Psychotherapy for Major Depressive Disorder and Generalized Anxiety Disorder: A Health Technology Assessment

Major depressive disorder and generalized anxiety disorder are among the most commonly diagnosed mental illnesses in Canada; both are associated with a high societal and economic burden. Treatment for major depressive disorder and generalized anxiety disorder consists of pharmacological and psychological interventions. Three commonly used psychological interventions are cognitive behavioural therapy (CBT), interpersonal therapy, and supportive therapy. The objectives of this report were to assess the effectiveness and safety of these types of therapy for the treatment of adults with major depressive disorder and/or generalized anxiety disorder, to assess the cost-effectiveness of structured psychotherapy (CBT or interpersonal therapy), to calculate the budget impact of publicly funding structured psychotherapy, and to gain a greater understanding of the experiences of people with major depressive disorder and/or generalized anxiety disorder.

We performed a literature search on October 27, 2016, for systematic reviews that compared CBT, interpersonal therapy, or supportive therapy with usual care, waitlist control, or pharmacotherapy in adult outpatients with major depressive disorder and/or generalized anxiety disorder. We developed an individual-level state-transition probabilistic model for a cohort of adult outpatients aged 18 to 75 years with a primary diagnosis of major depressive disorder to determine the cost-effectiveness of individual or group CBT (as a representative form of structured psychotherapy) versus usual care. We also estimated the 5-year budget impact of publicly funding structured psychotherapy in Ontario. Finally, we interviewed people with major depressive disorder and/or generalized anxiety disorder to better understand the impact of their condition on their daily lives and their experience with different treatment options, including psychotherapy.

Interpersonal therapy compared with usual care reduced posttreatment major depressive disorder scores (standardized mean difference [SMD]: 0.24, 95% confidence interval [CI]: -0.47 to -0.02) and reduced relapse/recurrence in patients with major depressive disorder (relative risk [RR]: 0.41, 95% CI: 0.27-0.63). Supportive therapy compared with usual care improved major depressive disorder scores (SMD: 0.58, 95% CI: 0.45-0.72) and increased posttreatment recovery (odds ratio [OR]: 2.71, 95% CI: 1.19-6.16) in patients with major depressive disorder. CBT compared with usual care increased response (OR: 1.58, 95% CI: 1.11-2.26) and recovery (OR: 3.42, 95% CI: 1.98-5.93) in patients with major depressive disorder and decreased relapse/recurrence (RR: 0.68, 95% CI: 0.65-0.87]). For patients with generalized anxiety disorder, CBT improved symptoms posttreatment (SMD: 0.80, 95% CI: 0.67-0.93), improved clinical response posttreatment (RR: 0.64, 95% CI: 0.55-0.74), and improved quality-of-life scores (SMD: 0.44, 95% CI: 0.06-0.82). There was a significant difference in posttreatment recovery (OR: 1.98, 95% CI: 1.11-3.54) and mean major depressive disorder symptom scores (weighted mean difference: -3.07, 95% CI: -4.69 to -1.45) for patients who received individual versus group CBT. Details about the providers of psychotherapy were rarely reported in the systematic reviews we examined.In the base case probabilistic cost-utility analysis, compared with usual care, both group and individual CBT were associated with increased survival: 0.11 quality-adjusted life-years (QALYs) (95% credible interval [CrI]: 0.03-0.22) and 0.12 QALYs (95% CrI: 0.03-0.25), respectively.Group CBT provided by nonphysicians was associated with the smallest increase in discounted costs: $401 (95% CrI: $1,177 to 1,665). Group CBT provided by physicians, individual CBT provided by nonphysicians, and individual CBT provided by physicians were associated with the incremental costs of $1,805 (95% CrI: 65-3,516), $3,168 (95% CrI: 889-5,624), and $5,311 (95% CrI: 2,539-8,938), respectively. The corresponding incremental cost-effectiveness ratio (ICER) was lowest for group CBT provided by nonphysicians ($3,715/QALY gained) and highest for individual CBT provided by physicians ($43,443/QALY gained). In the analysis that ranked best strategies, individual CBT versus group CBT provided by nonphysicians yielded an ICER of $192,618 per QALY. The probability of group CBT provided by nonphysicians being cost-effective versus usual care was greater than 95% for all willingness-to-pay thresholds over $20,000 per QALY and was around 88% for individual CBT provided by physicians at a threshold of $100,000 per QALY.We estimated that adding structured psychotherapy to usual care over the next 5 years would result in a net budget impact of $68 million to $529 million, depending on a range of factors. We also estimated that to provide structured psychotherapy to all adults with major depressive disorder (alone or combined with generalized anxiety disorder) in Ontario by 2021, an estimated 500 therapists would be needed to provide group therapy, and 2,934 therapists would be needed to provide individual therapy.People with major depressive disorder and/or generalized anxiety disorder with whom we spoke reported finding psychotherapy effective, but they also reported experiencing a large number of barriers that prevented them from finding effective psychotherapy in a timely manner. Participants reported wanting more freedom to choose the type of psychotherapy they received.

Compared with usual care, treatment with CBT, interpersonal therapy, or supportive therapy significantly reduces depression symptoms posttreatment. CBT significantly reduces anxiety symptoms posttreatment in patients with generalized anxiety disorder.Compared with usual care, treatment with structured psychotherapy (CBT or interpersonal therapy) represents good value for money for adults with major depressive disorder and/or generalized anxiety disorder. The most affordable option is group structured psychotherapy provided by nonphysicians, with the selective use of individual structured psychotherapy provided by nonphysicians or physicians for those who would benefit most from it (i.e., patients who are not engaging well with or adhering to group therapy).