Remission in CBT for adult anxiety disorders: A meta-analysis

Highlights

• There is no universally accepted definition of remission in anxiety disorders.

• We conducted a meta-analysis of remission in cognitive-behavior therapy (CBT).

• The overall remission rate for the intent-to-treat samples was 48% at post-treatment and 54% at follow up while the remission rate for completer samples was 53% at post-treatment and 56% at follow up.

• Remission rates differed by definition, diagnosis, and various patient factors.

• Although CBT is effective for anxiety, there is significant room for improvement.

Abstract

Currently there is no universally accepted definition of remission in anxiety disorders. This may be causing significantly different estimates of treatment efficacy across anxiety disorders. The aim of this paper was to determine not only the overall remission rate in cognitive-behavioral therapy (CBT) for anxiety disorders, but also to examine whether the different definitions of remission lead to significantly different remission rates. From the initial 228 abstracts reviewed by the authors, 100 articles were retained. The overall mean remission rate was 51.0%. Remission rates were highest when remission was defined as good end state functioning or no longer meeting criteria for the primary diagnosis. Studies of posttraumatic stress disorder had the highest remission rates, while those of obsessive-compulsive disorder and social anxiety disorder had the lowest remission rates. Rates of remission differed by certain demographic (e.g., older age) and clinical (e.g., medication use) characteristics. Although CBT is an empirically supported treatment for anxiety disorders, it is clear that there is room for improvement, as many patients do not achieve remission status.

Introduction

The efficacy of cognitive behavioral therapy (CBT) for anxiety disorders is well established with multiple controlled trials demonstrating that CBT outperforms not only waitlist and placebo controls but also other psychological treatments (Butler, Chapman, Forman, & Beck, 2006; Tolin, 2010). Meta-analytic reviews of CBT for anxiety disorders have commonly found medium to large effect sizes from pre- to post-treatment, depending on the anxiety disorder (Butler et al., 2006; Olatunji, Cisler, & Deacon, 2010). A recent meta-analysis of response rates in CBT for anxiety suggest a less optimistic view of CBT efficacy; there was a 49.5% response rate at post-treatment and a 53.6% response rate at follow-up (Loerinc et al., 2015).

One complication with interpreting the Loerinc et al. (2015) meta-analysis is that the constructs of response and remission were combined. Therefore, we examined how different definitions of remission lead to different remission rates among the anxiety disorders. Response refers to overall change over the course of treatment (e.g., a patient exhibited a 25% or greater reduction in symptoms). However, a patient could exhibit clinical response but still be quite impaired. For example, a patient with obsessive-compulsive disorder (OCD) might show a decrease in Yale-Brown Obsessive-Compulsive Scale (Y-BOCS; Goodman et al., 1989) scores from 32 to 20; although that is more than a 25% decrease (and thus the patient may be considered a responder), the post-treatment score is still in the moderate range, suggesting clinically elevated symptoms. Remission, on the other hand, refers to end status after treatment; in other words, a patient in remission is considered “well.” This is a critical distinction: in order to determine how well CBT impacts the substantial public health burden of anxiety disorders (Kessler, Alonso, Chatterji, & He, 2014), it is important to know not only how many patients show a change in symptoms, but also how many can be considered “well” after treatment.

Remission has been defined in several different ways. One common definition is that the patient no longer meets diagnostic criteria for the disorder being treated. An important limitation of this definition is that a patient may no longer meet criteria for a diagnosis simply because he/she is one symptom short of the criteria, yet continue to have severe and impairing symptoms. Another definition of remission is scoring below a clinical cutoff on a continuous measure. However, some researchers have used cutoff scores that could still reflect the presence of mild to moderate symptoms (e.g., a Y-BOCS score of 15 or less). A third and related definition is clinically significant change (CSC; Jacobson & Truax, 1991), which can reflect post-treatment scores that are outside the pathological range, within the normative range, or past the midpoint between the pathological and normative ranges (McGlinchey, Atkins, & Jacobson, 2002). It is noted that some authors have confused CSC with reliable change (i.e., a degree of change that is unlikely to be due to measurement error); however, these constructs should be considered separately, as reliable change refers to movement over time (analogous to the construct of response) whereas CSC refers to end status (analogous to the construct of remission; Jacobson, Roberts, Berns, & McGlinchey, 1999). A fourth definition of remission is good (or high) end state functioning, a less well-defined construct that refers to overall psychological health across multiple domains of functioning, such as anxiety, depression, and general stress. Practically speaking, good end state functioning is often defined in treatment studies as scoring below cutoffs on measures not only of the disorder being treated, but also on measures of commonly co-occurring problems such as depression.

As can be seen from the wide range of remission definitions, as well as the fact that some authors have defined remission as a combination of two or more of these factors, it is clear that there is no universally accepted definition of remission in anxiety disorders, which may lead to significantly different estimates of treatment efficacy. It is important, therefore, to determine not only the overall remission rate in CBT for anxiety, but also to understand whether different definitions of remission lead to significantly different estimates. Of course, universally accepted and applied definitions are needed in order to clarify true remission rates in CBT.

To this end, the present meta-analysis examined rates of remission (defined as end state after treatment) in CBT for DSM-IV (American Psychiatric Association, 1994) anxiety disorders. Our primary aim was to compare remission rates across various definitions, including no longer meeting criteria for the primary diagnosis, CSC, scoring below a clinical cutoff, good end state functioning, and commonly used combinations of these definitions. A secondary aim was to compare remission rates across anxiety disorders. We also examined whether certain demographic variables (e.g., age, gender) and psychological factors (e.g., medication status, comorbidity) impacted remission rates.

In addition to establishing standardized definitions for remission, it is important to consider the methodological quality of the research. One might expect that key indices of methodological rigor (e.g., Foa & Meadows, 1997; Jadad et al., 1996), would affect remission estimates, with more rigorous trials yielding more conservative estimates. Accordingly, randomized controlled trials (RCTs) would be expected to yield lower remission rates than would open trials. Intent-to-treat (ITT) analyses would be expected to yield lower rates than would completer analyses. Studies that used independent evaluators, blind to treatment condition, would be expected to yield lower rates than would studies that used unblinded evaluators or self-report measures. Studies that used manualized treatments and assessed treatment fidelity would be expected to yield lower remission rates than would those that did not. Finally, studies that employed reliable and valid measures for the disorder being treated would be expected to yield lower remission rates than would those that used non-validated measures (e.g., daily diaries). In the present meta-analysis, we investigated whether these methodological quality factors impacted reported remission rates.