How durable is the effect of low intensity CBT for depression and anxiety? Remission and relapse in a longitudinal cohort study

Highlights

• This longitudinal cohort study involved 439 patients who completed low intensity CBT.

• Patients provided depression and anxiety measures on a monthly basis up to 12 months post-treatment.

• Approximately 53% of cases relapsed within 1 year.

• Patients with residual depression symptoms at the end of treatment were twice as likely to relapse.

Abstract

Background

Depression and anxiety disorders are relapse-prone conditions, even after successful treatment with pharmacotherapy or psychotherapy. Cognitive behavioural therapy (CBT) is known to prevent relapse, but there is little evidence of the durability of remission after low intensity forms of CBT (LiCBT).

Method

This study aimed to examine relapse rates 12 months after completing routinely-delivered LiCBT. A cohort of 439 LiCBT completers with remission of symptoms provided monthly depression (PHQ-9) and anxiety (GAD-7) measures during 12 months after treatment. Survival analysis was conducted to model time-to-relapse while controlling for patient characteristics.

Results

Overall, 53% of cases relapsed within 1 year. Of these relapse events, the majority (79%) occurred within the first 6 months post-treatment. Cases reporting residual depression symptoms (PHQ-9 = 5 to 9) at the end of treatment had significantly higher risk of relapse (hazard ratio = 1.90, p < 0.001).

Conclusions

The high rate of relapse after LiCBT highlights the need for relapse prevention, particularly for those with residual depression symptoms.

Introduction

Depression is known to have a high recurrence rate, even after the successful treatment of acute-phase symptoms (Burcusa and Iacono, 2007, Gopinath et al., 2007, Hardeveld et al., 2010, Harter et al., 2007, Yiend et al., 2009). For example, after a first episode of depression, the probability of a further episode is approximately 50%; this rises to 70% following two episodes and 90% after a third episode (Burcusa and Iacono, 2007, Kessler et al., 1996). It also appears that with each further episode there is an increase in the severity of depressive symptoms and an increased probability that these symptoms will become resistant to treatment (Kendler, Thornton, & Gardner, 2000). Similarly, research on anxiety disorders suggests high recurrence rates between 39% and 56% after treatment (Bruce et al., 2005, Eisen et al., 1999, Vervliet et al., 2013).

Literature in the field draws conceptual distinctions between relapse –a deterioration after initial response to treatment– and recurrence –a new episode of the disorder following a period of recovery– (Bockting, Hollon, Jarrett, Kuyken, & Dobson, 2015). Meta-analyses of trials in this area show that accessing cognitive behavioural therapy (CBT) reduces the risk of depression relapse (Cuijpers et al., 2013, Vittengl et al., 2007) by comparison to acute-phase pharmacological treatment. The prophylactic effects of CBT appear to be as durable as to those of long-term maintenance on pharmacological treatment, but better at preventing relapse and recurrence compared to acute-phase pharmacological treatment without a maintenance phase (Hollon et al., 2005). Similarly, CBT is associated with sustained maintenance of improvements after the acute phase of treatment in various anxiety disorders (Otto, Smits, & Reese, 2005). It is, however, unclear if this apparent durability of therapeutic effects primarily applies to conventional CBT delivered by qualified psychotherapists or psychologists for up to 20 sessions, as applied in efficacy trials.

Recent decades have seen the development of briefer and ‘low intensity’ versions of CBT (LiCBT) which can be delivered as guided self-help interventions supported by didactic materials (Bennett-Levy, Richards, & Farrand, 2010). LiCBT is becoming a common form of psychological care in many services, for example it is the predominant treatment option offered to thousands of patients each year in the Improving Access to Psychological Therapies (IAPT) programme in England (Clark, 2011). LiCBT involves brief (<8 sessions), highly structured (manual driven) psycho-educational interventions delivered in a variety of flexible formats (e.g., in person, via telephone, in groups, assisted by computerized learning modules). In the UK, for example, LiCBT is typically delivered by coaches (psychological wellbeing practitioners) who do not have formal psychotherapy or clinical psychology qualifications, but who are trained to a standardized curriculum and competency framework (e.g., see Richards & Whyte, 2009).

Although LiCBT can be effective at alleviating symptoms of depression and anxiety (Gellatly et al., 2007), it is as yet unclear if these effects are sustained after the acute-phase of treatment. For example, Coull and Morris (2011) carried out a meta-analysis of 13 controlled trials comparing LiCBT versus waitlist or usual care controls, which estimated a statistically significant but small mean weighted effect size of d = 0.32 favouring LiCBT for 9 studies that reported follow-up data (up to 12 months), and this effect reduced to d = 0.19 after excluding a study with low quality rating. This finding is closely comparable to the statistically significant between-group effect size (d = 0.20) reported in a meta-analyses of computerized CBT for depression that examined (up to 4 months) follow-up assessments (Richards & Richardson, 2012). However, this stands in contrast to a meta-analysis of internet-based CBT for depressive and anxiety disorders which concluded that clinical improvements were maintained at follow-up (median of 26 weeks) with no evidence of relapse (Andrews, Cuijpers, Craske, McEvoy, & Titov, 2010). The mixed evidence about its therapeutic durability raises important questions about the clinical and cost-effectiveness of LiCBT interventions, particularly when delivered in routine care conditions. Furthermore, evidence from meta-analyses is usually expressed in the form of effect sizes, masking information about the actual numbers (and proportions) of cases that may have relapsed in primary studies.

This study presents the findings of a naturalistic cohort study investigating remission and relapse rates following the completion of LiCBT interventions delivered in routine clinical care. The objectives of this study were to quantify post-treatment relapse rates at 12 months’ follow-up and to explore predictors of time-to-relapse.