (SMD 0.23, 95% CI 0.06 to 0.41; P = 0.010; 3 studies, 507 participants). Two studies compared psychological therapies plus a co-intervention versus the co-intervention alone (i.e. pulmonary rehabilitation (PR)). The results suggest that a psychological therapy combined with a PR programme can reduce depressive symptoms more than a PR programme alone (SMD 0.37, 95% CI -0.00 to 0.74; P = 0.05; 2 studies, 112 participants). We rated the quality of evidence as very low. Owing to the nature of psychological therapies, blinding of participants, personnel, and outcome assessment was a concern. None of the included studies measured adverse events. Secondary outcomes: Quality of life was measured in four studies in the comparison with no intervention, and in three studies in the comparison with education. We found inconclusive results for improving quality of life. However, when we pooled data from two studies using the same measure, the result suggested that psychological therapy improved quality of life better than no intervention. One study measured hospital admission rates and cost-effectiveness and showed significant reductions in the intervention group compared to the education group. We rated the quality of evidence as very low for the secondary outcomes. Authors' conclusions: The findings from this review indicate that psychological therapies (using a CBT-based approach) may be effective for treating COPDrelated depression, but the evidence is limited. Depressive symptoms improved more in the intervention groups compared to: 1) no intervention (attention placebo or standard care), 2) educational interventions, and 3) a co-intervention (pulmonary rehabilitation). However, the effect sizes were small and quality of the evidence very low due to clinical heterogeneity and risk of bias. This means that more experimental studies with larger numbers of participants are needed, to confirm the potential beneficial effects of therapies with a CBT approach for COPD-related depression. New trials should also address the gap in knowledge related to limited data on adverse effects, and the secondary outcomes of quality of life, dyspnoea, forced expiratory volume in one second (FEV1), exercise tolerance, hospital length of stay and frequency of readmissions, and cost-effectiveness. Also, new research studies need to adhere to robust methodology to produce higher quality evidence