Sudden Gains in Internet-Based Cognitive Behavior Therapy for Body Dysmorphic Disorder

Journal Pre-proofs Sudden gains in Internet-based cognitive behavior therapy for body dysmorphic disorder Johan Bjureberg, Jesper Enander, Erik Andersson, Volen Z. Ivanov, Christian Rück, Lorena Fernández de la Cruz PII: DOI: Reference:

S0005-7894(19)30136-4 https://doi.org/10.1016/j.beth.2019.11.002 BETH 947

To appear in:

Behavior Therapy

Received Date: Accepted Date:

29 August 2019 8 November 2019

Please cite this article as: J. Bjureberg, J. Enander, E. Andersson, V.Z. Ivanov, C. Rück, L. Fernández de la Cruz, Sudden gains in Internet-based cognitive behavior therapy for body dysmorphic disorder, Behavior Therapy (2019), doi: https://doi.org/10.1016/j.beth.2019.11.002

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© 2019 Association for Behavioral and Cognitive Therapies. Published by Elsevier Ltd.

SUDDEN GAINS IN CBT FOR BDD

1 Word count Abstract: 250 words Main text: 4,609 words Tables and figures: 5

Sudden gains in Internet-based cognitive behavior therapy for body dysmorphic disorder Johan Bjureberg1,2, Jesper Enander1, Erik Andersson1, Volen Z. Ivanov1,2, Christian Rück1,2, Lorena Fernández de la Cruz1,2 1 Centre

for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet,

Stockholm, Sweden 2 Stockholm

Health Care Services, Stockholm County Council, Stockholm, Sweden

Author Note: This study was funded through the regional agreement on medical training and clinical research (ALF) between the Stockholm County Council and Karolinska Institutet, the Swedish Research Council (grant No: K2013-61X-22168-01-3), and the Swedish Society of Medicine (Söderströmska Königska sjukhemmet, grant No: SLS3B4451). Funders had no part in the study design, in the collection, analysis and interpretation of data, in the writing of the report or in the decision to submit the article for publication. Address correspondence to Lorena Fernández de la Cruz, PhD, Department of Clinical Neuroscience, Karolinska Institutet, Child and Adolescent Psychiatry Research Center, Gävlegatan

22B,

floor

[email protected]

8,

11330

Stockholm,

Sweden;

e-mail:

SUDDEN GAINS IN CBT FOR BDD

2 Abstract

Sudden gains have been associated with better short- and long-term treatment outcomes in a number of psychiatric disorders. However, no studies to date have evaluated sudden gains in body dysmorphic disorder (BDD). We used data from a previous randomized controlled trial evaluating the efficacy of an Internet-based cognitive-behavior treatment (CBT) for BDD. The sample consisted of 47 adults diagnosed with BDD. We compared the treatment outcomes of sudden gainers vs. gradual gainers (i.e., treatment responders with no sudden gains) and non-sudden gainers (i.e., gradual gainers plus non-responders) at post-treatment and 3, 12, and 24 months after the end of the treatment. Twelve (25.5%) participants experienced a sudden gain. Compared to non-sudden gainers and to gradual gainers, sudden gainers showed significantly larger improvements on the Yale-Brown Obsessive-Compulsive Scale modified for BDD at post-treatment (g=1.23 and g=.91, respectively), and at 3-month (g=1.23 and g=1.00, respectively), 12-month (g=1.12 and g=.91, respectively), and 24-month follow-up (g=1.11 and g=.97, respectively). This translated into higher rates of treatment responders and remitters in the sudden gainers across all time points. The occurrence of sudden gains in Internet-based CBT for BDD is associated with favorable short- and longterm treatment outcomes. This suggests that a sudden improvement during the treatment could be a marker of good prognosis, while non-sudden – including gradual – gainers are more likely to need continued support or booster sessions. Early identification of patients who are not progressing as expected and subsequent tailoring of the delivered intervention has the potential to improve treatment outcomes in this group.

Keywords: body dysmorphic disorder; cognitive-behavior therapy; sudden gains; treatment response; clinical trials.

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SUDDEN GAINS IN INTERNET-BASED COGNITIVE BEHAVIOR THERAPY FOR BODY DYSMORPHIC DISORDER Body dysmorphic disorder (BDD) is a psychiatric condition defined by an excessive preoccupation with perceived defects in physical appearance that are either not observable or appear only slight to others. The preoccupation leads to avoidance, particularly of social situations, and time-consuming repetitive behaviors such as mirror checking, excessive grooming or reassurance seeking that cause distress and impairment (American Psychiatric Association, 2013). BDD affects about 2% of the population (Enander et al., 2018; Veale, Gledhill, Christodoulou, & Hodsoll, 2016), usually starts in adolescence (Bjornsson et al., 2013), and it is often a chronic disorder if left untreated (Phillips, Menard, Quinn, Didie, & Stout, 2013). Recommended evidence-based treatments for BDD include cognitive-behavior therapy (CBT) (Harrison, Fernández de la Cruz, Enander, Radua, & Mataix-Cols, 2016), clomipramine (Hollander et al., 1999), and selective serotonin reuptake inhibitors (SSRIs) (Phillips, Albertini, & Rasmussen, 2002; Phillips et al., 2016). Nonetheless, rates of treatment responders in participants enrolled in randomized controlled trials (RCTs) are suboptimal. Specifically, only about 40 to 56% of patients undertaking CBT are defined as responders at the end of the treatment (Enander et al., 2016; Mataix-Cols et al., 2015; Veale, Anson et al., 2014; Veale et al., 1996; Wilhelm et al., 2014) as per the most widely used definition of ≥30% reduction from baseline on the Yale-Brown Obsessive-Compulsive Scale modified for BDD (BDD-YBOCS) (Fernández de la Cruz et al., 2019; Phillips, Hart, & Menard, 2014). These rates of response are substantially lower than those found in RCTs of CBT for obsessive-compulsive disorder (OCD) – a condition phenomenologically similar to BDD – which range between 60 to 80% (Ost, Havnen, Hansen, & Kvale, 2015). Therefore, it seems critical from the clinical point of view to explore the mechanisms and processes involved in

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the response to BDD treatment since they may offer insights on how the treatment outcomes in this patient group may be improved. One of such processes is the course of symptoms during treatment. Tang and DeRubeis (1999) were the first ones to describe a group of patients who endured substantial and stable improvements in depressive symptom severity from one therapy session to the next. This phenomenon is known as sudden gain and has been generally associated with better both short- and long-term treatment outcomes, compared not only to those patients that do not achieve the desired response, but also to those patients that experience a more gradual, rather than sudden, symptom improvement (Aderka, Nickerson, Boe, & Hofmann, 2012; Tang & DeRubeis, 1999). Given the above-mentioned modest rates of treatment response to CBT for BDD, information on the variables or processes that can influence treatment trajectories and that may play a role on the individual’s treatment outcomes is paramount. Investigation of sudden gains may then help predicting short- and long-term outcomes and informing optimization of treatment interventions. Sudden gains have been evaluated in a number of psychiatric disorders, including depression (e.g., Tang & DeRubeis, 1999), obsessive-compulsive disorder (e.g., Abu Hamdeh et al., 2019; Storch et al., 2019), posttraumatic stress disorder (e.g., Aderka, Appelbaum-Namdar, Shafran, & Gilboa-Schechtman, 2011; Konig, Karl, Rosner, & Butollo, 2014), panic disorder (e.g., Clerkin, Teachman, & Smith-Janik, 2008; Nogueira-Arjona et al., 2017), social anxiety disorder (e.g., Hofmann, Schulz, Meuret, Moscovitch, & Suvak, 2006; Thorisdottir, Tryggvadottir, Saevarsson, & Bjornsson, 2018), generalized anxiety disorder (e.g., Present et al., 2008), health anxiety (e.g., Hedman et al., 2014), and anorexia nervosa (e.g., Brockmeyer et al., 2019; Cartwright, Cheng, Schmidt, & Landau, 2017). However, to our knowledge, no studies have previously attempted to study whether sudden gains also appear in the treatment of individuals with BDD and whether these are associated with a

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better prognosis. We cannot assume that previous findings in other disorders will also translate to BDD, particularly considering the above-mentioned differences in treatment response between BDD and similar phenotypes such as OCD. Hence, the aim of our study was to evaluate the short and long-term effects of sudden gains in CBT of BDD. To that end, we performed a secondary analysis of data from a previous RCT comparing Internet-based CBT and Internet-delivered supportive therapy where participants with BDD were treated and followed up to two years after the end of the treatment (Enander et al., 2016; Enander et al., 2019). We hypothesized that a proportion of individuals with BDD would experiment a sudden gain, most likely in the range of the proportions found in other studies of sudden gains in OCD, and that individuals that experienced a sudden gain during the course of their treatment would have larger short- and long-term improvements than those who were considered non-sudden gainers or gradual gainers. Material and methods Participants Data was obtained from an RCT where 94 individuals diagnosed with BDD where randomized to receive either Internet-based CBT treatment with therapist support (BDDNET) (n=47) or Internet-delivered supportive therapy (n=47) for a period of 12 weeks, with follow-ups 3, 12, and 24 months after the end of the treatment (Enander et al., 2016; Enander et al., 2019). For the purposes of this study, only the 47 individuals initially randomized to the BDD-NET arm were included. Full information about the trial design, inclusion and exclusion criteria, recruitment, treatment conditions, randomization, and blinding methods are detailed elsewhere (Enander et al., 2016; Enander et al., 2014). In brief, this was a single blind, parallel group, superiority

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trial conducted at Karolinska Institutet, Sweden. All participants were adults meeting diagnostic criteria for BDD, according to DSM-5 criteria, with a score of at least 20 on the BDD-YBOCS. All participants gave written consent for participating in the study, which was approved by the regional ethical review board in Stockholm (2013/1773-31/4). The trial was prospectively registered at ClinicalTrials.gov (NCT02010619). Assessment time-points and treatment outcome measures All participants were assessed at baseline and then received 12 weeks of treatment. Followup assessments were performed at post-treatment and 3, 12, and 24 months after the end of the treatment. The primary outcome measure was the BDD-YBOCS, which is the gold standard measure for the assessment of BDD symptom severity (Phillips et al., 2014). The measure is a semi-structured, clinician-administered scale including 12 items which assesses BDD symptom severity during the past week. Scores for each item range from 0 to 4; the total score ranges from 0 to 48, with higher scores reflecting more severe symptoms. The BDDYBOCS has shown good psychometric properties, including strong interrater and test-retest reliability, internal consistency, validity, and sensitivity to change (Phillips et al., 2014; Phillips et al., 1997). Reliability between raters in this study was excellent (intraclass correlation=.89-.98) (Enander et al., 2016). The internal consistency of the BDD-YBOCS in the present sample was good (α=.72). The measure was applied by experienced clinicians blind to treatment condition at all time-points. These assessors were blind to treatment allocation at post-treatment and at 3-month follow-up, but not at the 12- and 24-month follow-ups since blindness was broken at this stage as per protocol (Enander et al., 2019). Secondary outcome measures comprised a number of online self-report measures, including the Appearance Anxiety Inventory (AAI) (Veale, Eshkevari et al., 2014), which

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was completed weekly during the 12-week duration of the treatment. The AAI is a 10-item self-report questionnaire focusing on the cognitive processes and safe-seeking behaviors that are characteristic of a response to a distorted body image and associated shame (Veale et al., 2014). Scores for each item range from 0 to 4 to obtain a total score ranging from 0 to 40. Higher scores reflect greater severity. The AAI has demonstrated good internal consistency, test-retest reliability (intraclass correlation=.87), and validity (with correlations with the BDD-YBOCS in the large range), as well as sensitivity to change during treatment (Veale, Eshkevari et al., 2014). The internal consistency of the AAI in the present sample was good (α=.78). Internet-based cognitive behavior therapy (BDD-NET) The treatment consisted of a course of therapist-guided, Internet-based CBT for BDD, named BDD-NET, delivered through a secure online platform. Treatment lasted 12 weeks and the participants did not have any face-to-face contact with a therapist during the duration of the treatment. The treatment protocol is based on a CBT model for BDD which emphasizes the role of negatively reinforced avoidance and safety-seeking behaviors (e.g., mirror checking, camouflaging of the perceived defects) as maintaining factors of BDD. BDD-NET consists of eight interactive modules generally delivered over 12 weeks, with the first five modules containing the core treatment components. Each module is devoted to a special theme and covers psychoeducation (module 1), a CBT conceptualization of BDD (module 2), cognitive restructuring (module 3), exposure and response prevention (modules 4 and 5), values based behavior change (module 6), difficulties encountered during treatment (module 7), and relapse prevention (module 8). The participants had contact with an identified therapist throughout the entire treatment using a built-in email system on the BDD-NET webpage. Further information about the BDD-NET treatment and its delivery can be found in the original publication (Enander et al., 2016).

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Definitions of sudden gain, gradual gain, reversal of a sudden gain, treatment response, and remission Following the criteria by Tang and DeRubeis (1999), a sudden gain was defined as: 1. A large absolute gain between two consecutive assessments. In order to assess this criterion, we performed a calculation based on the reliable change index (RCI) as defined by Jacobson and Truax (1991). The RCI is calculated by subtracting pre-gain scores from post-gain scores and dividing the difference with the standard error of the difference (Sdiff). In this framework, RCI values above 1.96 (p<.05) would be regarded as a significant change. Sdiff is derived from the standard error of measurements (SE). We estimated SEs by using the standard deviation of pretreatment AAI scores and the AAI test-retest reliability (ρI=.87) reported in Veale, Eshkevari et al. (2014). This led to a cut-off score of 6 on the AAI. 2. A large relative gain. This relative gain was set to be at least 25% of the pre-gain AAI score, as per the recommendation by Tang and DeRubeis (1999). 3. A stable gain. We used the modified criterion introduced by Tang, DeRubeis, Beberman, and Pham (2005). Thus, the difference in symptom scores between the three AAI scores before the gain and the three scores after the gain had to be at least 2.78 times greater than the pooled standard deviations of these two groups. When assessing the occurrence of a sudden gain at the third or second to last weekly assessment, where fewer data points (i.e., <3) were available, this cut-off was adapted based on adjusted degrees of freedom. A gain occurring at week one that fulfilled criteria 1 and 2 was considered a sudden gain if 50% of the improvement was maintained for at least two subsequent weeks (Gaynor et al., 2003). However, a large improvement registered at the last weekly assessment was not considered a sudden

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gain (even if criteria 1 and 2 were fulfilled), as it was not possible to assess the stability criterion. To study the relevance of the suddenness of the gain we controlled for the gain magnitude during treatment by comparing sudden gainers to gradual gainers. Following the criteria suggested by Greenfield, Gunthert, and Haaga (2011), individuals were classified as gradual gainers if they (a) did not meet the criteria to be sudden gainers but (b) experienced a gain of the same absolute (≥6 points on AAI) and relative magnitude (≥25%) as the sudden gainers but the gain occurred over several sessions. Thus, we compared the score of session 1 with the scores at sessions 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12, considering session 1 as the pregain session, while sessions 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 were possible after-gain sessions. Next, we compared the score of session 2 with sessions 4, 5, 6, 7, 8, 9, 10, 11, and 12, and so on. Reversal of a sudden gain was defined as a loss ≥50% of the symptom reduction on the AAI observed during the sudden gain at any point in the treatment following the gain (Tang & DeRubeis, 1999). Treatment response was defined as a ≥30% reduction on the BDD-YBOCS. This cutoff is the most widely used in the field and has shown empirical support (Fernández de la Cruz et al., 2019; Phillips et al., 2014). Remission was defined as patients who no longer met diagnostic criteria for BDD. Missing data Out of the total 564 AAI weekly measurements, 137 (24.3%) were missing. A total of 29 of the 47 included individuals (61.70%) had at least one missing weekly assessment. The highest frequency of missing data was seen at weeks 10 (19 missing points) and 11 (21 missing points), while the lowest frequency of missing values was seen at the beginning of

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the treatment (1 missing point at week 1, 4 at week 2) and in the last week (1 missing point at week 12), presumably reflecting efforts to collect full data at post-treatment. Little’s MissingCompletely-At-Random (MCAR) test (Little & Rubin, 1987) was non-significant (χ2=217.98, df=232, p=.737), indicating that missing data in our sample were missing completely at random (Little & Rubin, 1987). We chose not to impute missing data in order to avoid false positives. Statistical analysis We performed a series of linear mixed effects analyses with the AAI or the BDD-YBOCS as the dependent variables. Sudden gainers were compared to non-sudden gainers and gradual gainers in two separate models for both outcomes. Three fixed effects terms were entered in the models: sudden gain status (sudden gainers vs. non-sudden gainers and sudden gainers vs. gradual gainers), time (baseline to 12-week follow-up treated as continuous or pre-treatment, post-treatment, 3-, 12, and 24-month follow-up treated as discrete), and an interaction term between sudden gain status and time. Baseline (before treatment) scores on the BDD-YBOCS was included as a covariate in the models for the BDD-YBOCS. Participant varying intercepts were included as a random effect in all models and differences in trajectory of change were included as an additional random effect in the models for the AAI. We compared differences in baseline characteristics and scores on the AAI and the BDD-YBOCS in sudden gainers vs. non-sudden gainers and sudden gainers vs. gradual gainers using χ2 tests of independence and two-sided independent t-tests. Effect sizes were calculated based on pooled standard deviations using Hedges’s g. Between-group frequencies of treatment responders, remitters and recovered were tested using χ2 tests of independence. Results Gainer status and baseline characteristics

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A total of 12 participants (25.5%) were identified as sudden gainers and thus 35 participants (74.5%) were categorized as non-sudden gainers. Nine sudden gainers (19.1%) experienced one sudden gain and three (6.4%) experienced two sudden gains. Week 4 was the median week for the initial sudden gain. All sudden gains occurred before or at week 7, and 75% of the initial sudden gains occurred before or at week 5. Twenty-one of the 35 non-sudden gainers experienced a gain over the course of several sessions (but not between two consecutive sessions) and were thus identified as gradual gainers (44.7% of total sample). Demographic and clinical baseline characteristics by gainer status (i.e., sudden gainers, non-sudden gainers, gradual gainers) are presented in Table 1. Sudden gainers did not differ significantly from non-sudden gainers or gradual gainers on any baseline characteristics, with one exception. Sudden gainers were significantly less likely to have received previous psychosocial treatment for anxiety or depression, compared to gradual gainers (χ21,33=3.93, p=.047). Reversal of gains Of the 12 participants who experienced sudden gains, four (33.3%) had a reversal of the gain during treatment. Three of the participants with a reversal had a lower AAI score posttreatment compared with the post-gain score. Thus, for these three participants, the reversal was temporary and the sudden gain was fully maintained post-treatment. The fourth participant who experienced a reversal of the gain had similar post-treatment and pre-gain AAI scores, suggesting that the gain was fully reversed by the end of treatment. Effects of sudden gains Pre-treatment BDD symptoms (as measured by the AAI and the BDD-YBOCS) did not differ between participants who experienced sudden gains and those who did not (mean [sd] AAI scores of 23.58 [6.44], 25.35 [5.54], and 25.09 [5.14] – all p’s for between-pairs t-tests >.10 –

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and mean [sd] BDD-YBOCS scores of 28.50 [4.96], 29.34 [5.10], and 29.38 [5.06] – all p’s >.10 – for sudden gainers, non-sudden gainers, and gradual gainers, respectively). The average sudden gain was 11.40 points (sd=5.37) on the AAI. Figure 1 shows weekly mean ratings on the AAI during treatment for sudden gainers, non-sudden gainers, and gradual gainers. We observed a statistically significant improvement favoring sudden gainers, compared with non-sudden gainers and gradual gainers, and on the AAI throughout treatment (β=.92, z=4.06, p<.001 and β=.59, z=2.57, p=.01, respectively). Table 2 presents the mean scores and effect sizes (compared to pre-treatment) in the clinician-administered BDD-YBOCS for the three groups. BDD-YBOCS scores were statistically significantly lower for sudden gainers than for non-sudden gainers at all timepoints, including post-treatment (β=8.20, z=3.24, p<.001), 3-months follow-up (β=9.97, z=3.90, p<.001), 12-months follow-up (β=8.97, z=3.37, p<.001), and 24-months follow-up (β=10.91, z=4.17, p<.001). All comparisons were accompanied with large effect sizes (Hedges’s gs ranging from 1.13 to 1.26) Similarly, when comparing sudden gainers with gradual gainers, statistically significant differences in BDD-YBOCS scores were detected at all time-points, including post-treatment (β=5.80, z=2.25, p=.024), 3-months follow-up (β=7.80, z=3.00, p=.003), 12-months follow-up (β=5.98, z=2.21, p=.027), and 24-months follow-up (β=9.16, z=3.42, p<.001), Hedges’s gs ranging from .93 to 1.03. Treatment response and remission As showed in Figure 2, a statistically significantly larger proportion of sudden gainers, compared to non-sudden gainers, were classified as responders at all time-points (posttreatment: 10/12 [83%] vs. 15/34 [44%], respectively; χ21, 46=5.50, p=.019; 3-months followup: 11/12 [92%] vs. 12/29 [41%], respectively; χ21, 41=8.72, p=.003; 12-months follow-up: 11/11 [100%] vs. 9/20 [45%], respectively; χ21, 31=9.38, p=.002; and 24-months follow-up: 12/12 [100%] vs. 13/21 [62%], respectively; χ21, 33=6.03, p=.014). When comparing sudden

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gainers vs. gradual gainers, the proportion of participants classified as responders (Figure 2) was also statistically significantly higher among sudden gainers at all time-points (posttreatment: 10/12 [83%] vs. 13/21 [62%], respectively; χ21, 46=5.50, p=.019; 3-months followup: 11/12 [92%] vs. 10/20 [50%], respectively; χ21, 32=5.77, p=.016; 12-months follow-up: 11/11 [100%] vs. 8/14 [57%], respectively; χ21, 25=6,20 p=.013, and 24-months follow-up: 12/12 [100%] vs. 9/14 [64%], respectively; χ21, 26=5.31, p=.021). Mirroring the results for responders, the proportion of participants classified as remitters (Figure 3) was statistically significantly higher among sudden gainers compared to non-sudden gainers at post-treatment (9/12 [75%] vs. 6/34 [18%], respectively; χ21, 30=13.28, p<.001), 3-month follow-up (9/12 [75%] vs. 7/28 [25%], respectively; χ21, 40=8.75, p=.003), 12-month follow-up (10/11 [91%] vs. 8/20 [40%], respectively; χ21, 31=7.55, p=.006), and 24month follow-up (12/12 [100%] vs. 9/21 [43%], respectively; χ21, 33=10.78, p=.001). A statistically significantly larger proportion of sudden gainers, compared to gradual gainers, was also classified as remitters at post-treatment (9/12 [75%] vs. 5/21 [24%], respectively; χ21, 33=8.19, p=.004), 3-months follow-up: 9/12 [75%] vs. 6/19 [32%], respectively; χ21, 31=5.55,

p=.018), 12-months follow-up (10/11 [91%] vs. 6/14 [43%], respectively; χ21,

25=6.17,

p=.013), and 24-months follow-up (12/12 [100%] vs. 7/14 [50%], respectively; χ21,

26=8.21,

p=.004). Discussion

This study aimed to explore, for the first time, the phenomenon of sudden gains in a sample of adults with BDD undergoing Internet-based CBT for the disorder. Our main goal was to test whether sudden gains were associated with better treatment outcomes, as it has been reported in other disorders. This knowledge could help us to better understand the mechanisms involved in response to treatment, which could inform treatment guidelines that may improve the outcomes in this patient group.

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About one fourth of the participants with BDD in our sample were classified as sudden gainers. This number is in the low end of the proportions found in the five published studies of sudden gains in CBT (both face-to-face and Internet-delivered) for OCD, a disorder in the same spectrum as BDD, where a wide range between 27 to 52% of participants were considered sudden gainers using similar definitions (Abu Hamdeh et al., 2019; Aderka, Anholt et al., 2012; Buchholz, Abramowitz, Blakey, Reuman, & Twohig, 2019; Collins & Coles, 2017; Storch et al., 2019). Our proportion, on the other hand, is more in line with those found in social anxiety disorder, a diagnosis that shares many similarities with BDD (Fang & Hofmann, 2010), such as the fear and avoidance of social situations, where rates of sudden gainers have been reported to be between 15 and 22% in group CBT (Hofmann et al., 2006; Thorisdottir et al., 2018), and higher than those proportions seen in health anxiety disorder (16%) also using an Internet-based treatment approach (Hedman et al., 2014). Similar to what it has been reported in previous studies (e.g., Abu Hamdeh et al., 2019; Storch et al., 2019), most participants (75%) experienced the sudden gain after the core therapeutic components – mainly exposure with response prevention – were introduced. This may suggest that, for a group of patients, the introduction of this specific technique during treatment leads to a potential cognitive change, which in turn leads to a further reduction in symptoms. This is what Tang and DeRubeis (1999) referred to as “upward spiral”. In this sense, from the clinical perspective, it would be important to introduce exposure early during the course of the treatment and provide more sessions of exposure with response prevention to those not achieving the expected gain in order to motivate an upward spiral. However, these upward spirals do not seem to be limited to the introduction of exposure and response prevention (or other specific CBT techniques) since, in other studies, sudden gains have shown to appear throughout treatment (Buchholz et al., 2019; Collins & Coles, 2017). Rather,

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as pointed out by Aderka, Nickerson et al. (2012) they may be the result of a number of different mechanisms, including but not limited to specific behavioral or cognitive techniques (e.g., exposure with response prevention), the role of the therapist, or skills acquisition. It is important that future studies identify what specific therapeutic factors are related with the onset of sudden gains in BDD. Importantly, individuals with BDD classified as sudden gainers did not differ from the gradual or the non-sudden gainers on BDD symptom severity or insight. Hence, the ability to make a sudden gain during treatment does not seem to be related with having more room for improvement or with the degree of awareness into their difficulties, the latter often linked with the reluctance to seek and receive help in BDD. Nonetheless, it is important to note that our sample was self-referred, which indicates at least some degree of motivation towards treatment. One third of the sudden gainers (n=4) experienced a reversal of the gain. This proportion is slightly higher than the range between 17 to 30% of reversals reported in previous RCTs (Aderka, Anholt et al., 2012; Hardy et al., 2005; Tang & DeRubeis, 1999). However, for three-fourths of the individuals with reversal gains, the reversal was only temporary since they managed to go back to post-gain scores before the end of the treatment. This indicates that, in general, sudden gains are a stable pattern of responding to treatment which may be responsible for better outcomes in the group experiencing them. Indeed, according to the weekly measure, sudden gainers had improved more than the other two groups at the end of the treatment, and this difference also translated into higher proportions of responders and remitters from post-treatment and up to two years after the end of the intervention. This suggests that a sudden improvement during the treatment could be a marker of good short- and long-term prognosis. This knowledge could help designing stepped-care treatment strategies in which gradual gainers (and obviously also those not

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achieving the desired response at the end of the treatment) would benefit from more continued support or booster sessions, while a less-intensive follow-up could be used for the sudden gainers, allowing for a more cost-effective distribution of clinical resources. Further experimental studies which randomly allocate patients to treatments of different intensities are warranted in order to confirm this interpretation. In this line, one recent trial on Internetdelivered CBT for patients with insomnia (Forsell et al., 2019) showed that it is possible to prevent treatment failures by identifying high-risk patients in the early stages of treatment and subsequently upscaling the intervention delivered to this group. Identification at baseline of the variables that predict the ability to make a sudden gain during treatment for BDD warrants further investigation since this knowledge would potentially allow to tailor the treatment by gain status, which may improve treatment outcomes. This study has a number of limitations. First, the study included a significant number of missing values on the weekly AAI assessments. Because it is not possible to assess the three criteria for sudden gain (i.e., size of gain, relativeness, and stability of gain) for any data point immediately before or after the missing value, missingness on the AAI may result in false negatives. However, because imputation methods to handle missing data may result in additional participants being identified as sudden gainers, we chose against imputing data to avoid false positives. Thus, missing data points could have resulted in a potentially meaningful impact on the classification of participants as sudden gainers, gradual gainers, or none of the mentioned. Future studies should be planned in every detail to reduce the risk of missing data. Second, the study did not measure, and therefore was unable to control for, other variables that could have contributed to the sudden gains (e.g., motivation, time spent in the online platform). Third, given that this study reports on an Internet-based treatment to which the patients have access according to their convenience and where they can follow their own pace, it is possible that there is a discrepancy between the treatment progress (i.e.,

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module of treatment that the participant is completing) and the time of assessment. However, our results are in line with previous literature in sudden gains reporting on face-to-face treatment studies of anxiety disorders where the occurrence of the sudden gains also coincides with the time where exposure has been introduced (e.g., Hofmann et al., 2006; Storch et al., 2019). In any case, further sudden gains studies in samples of BDD patients treated using face-to-face modalities are warranted in order to properly assess the impact of the mode of delivery on the results. Fourth, our analyses did not take into account other variables that may have contributed to the sudden gains. It might be that the group of sudden gainers included those individuals with higher motivation, connecting to the treatment platform more often than the non-sudden gainers or gradual gainers, or those that were more amenable to the intervention, as it may be suspected by the lower proportion of patients in this group who had previously received psychosocial treatment for anxiety or depression, which may have led to a faster progression in their treatment response. Lastly, this study included participants in an RCT who were self-referred and presented overall with mild to moderate BDD symptoms, for which results might not be generalizable to other samples of BDD cases. Future research should investigate if these findings also expand to more severe patients. Conclusions This is the first study to explore sudden gains in a BDD population. Our findings suggest that around one fourth of the patients experience a sudden gain coinciding with the introduction of the exposure and response prevention content in the treatment. Those individuals experimenting a sudden gain present with larger treatment effect sizes up to two years after the end of the treatment, compared to non-sudden gainers and gradual gainers. Monitoring and early identification of patients that are not performing as expected during treatment, and

SUDDEN GAINS IN CBT FOR BDD subsequent tailoring of the delivered intervention, may have the potential to improve treatment outcomes in patients with BDD.

18

SUDDEN GAINS IN CBT FOR BDD

19 References

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TABLES AND FIGURES Table 1. Sociodemographic and clinical characteristics of the sample (N=47), by gain status

Sudden

Non-Sudden

Gradual

Gainers

Gainers

Gainers

(n = 12)

(n = 35)

(n = 21)

Gender

Women

11 (92%)

28 (80%)

16 (76%)

Age

Mean age (sd)

32 (11)

35 (15)

34 (14)

Highest

Primary school

0 (0)

4 (11%)

2 (10%)

education

High school

10 (83%)

21 (60%)

12 (57%)

College/university

2 (17%)

9 (26%)

6 (29%)

Doctorate

0 (0%)

1 (3%)

1 (5%)

Occupational

Working

6 (50%

19 (54%)

12 (57%)

status

Student

4 (33%)

9 (26%)

6 (29%)

Retired

1 (8%)

1 (3%)

1 (5%)

Unemployed

1 (8%)

6 (17%)

2 (10%)

Years

16.5

15

15

Good

6 (50%)

13 (37%)

7 (33%)

Poor

4 (33%)

18 (51%)

13 (62%)

Delusional

2 (17%)

4 (11%)

1 (5%)

3 (25%)

10 (29%)

3 (25%)

Median duration of BDD Insight

Previous plastic surgery Previous

CBT for BDD

1 (8%)

4 (11%)

3 (14%)

treatments

Psychosocial treatment for

5 (42%)

25 (71%)

16 (76%)

anxiety or depression Current

SSRI

0 (0%)

5 (14%)

3 (14%)

medication

Other antidepressants

1 (8%)

4 (11%)

2 (10%)

Other psychotropics

1 (8%)

7 (20%)

3 (14%)

SUDDEN GAINS IN CBT FOR BDD Comorbidity

28

Current depressive episode

6 (50%)

22 (63%)

14 (67%)

Panic disorder

0 (0%)

2 (6%)

1 (5%)

Social anxiety disorder

4 (33%)

11 (31%)

6 (29%)

Generalized anxiety disorder

1 (8%)

8 (23%)

5 (24%)

Bulimia nervosa

0 (0%)

2 (6%)

1 (5%)

Obsessive-compulsive disorder

3 (25%)

5 (14%)

2 (10%)

Note: BDD, body dysmorphic disorder; CBT, cognitive-behavior therapy; SNRI, selective norepinephrine reuptake inhibitors; SSRI, selective serotonin reuptake inhibitors.

SUDDEN GAINS IN CBT FOR BDD

29

Table 2. Clinician-administered BDD-YBOCS scores and between-group effect sizes (Hedge’s g) at each time point, by gain status

Non-Sudden Sudden Gainers

Gradual Gainers

Between-Group Effect Size (95% CI)

Gainers Timepoint

n

M (SD)

n

M (SD)

n

M (SD)

Sudden Gainers

Sudden Gainers

vs. Non-Sudden

vs. Gradual

Gainers

Gainers

PRE

12

28.50 (4.96)

35

29.34 (5.10)

21

29.38 (5.06)

–

–

POST

12

13.58 (6.71)

34

22.32 (7.08)

21

19.71 (6.50)

1.23 (0.53-1.92)

0.91 (0.17-1.63)

3mFU

12

12.25 (7.39)

29

21.93 (7.83)

20

19.90 (7.47)

1.23 (0.51-1.94)

1.00 (0.25-1.74)

12mFU

11

8.82 (4.29)

20

18.40 (9.84)

14

15.50 (8.68)

1.12 (0.34-1.88)

0.91 (0.09-1.71)

24mFU

12

5.83 (4.93)

21

16.95 (11.66)

14

14.86 (11.36)

1.11 (0.35-1.84)

0.97 (0.17-1.76)

Note: PRE, pre-treatment; POST, post-treatment; 3mFU, 3-month follow-up; 12mFU, 12-month follow-up; 24mFU, 24-month follow-up; CI, confidence interval.

SUDDEN GAINS IN CBT FOR BDD Figure 1. Mean scores on the Appearance Anxiety Inventory (AAI) in sudden gainers, nonsudden gainers, and gradual gainers. Error bars indicate 95% confidence interval

30

SUDDEN GAINS IN CBT FOR BDD

31

Figure 2. Proportion of sudden gainers, non-sudden gainers, and gradual gainers classified as responders to treatment for body dysmorphic disorder

SUDDEN GAINS IN CBT FOR BDD

32

Figure 3. Proportion of sudden gainers, non-sudden gainers, and gradual gainers no longer meeting criteria for body dysmorphic disorder

Highlights 

One fourth of patients with BDD experienced a sudden gain during the treatment.



Sudden gainers had larger treatment effect sizes up to 2 years after the treatment.



Sudden gainers presented with higher rates of treatment response and remission.



Sudden improvements during BDD treatment could be a marker of good prognosis.



Identification of gain status could help designing tailored treatment strategies.