Relapse and Recurrence of Common Mental Health Problems after Low Intensity Cognitive Behavioural Therapy: The WYLOW Longitudinal Cohort Study

Publication Summary

The West Yorkshire Low Intensity Outcome Watch (WYLOW) was a prospective, longitudinal cohort study. The study recruited 439 patients with depression and anxiety disorders who completed LiCBT interventions in a stepped care psychological therapy service linked to the Improving Access to Psychological Therapies (IAPT) programme in England. LiCBT interventions were highly standardised, were delivered by trained psychological wellbeing practitioners, and included individual, group, and online forms of treatment delivery, consistent with clinical guidelines [9]. Participants were eligible for inclusion if they completed LiCBT with remission of depression and anxiety symptoms, which were established using diagnostic cut-offs on the PHQ-9 [10] and GAD-7 [11] measures. Participants were contacted once per month by the research team, and completed these measures to monitor their symptoms for up to 24 months. Cases that met the criteria for reliable (increase >5 points) and clinically significant (above diagnostic cut-off) deterioration of symptoms on any of the 2 measures during follow-up were classified as having a risk event. Consistent with previous research [1–3], a risk event was considered a relapse if it occurred within 12 months after treatment, and a recurrence if it occurred after 12 months. We performed a survival analysis using Kaplan-Meier (KM) curves to model “time to event” in months. KM curves plot the probability of survival (remission) over time, while taking account of censored (i.e., missing) data points. The sample included a majority of white British (94.2%) female participants (59.7%) with a mean age of 41.28 years (SD = 14.59), who on average accessed 7.04 (SD = 1.99) treatment sessions. Mean preand post-treatment measures were PHQ-9 = 13.60 (SD = 5.41) and 3.44 (SD = 2.40), respectively, and GAD-7 = 13.20 (SD = 4.38) and 3.19 (SD = 2.17). Full details about recruitment, inclusion criteria, and methods can be found in a preliminary report of 12-month outcomes [12]. The study was approved by the NHS Health Research Authority (Yorkshire and Humber REC; Ref. 12/YH/0095). Overall, 65.8% (95% CI: 59.3–72.2) of cases met criteria for a risk event within the 2-year follow-up period (34.2% remained in remission at 24 months). Figure 1 displays KM survival estimates, plotting the proportion of cases remaining in remission at each monthly measurement point. The figure quantifies cumulative relapse/recurrence rates at 6 (41.7%), 12 (52.8%), and 18 months (59.4%). The steeper inclination of the curve on the left side of the figure indicates that most risk events (77.8%) occurred within the first 6 months after treatment. Thereafter, 90.6% of events were observed by 12 months and 96.2% at 18 months. These results indicate that 24-month relapse/recurrence rates (65.8%) after completing LiCBT are twice as high as those observed in controlled trials of high intensity CBT [3, 4]. The limited durability of LiCBT for some patients could be related to structural constraints such as the lower number of sessions, or the emphasis on didactic treatment methods. This suggests that halving the length and intensity of treatment may also halve the durability of effects. The first 6 months after treatment should be considered a Depression and anxiety disorders are highly prevalent and relapse-prone conditions [1, 2]. Cognitive behavioural therapy (CBT), a well-established psychological intervention, has been shown to reduce the longer-term risk of depression relapse. For example, average relapse rates following CBT (∼30%) compare favourably to relapse rates observed after discontinued pharmacotherapy, which tend to be upwards of 50% [3, 4]. In spite of the effectiveness and durability of CBT for common mental health problems, barriers to its dissemination include the cost of delivery and the scarce availability of specialists in many countries. In order to overcome such barriers, briefer and less costly “low intensity” forms of CBT (LiCBT) have been developed to guide people on how they could self-manage and overcome their symptoms [5]. LiCBT can be delivered by trained coaches or lay helpers, using a variety of methods including individual, group-based, telephonebased, or online support. Meta-analyses of controlled trials support the use of LiCBT for the treatment of acute depression and anxiety symptoms, although there is still inconclusive evidence about its longer-term effects [6, 7]. Given its short-term duration (typically <8 sessions), LiCBT does not usually allow for intensive relapse prevention work or booster sessions that may account for the durability of more intensive CBT interventions [8]. For this reason, prospective follow-up studies are necessary to establish whether the effects of LiCBT are as durable as those observed in more conventional CBT interventions. This study reports relapse and recurrence rates in a cohort of patients who completed LiCBT in routine care, and who were followed up on a monthly basis for up to 2 years after treatment. Received: August 9, 2016 Accepted after revision: November 15, 2017 Published online: February 21, 2018