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. Author manuscript; available in PMC: 2023 Mar 1.
Published in final edited form as: Behav Ther. 2021 Aug 30;53(2):255–266. doi: 10.1016/j.beth.2021.08.003

Sudden gains in two trauma-focused treatments for posttraumatic stress disorder

Denise M Sloan 1,2,3, Johanna Thompson-Hollands 1,2,3, Adele Hayes 4, Daniel J Lee 1,2,3, Elizabeth Alpert 4, Brian P Marx 1,2,3
PMCID: PMC8896295  NIHMSID: NIHMS1736806  PMID: 35227402

Abstract

In the current study, we examined the degree to which sudden gains (large, rapid, and stable symptom reduction in a one-session interval) predicted treatment outcome in adults randomized to two different trauma-focused treatments. Adults diagnosed with PTSD were randomized to either written exposure therapy (WET; n = 63), a brief, exposure-based treatment for posttraumatic stress disorder (PTSD), or the more time-intensive Cognitive Processing Therapy (CPT; n= 63). Findings showed that 20.6% of participants who received WET and 17.5% of participants who received CPT experienced sudden gains. Sudden gains occurred earlier in WET (M session=2.69, SD = 0.75) than in CPT (M session=5.64, SD = 3.01). However, there were no treatment condition differences in the magnitude of the sudden gains. Treatment outcomes were significantly better for those who experienced sudden gains compared with those who did not, regardless of treatment assignment. Exploratory analyses of participants’ trauma narratives revealed that expressing more negative emotion predicted the occurrence of sudden gains in both treatment conditions. Negative beliefs about the self and others did not predict sudden gains. The findings are discussed in terms of how they may help identify individual early response patterns that predict outcomes in trauma-focused treatments.

Keywords: trauma, cognitive behavior therapy, exposure treatment, treatment mechanisms, written exposure therapy, cognitive processing therapy

The sudden gain pattern of symptom change has been identified as an important predictor of individual responses in cognitive behavioral therapy for depression and anxiety disorders (for a review see, Shalom & Aderka, 2020). A sudden gain is defined as a large, rapid (i.e., from one session to another), and stable reduction in symptoms (Tang & DeRubeis, 1999). Prior studies have found that sudden gains significantly predict better treatment outcomes and lower rates of relapse for a range of mood and anxiety disorders (Aderka et al., 2012; Shalom & Aderka), even for particularly difficult to treat populations such as treatment-resistant depression (Abel et al., 2016) and eating disorders (Utzinger et al., 2016).

Only a few studies have examined client variables that predict sudden gains during cognitive behavioral therapy for mood and anxiety disorders. Identifying predictors of sudden gains could reveal important treatment targets to facilitate further change and better long-term outcomes. Tang and colleagues (Tang & DeRubeis, 1999; Tang et al., 2005) found that cognitive shifts occur in the sessions immediately before sudden gains in cognitive therapy for depression. Three studies used the CHANGE (Hayes et al., 2007), an observational coding system of therapeutic change processes, to identify variables that differentiated those with and without sudden gains in cognitive-behavioral treatments for depression. These studies also found that cognitive variables (i.e., more hope and perspective shifts) differentiated those with and without early gains (Abel et al., 2016; Adler et al., 2013; Hayes et al., 2007).

Although a substantial number of studies have examined sudden gains in mood and anxiety disorders, less attention has been paid to investigating sudden gains in PTSD treatments. Examination of sudden gains could advance our understanding of how PTSD treatments have their effects and could identify early predictors of treatment response. This knowledge would be critical, given the lack of knowledge on who reaps the greatest benefit from evidence-based PTSD treatments (Cusack et al., 2016). Studies conducted to date indicate that sudden gains do occur during the course of PTSD treatment, although the percent of individuals experiencing a sudden gain has ranged considerably from 15% (Haugen et al., 2015) to 52% (Doane et al., 2010). When reported, sudden gains are most likely to occur in the middle of treatment (Aderka et al., 2011; Doane et al., 2010; Jun et al., 2013, Kelly et al., 2009; Konig et al., 2014). When comparison treatment conditions are included, no differences are observed in the percentage of individuals with sudden gains, the magnitude of sudden gains, the timing of the gains, or whether the gains predict post-treatment treatment outcome (Aderka et al., 2011; Jun et al., 2013; Kelly et al., 2009; Konig et al., 2014). Only a few studies have examined whether sudden gains were associated with PTSD symptom severity at follow-up. One study found that sudden gain status was not a significant predictor of better long-term PTSD outcomes (Konig et al., 2014), whereas two other studies found that gains did predict better long-term PTSD outcome (Aderka et al., 2011; Wiedemann et al., 2020).

Identifying predictors of sudden gains has clear clinical implications, yet very few studies have examined this in PTSD treatment. Neither PTSD symptom severity nor posttraumatic cognitions at baseline have been found to predict sudden gains in prolonged exposure or Sertraline treatments (Jun et al., 2013) or in cognitive therapy for PTSD delivered in routine clinical care (Weidemann et al., 2020). The only baseline variable thus far that has been identified as a predictor of sudden gains in prolonged exposure is younger age (Jun et al., 2013). It might be more fruitful to examine variables during, rather than before, treatment.

In a recent empirical review of potential mediators of exposure-based treatments for PTSD, Cooper et al. (2017) identified trauma-related belief change as having strong support in longitudinal, lagged analyses and emotional engagement as having mixed support, mostly due to inconsistent measurement. Maladaptive trauma-related beliefs are also a central target of cognitively-based treatments for PTSD, such as cognitive therapy (Ehlers et al., 2005) and cogntive processing therapy (CPT; Resick et al., 2016). The activation and engagement of negative emotion is also viewed as critical across PTSD treatments, when recounting trauma memories and facilitating cognitive and emotional processing of traumatic experiences (Asnaani et al., 2016; Resick et al. 2017; Sloan et al., 2007). Thus, trauma-related negative beliefs and negative emotions might also be related to sudden gains.

Cognitive factors such hope and perspective shifts early in treatment have been found to precede sudden gains in CBT for depression (Abel et al., 2016; Adler et al., 2013; Hayes et al., 2007), but the association between cognitive variables and sudden gains in treatments for PTSD is not yet clear. Weidemann et al. (2020) found that more change in negative trauma-related appraisals (Posttramatic Cognitions Inventory: PTCI-20) during cognitive therapy preceded sudden gains in PTSD symptoms. In addition, this cognitive change was larger for those with gains than than for matched clients without sudden gains. This is the only study that we are aware of that has examined cognitive variables and sudden gains in PTSD treatment. The role of trauma-related negative emotions in the sudden gain phenomenon has not been examined in PTSD treatments.

The current study study offers an opportunity to examine the role of cognitive change amd emotional expression in CPT, a cognitively-based psychotherapy for PTSD, and in written exposure therapy (WET; Sloan & Marx, 2019), an exposure-based PTSD treatment. We also use independent coders to rate client narratives about their traumatic experiences, rather than relying only on self-report measures. In the randomized controlled trial that is the data source for this study, WET was found to be non-inferior to CPT in PTSD at every assessment in the study across a period of approximately one year (Sloan et al., 2018). Based on the primary outcome findings (Sloan et al. 2018), we predicted that WET and CPT would not differ in the percentage of participants who experienced sudden gains or the magnitude of the sudden gains. In addition, based on previous sudden gain studies, we expected that experiencing a sudden gain would predict better PTSD treatment outcome in both trauma-focused treatments.

Clients in WET and CPT are required to write narratives about their traumatic experiences, and these narratives can be coded to provide another source of information beyond self-report that might reveal predictors of sudden gains. Given that self-reported cognitive change preceded sudden gains in one study of cognitive therapy for PTSD (Wiedemann et al., 2020), we used the CHANGE coding system (Hayes et al., 2007) to examine negative beliefs about the self and others in the first narratives of WET and CPT as predictors of sudden gains in this trial. In addition, because of the theoretical importance of affective engagement across different trauma-focused treatments (Asnaani et al., 2017; Sloan et al., 2007), we also investigated whether more expression of negative emotions in the narratives was associated with experiencing a sudden gain. Because no clear baseline predictors of sudden gains have been identified to date, we also examined a number of demographic and baseline variables (e.g., age, PTSD severity, depression severity, time since traumatic event) that have been investigated in prior sudden gain studies. Given that only one study (Wiedemann et al., 2020) identified a predictor (change in trauma-related cognitions) of who does and does not experience sudden gains in PTSD treatments, the analyses on predictors of sudden gains were considered exploratory.

Method

Participants

Participants were 126 treatment-seeking adults (52% male) diagnosed with PTSD who were randomized to either WET (n=63) or CPT (n=63). The mean age of the sample was 43.9 (SD = 14.6). The sample was racially diverse with 55% White, 34% African-American, and the remaining 11% other or mixed racial background. To be eligible for the study (see Sloan et al., 2018; ClinicalTrials.gov identifier NCT01800773), individuals were required to meet Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5; American Psychiatric Association, 2013) criteria for PTSD and to be stable on any psychiatric medication for at least four weeks. Potential participants were excluded if they were currently at high risk for suicide, were actively psychotic or manic, had severe cognitive impairment, currently met criteria for a severe substance abuse, or were currently engaged in PTSD-focused psychotherapy. The study assessment procedure is described in detail elsewhere (Sloan et al., 2018). The study was approved by institutional review boards at Boston University and VA Boston Healthcare System. All participants provided written informed consent.

Measures

Sudden gains were identified using ratings on the PTSD Checklist for DSM-5 (PCL-5; Weathers et al., 2013) administered at each treatment session. Respondents rated the degree to which they had been bothered by each of the 20 DSM-5 PTSD Criteria B-E symptoms during the past week (during treatment) or past month (at assessment sessions) on a 5-point scale ranging from Not at all (0) to Extremely (4). Items were summed for a total score reflecting overall PTSD symptom severity, with the possible range of 0–80. The PCL-5 has demonstrated strong psychometric properties, including internal consistency, test-retest reliability, and concordance with clinician-administered measures in veteran, community, and undergraduate samples (Blevins et al., 2015; Bovin et al., 2016). Internal consistency for the PCL-5 total score was strong in the current study (α = .89).

The Clinician Administered PTSD Scale for DSM-5 (CAPS-5; Weathers et al., 2013) was used to assess diagnostic status and PTSD symptom severity at baseline and 6-, 12-, 24-, 36-, and 60-weeks post first treatment session. Clinical interviews were administered by independent evaluators, who were masters’ level or higher and masked to treatment condition and treatment progress. The CAPS-5 is a structured diagnostic interview; clinicians rate each PTSD symptom on a five-point scale ranging from Absent (0) to Extreme (4), considering both symptom frequency and intensity. Items are summed to create a total score reflecting overall PTSD symptom severity; higher scores indicate greater severity with possible score range of 0–80. Inter-rater reliability on the CAPS-5 in this study was very good (κ = .85). In this study, we used the CAPS-5 to examine whether individuals who experienced sudden gains had better treatment outcome (e.g., PTSD symptom severity) than individuals who did not experience sudden gains.

We examined several variables as potential predictors of sudden gains. First, we assessed demographic variables of age and racial background using a demographic measure completed at baseline. We assessed depression severity at baseline with the Beck Depression Inventory, second edition (BDI-II; Beck et al., 1996). We measured estimated full-scale intelligence quotient (FSIQ) at baseline using the Wechsler Test of Adult Reading (WTAR; Wechsler, 2001). We examined FSIQ as a possible predictor of sudden gains because we found that this variable predicted treatment outcome for the CPT condition (Marx et al., 2021). As previously indicated, these analyses were exploratory given the lack of empirical investigation into sudden gains and limited theory regarding who is likely to experience sudden gains.

Using the CHANGE coding system (Hayes et al., 2007), we coded the first written narratives from participants in WET and CPT. The first narrative was coded to ensure that the written material occurred before the mean session of the sudden gain [WET (M session of sudden gain=2.69, SD = .075), CPT (M session=5.64, SD = 3.0)] and that there were enough narratives available for coding. Sixty-one (97% of 63) WET participants and 49 (78% of 63) CPT participants completed a first narrative. Most of the CPT narratives were missing because participants did not complete the assignment or indicated that they completed the assignment but did not bring the narrative to the session. The first narrative in WET is an account of the index trauma, with an emphasis on describing the thoughts and feelings at the time of the event (past). The first CPT narrative is an impact statement. Clients are asked to describe why the traumatic event happened and its effects on their current beliefs about themselves and others. For the impact statement, we coded the emotions described at the time of the event (past) and the impact on current beliefs about the self and others (present). Because the first narratives in WET and CPT included different writing instructions, we examined predictors of sudden gains in the WET and CPT conditions separately.

Each CHANGE variable is coded on a four-point scale from 0 (Absent or Very Low) to 3 (High). The coding system has been used to code narratives in a CBT treatment for depression (Hayes et al., 2005; Hayes et al., 2007) and in exposure-based treatments for adult PTSD (Alpert et al., 2020), as well as audio-recorded sessions of cognitive therapy for personality disorders (Hayes & Yasinski, 2015), juvenile PTSD (Ready et al., 2015), and treatment-resistant depression (Abel et al., 2016; Yasinski et al., 2019). Three of the coding categories included in the current study were: Negative view of self (negative beliefs about the self, including expressions of negative self-worth, self-criticism and blame, and feelings of failure), negative view of others (negative beliefs about relationships or interactions with others, including specific people and also people in general), and negative emotion (number and intensity of negative emotion words such as anxious, sad, angry, ashamed, guilty, also considering emotional tone). These variables were coded separately for present experiences (reported in the past week) and for past experiences (occurred during or around the time of the traumatic event).

A team of 10 graduate and undergraduate students coded the written narratives. Coders were trained in the CHANGE system and then coded with experienced coders until they reached a good level of agreement (intraclass correlations (ICCs) of ≥.80). The final estimates of agreement remained high for both present and past time frames (ICCs negative view of self: present=.91, past=.94; negative view of others: present=.90, past=.92; negative emotion: present=.92, past=.96). Two coders rated each narrative, and weekly meetings were held to prevent rater drift over time and to reach group consensus on discrepancies of two or more points on the 0–3 scale. If there was a discrepancy, consensus ratings replaced both coders’ ratings. The two coders’ ratings were then averaged to compute a final code. Coders were blind to study hypotheses, treatment condition, session number, and sudden gain status.

Treatment

Study Therapists.

Therapists held either a masters- or doctoral-level degree in psychology and had at least one year of experience in treating PTSD clients. Therapists were counterbalanced across the two treatment conditions and attended an initial training workshop for each treatment condition, followed by weekly supervision throughout the study. Adherence to the treatment protocol and competence in implementation were rated on separate scales, ranging from 1 (Poor) to 7 (Excellent). Ratings of 4 and above were considered satisfactory. As reported in Sloan et al. (2018), ratings were very good for both adherence (WET M = 5.81; CPT M = 5.71) and competence (WET M = 6.1; CPT M = 5.91)

Written Exposure Therapy.

WET consists of five weekly treatment sessions, with the first session lasting one hour and each subsequent session lasting approximately 45 minutes (Sloan & Marx, 2019). In the first session, the therapist educates the client about common reactions to trauma and provides the rationale for WET as a treatment for PTSD. The client is then given general instructions for completing the trauma narratives, specific instructions for completing the first session, and then is asked to complete the first 30-minute writing session. Clients are instructed to write about the same trauma during each session. This event is the same event identified as the index trauma during the baseline assessment session. The importance of delving into their deepest thoughts and emotions surrounding the traumatic event is emphasized, as well as the importance of providing detailed information about the event. All WET sessions begin with the therapist reading the specific writing instructions for that session and then leave the instructions with the individual, while the 30-minute writing session is completed alone. After 30 minutes, the therapist asks the client to stop writing and then checks in regarding their experience of the writing. This discussion is kept brief (i.e., less than 10 minutes) and does not include a recounting of the trauma narrative or cognitive processing of what was written.

Writing instructions begin with a focus on describing the details of the trauma and thoughts and emotions that occurred during the traumatic event and then shift over the five sessions to focus more on the meaning of the traumatic event (e.g., what the event has meant, how it has changed the way the person views his or her life). No between session homework assignments are included. After each session, the therapist reads the written narrative to make sure the client followed the writing instructions. At the start of subsequent writing sessions, the therapist provides feedback to the client regarding how well they followed the instructions.

Cognitive Processing Therapy.

CPT consists of 12, 60-minute sessions that primarily focus on challenging and changing distorted beliefs and self-blame regarding the traumatic event through Socratic questioning (Resick et al., 2016).1 In addition, several writing assignments are included in the treatment protocol. Specifically, after the first session, clients are asked to write an essay about why they think the index event occurred and how the traumatic event has impacted their beliefs about themselves and others. The impact statement is again assigned at session 11 and compared with the one written at the beginning of treatment to see how it changed. Between sessions 3 and 5, clients are instructed to write two detailed accounts of the index event as homework assignments, to read them every day, and to bring in these written accounts to be read out loud to the therapist during the next session. The rest of the therapy consists of sequential cognitive therapy practice assignments to teach clients to examine and modify their thoughts about their traumatic events and the consequences.

The written accounts in CPT differ from those in WET in several ways. First, they are written outside the therapy session as a homework assignment. Second, writing in WET occurs for 30 minutes, whereas the time frame is not specified for CPT. Third, the CPT protocol requires that clients read their narratives aloud to the therapist, whereas WET does not.

Although most of the efficacy and effectiveness trials for CPT have used the protocol that includes narrative written accounts, Resick and colleagues (2017) recommend using the version without trauma narrative accounts and now use the term CPT to refer to the modified version and use CPT plus written accounts to refer to the previous version of the treatment. The current study used the full CPT protocol; for clarity, we will use the term CPT to refer to the protocol version that includes the written accounts.

Procedure

A detailed description of study procedures is reported in Sloan et al. (2016). Briefly, participants were recruited from advertisements and direct referrals from community providers. Upon determining eligibility using diagnostic structured interviews, participants were randomized using a 1:1 allocation to either WET or CPT, resulting in a final sample of 126 individuals randomized. Dropout was defined as being randomized to one of the two treatments and not completing the full protocol (i.e., 5 sessions for WET and 12 sessions for CPT). As reported in Sloan et al. (2018), of the 63 people randomized to WET, four (6.3%) dropped out. Of the 63 randomized to CPT, 25 (36.6%) dropped out and one participant was withdrawn due to entry into a residential substance use disorder treatment program. There were no significant differences between participants who dropped out of treatment compared to treatment completers in terms of baseline PTSD symptom severity and demographic characteristics (e.g., age, race, sex).

Data Analysis of Sudden Gains

We followed Tang and DeRubeis’ (1999) requirements for identifying sudden gains. First, sudden gains should be large in absolute terms between any session N (pregain session) and session N + 1 (after-gain session). To identify sudden gains of PTSD symptoms, the reliable change index (RCI; Jacobson & Traux, 1991) was calculated for the PCL-5. Using the baseline (pre-treatment) standard deviation (14.10) and published test-retest reliability for the PCL-5 (.84; Bovin et al., 2016), the standard error of measurement was calculated as SE=14.101−.84=5.64. Standard error of difference between two test scores was calculated as Sdiff=2×5.642=7.97. Using Sdiff, RCI values were generated to identify the minimum necessary change in PCL-5 scores needed to achieve RCI values ≥ 1.96. Using this procedure, PCL-5 change scores ≥ 16 produced RCI values ≥ 1.96. Accordingly, sudden gains were identified as instances of reduction of at least 16 points on the PCL-5. This was assessed for the 5 sessions of WET and the 12 sessions of CPT, or the number of available sessions for those participants who prematurely dropped out of treatment. The second requirement is that the magnitude of the gain should be large compared with the pregain symptom severity, at least a 25% reduction of the pregain session PCL-5 score. The third, and final, requirement is that the magnitude of the gain should be large relative to symptom fluctuations before and after the sudden gain (Tang & DeRubeis, 1999). This is determined by comparing the mean score of the three pre-gain sessions to the mean score of the gain session and two post-gain sessions. We did not use this criterion because it was not feasible because WET only includes five sessions.2 Nevertheless, as stability of sudden gains is important, we did evaluate reversal of sudden gains, which Tang and DeRubeis define an increase of reported symptoms of at least 50% of the original improvement of the sudden gain. Relatedly, a sudden gain was not counted if it occurred in the last treatment session, as stability of the gain could not be evaluated, and it was not temporally separated from posttreatment outcome.

We used multilevel modeling (MLM), conducted in R (R Core Team, 2017), to test the effect of sudden gains on changes in PTSD symptoms over time in each condition. Analyses were conducted using all data points for all randomized participants (intent-to-treat analysis). The dependent variable was CAPS-5 total score. Models included a piecewise analysis of time; one linear time variable was created to capture th e slope of change during the treatment phase (baseline to week 24) and a second linear time variable was created to capture the slope of change during the follow-up phase (week 24 to week 60). Each of these linear variables was multiplied by dichotomous sudden gain status (time*sudden gain) in the model to assess whether experiencing a sudden gain was associated with a different rate of change during either period.

As mentioned previously, several baseline variables were examined as potential predictors of sudden gains. Specifically, sudden gain status as a dichotomous variable (0,1) was regressed on participant age, baseline CAPS-5 total score, BDI-II total score, and WTAR estimated FSIQ using logistic regression. Similarly, sudden gain status was also regressed on the CHANGE variables (negative view of self, negative view of others, and negative emotion) coded in the initial narrative from each of the treatment conditions.

Results

Occurrence of Sudden Gains

In accordance with the first requirement for establishing the presence of sudden gains, reductions of at least 16 points on the PCL-5, was observed in 45 of the 700 (6.4%) between-session intervals across both treatments. After evaluating if the magnitude of symptom reductions exceeded 25% of the pre-gain score (the second requirement for determining the presence of sudden gains), all 45 sudden gains remained. Next, in accordance with the third requirement, we examined the stability and/or reversal of gains and found that 26 of 45 (59%) potential observations remained. Overall, a total of 26 sudden gains that were large, rapid, and stable were exhibited by 24 of the 126 (19%) clients. The average magnitude of the sudden gain was 21.5 points on the PCL-5 (SD = 5.5).

Sudden gains in WET versus CPT

Comparing treatments, 13 of the 63 (20.6%) participants randomized to WET and 11 of the 63 (17.5%) participants randomized to CPT experienced sudden gains. The number of sudden gains that occurred did not significantly differ by treatment (t(25) = 0.49, p = 0.62). In WET, the 13 clients with sudden gains experienced only one gain, which is not surprising given brevity of the treatment protocol. In CPT, nine clients experienced only one sudden gain, and two clients experienced two sudden gains.

The treatment conditions did not differ significantly in terms of magnitude of sudden gains (t(22) = 0.66, p = 0.52), with an average magnitude of 22.23 points on the PCL-5 (SD = 6.1) for the WET condition and 20.73 (SD = 4.9) for the CPT condition. On average, sudden gains occurred at either session 2 or 3 (M = 2.69; SD = 0.75) in the WET condition and between session 5 and 6 (M = 5.64; SD = 3.0) in the CPT condition.

Sudden Gains and Treatment Outcome

As displayed in Figure 1, for both the WET and CPT conditions, the presence of a sudden gain was associated with a faster rate of decrease in PTSD symptom severity through 24 weeks (WET: B=−4.37, SE=1.12, t=−3.92, p<.001; CPT: B=−4.42, SE=1.60, t=−2.76, p=.008). These beta estimates represent a substantially faster rate of decrease in PTSD symptoms for each condition (linear time effect during the treatment phase in WET: B=−2.51, SE=0.51, t=−4.97, p<.001; CPT: B=−4.52, SE=0.69, t=−6.57, p<.001), indicating that those individuals who experienced sudden gains during treatment had a rate of change across the initial 24 weeks that was double or triple the rate of those who did not have a sudden gain. There was not a significant interaction of sudden gains with slope of change during the follow-up period in either condition (WET: B=3.15, SE=1.78, t=1.77, p=.082; CPT: B=3.01, SE=1.81, t=1.66, p=.100).

Figure 1.

Figure 1.

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Clinician Administered PTSD Scale for DSM-5 total scores for participants who did and did not experience sudden gains in each condition in written exposure therapy (top panel) and cognitive processing therapy (bottom panel).

Predictors of Sudden Gains

For participants who received CPT, age (B=0.02, SE=0.02, p=.45), CAPS-5 total scores (B=−0.01, SE=0.03, p=.97), BDI-II total scores (B=0.02, SE=0.03, p=.43), and WTAR estimated FSIQ (B=0.03, SE=0.03, p=.34) did not significantly predict who experienced sudden gains in treatment. Similarly, in WET, age (B=−0.03, SE=0.02, p=.24), CAPS-5 total scores (B=0.04, SE=0.04, p=.25), BDI-II total scores (B=0.02, SE=0.03, p=.60), and WTAR estimated FSIQ (B=0.02, SE=0.03, p=.53) did not significantly predict sudden gain status.

The CHANGE variables (negative view of self, negative view of others, negative emotion) expressed in the written narratives were also examined as predictors of sudden gains in each condition (see Table 1). In both the CPT and WET conditions, more expression of negative emotion in the initial narrative predicted the occurrence of a sudden gain. Neither of the cognitive variables were significant predictors.

Table 1.

Multiple logistic regression models examining narrative variables as predictors of sudden gain status

Sample B (SE) Wald p OR 95% CI
 Model χ2 R 2
 Predictor Lower Upper
WET (n = 61) 7.84* .20
 Negative View of Self 0.17 (0.50) 1.26 .73 1.19 0.45 3.18
 Negative View of Others −0.22 (0.37) 0.35 .56 0.80 0.39 1.67
 Negative Emotion 1.05 (0.45) 5.33 .02* 2.85 1.17 6.94
CPT (n=49)
 Negative View of Self −0.16 (0.42) 0.15 .70 0.85 0.37 1.93 7.09 .21
 Negative View of Others 0.58 (0.47) 1.51 .22 1.79 0.71 4.53
 Negative Emotion 1.39 (0.61) 5.22 .02* 4.02 1.22 13.26
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Note. Narrative variables were entered simultaneously as predictors of sudden gain status (0, 1) in multiple logistic regression models for each treatment condition separately. WET=written exposure therapy; CPT=cognitive processing therapy. SE = Standard Error, OR = Odds Ratio or Exponentiated B, CI = Confidence Interval, R2 = Nagelkerke R2

*

p < .05

Discussion

This study examined the sudden gain pattern of symptom change in two treatments for PTSD, WET and CPT. We investigated the sudden gains pattern as a predictor of treatment outcomes and also negative view of self and others and negative emotion in the first narratives as predictors of sudden gains.

Consistent with other PTSD treatment studies (Kelly et al., 2009; Konig et al., 2014), we found that sudden gains do occur among some individuals who receive CPT. Although WET is considerably briefer than CPT (five sessions compared to 12 sessions), sudden gains also occurred among some individuals who receive this treatment, and the gains did not differ in the number or magnitude from the gains of those who received CPT. In addition, sudden gains predicted greater improvement in PTSD symptoms across the course of both treatments. Together, this pattern of findings suggests that trauma recounting and processing delivered in various forms (e.g., prolonged exposure, CPT, WET) might not only facilitate improvement in posttreatment outcomes (e.g., Asnaani et al., 2016; Wisco et al., 2016), but also facilitate early sudden gains in PTSD symptoms.

Although the sudden gain pattern has been identified as a robust predictor of outcome across a range of treatments and clinical disorders (Shalom & Aderka, 2020), very little is known about what occurs in treatment that might facilitate these gains in treatments for PTSD. Both WET and the original CPT protocol include written trauma narrative exercises as part of the treatment, and these provide valuable information about how clients express their traumatic experiences early in treatment. We coded the content of the first narratives to assure that they preceded and did not follow the sudden gains that occurred. It is important to note, however, that does not assure that the narrative immediately preceded the specific sudden gain session for each person. A future direction might be to examine the sudden gain as a predictor of outcomes in the context of other types of symptom trajectories, such as linear and quadratic change and symptom variability (e.g., Andrews et al., 2020).

The activation of negative emotions is viewed as critical when recounting traumatic events and facilitating cognitive and emotional processing of those experiences (Asnaani et al., 2016; Resick et al. 2017; Sloan et al., 2007). In addition, there is some evidence that “putting words to feelings” (also called affect labeling) can facilitate the effects of exposure and extinction learning (Lieberman et al., 2007; Tabibnia et al., 2008). Consistent with this, we found that more expression of negative emotion in the first written narrative predicted the occurrence of sudden gains in both WET and CPT.

More expression of negative emotions might not only reflect activation of relevant fear or trauma networks (Hughes & Shin, 2011), but also better treatment engagement. Expressing more negative emotion might indicate a client’s ability to fully lean into the recounting of their trauma memory, which is associated with better PTSD treatment outcomes (Asnaani et al., 2016; Wisco et al., 2016). Related to this, we found in another study of this treatment trial that more negative emotion in CPT narratives also predicted less dropout (Alpert et al., 2020). The level of emotional engagement in early narratives can be assessed easily by clinicians in the beginning stages of trauma-focused treatment and could perhaps point to ways to enhance treatment engagement, reduce the risk of dropout, and improve treatment outcomes. However, a number of clients (56%) reported that the reason for dropout in CPT was that they found the treatment too distressing (Sloan et al., 2018). It might therefore be useful to examine whether there is an optimal level of emotional engagement that is not too low or too high (Foa et al., 2007).

Negative beliefs about the self and others expressed in the first narrative did not predict sudden gains in WET or CPT. Because we coded the first narrative, we could only examine level of negative beliefs and not change in those beliefs. It is possible that improvement in these negative beliefs predict sudden gains more than absolute level, as reported by Weideman et al. (2020) in cognitive therapy for PTSD. Given the importance of cognitive change across treatments for PTSD (Kleim et al., 2013; Kumpula et al., 2017; McLean et al., 2015; Schumm et al., 2015; Zalta et al., 2014), it might be useful to examine changes in negative views of self and others across the course of treatment rather than at one cross section at the beginning of treatment.

Although the current study found that sudden gains occurred in both WET and CPT and predicted PTSD outcomes, the percentage of individuals with sudden gains was notably less than what has been observed in other PTSD treatment studies (19% in this study vs. 23%−52% in other studies, with the exception of Haugen et al. (2015) who also reported sudden gains of 19%). The lower percentage of sudden gains in the current study is likely related to the higher score needed to meet the first of Tang and DeRubeis’ (1999) sudden gain criteria, which is based on the reliable change index (RCI). The RCI indicated that a reduction of at least 16 points on the PCL-5 was required to meet the first sudden gain criterion in this study. The possible score range on the PCL-5 is 0–80, and the cut score for probable PTSD diagnosis is 33 (Bovin et al., 2016); thus, a reduction of 16 points is quite large and nearly equivalent to the amount of change expected over an entire course of treatment (e.g., Resick et al., 2017). A reduction of 16 points on the PCL-5 is 20% of the PCL-5 total score range, which is substantially larger than the amount of change required for the first criterion in other studies that use different measures of PTSD. For example, Aderka et al. (2011) used a score that represented 7.8% of the total score range of the Child PTSD Symptom Scale (Foa et al., 2001), Kelly and colleagues (2009) used a score that represented 8.1% of the total scale range on the Posttraumatic Stress Diagnostic Scale (Foa et al., 1997), and Jun et al. (2013) used a score that represented 10.1% of the total score range on the PTSD Symptom Scale Self-Report (Foa et al., 1993). It is therefore difficult to compare the percentages of individuals with sudden gains across studies because of differences in the PTSD symptom measures and how that affects the RCI. This might, in part, account for the lower percentage of sudden gains reported in this study.

The current study had a number of strengths, including the relatively large sample size in the clinical trial, the examination of possible sudden gains at every treatment session rather than every other session (e.g., Kelly et al. 2009), and the use of a structured semi-structured clinical interview to assess PTSD treatment outcome. This is also the first study to our knowledge to examine narrative content to predict the occurrence of sudden gains in treatments for PTSD. These findings can apply to trauma-focused treatments in general, but especially to those that include trauma narratives, such as WET, CPT, narrative exposure therapy (NET; Schauer et al., 2011), and trauma-focused CBT (TF-CBT; Cohen et al., 2012).

There are also some limitations to consider. The rate of dropout was substantially higher for those in CPT (36.6%) than in WET (6.3%). However, all participants who had initial narratives were included in the current analyses, whether or not they dropped out. There were also no pretreatment differences (e.g., demographic, baseline PTSD symptom severity) between participants with and without narratives. An additional limitation is that the current study did not use the Tang and DeRubeis (1999) sudden gains criterion that compares the symptoms scores for the three sessions before and two sessions after the sudden gain because this was not possible with a five-session treatment (WET). When this original criterion was used for the CPT condition, we only found one less sudden gain occurrence, and this was for a participant who experienced two sudden gains. Thus, the modified and original criteria yielded the same number of participants with gains in CPT. Moreover, we did examine the session before the gain to ensure a 25% reduction in symptom severity (in addition to the 16-point criterion), and we required at least one session following the sudden gain to ensure that reversal of the sudden gain did not occur. Taken together, the slightly modified original sudden gains criterion is unlikely to have substantially impacted the findings reported here. The low percentage of participants with sudden gains (19%) in this study also reduced power for our exploratory analyses on possible predictors of these gains. These cognitive and emotional expression variables should be examined in samples with higer percentages of sudden gains. Another issue to consider is that narratives are assigned at fixed points during the treatment, so they cannot be linked precisely with the sudden gains. Future studies could code the content of the therapy sessions that immediately precede a sudden gain for a specific individual and for matched participants who do not experience a gain. Relatedly, future studies should consider including comparisons of post-treatment or follow-up scores between individuals who experienced a sudden gain and those who showed an equivalent magnitude of change over the same time period, but no sudden gain pattern. This approach would more directly test whether the timing of change in treatment is impactful beyond the mere magnitude of change.

Sudden gains are a clinically important phenomenon. They represent a period of rapid, meaningful symptom reduction during treatment that can be motivating to clients and clinicians. Additionally, our findings suggest that sudden gains are associated with more rapid reductions in symptoms as treatment progresses in both WET and CPT, a pattern that Tang and DeRubies (1999) suggested may induce an upward spiral of continued change. Our results also highlight the importance of emotional expression in early trauma narratives, which predicted sudden gains in both treatments. Clinicians may be able to use this information to facilitate more rapid improvements among their clients by encouraging emotional expression in the trauma narratives. This could be a simple and powerful clinical tool for enhancing treatment effectiveness and increasing buy-in for exposure and processing of traumatic experiences.

Highlights.

  • Sudden treatment gains in posttraumatic stress symptoms was examined

  • Sudden gains occurred in both treatment conditions

  • Patients who displayed sudden gains had better treatment outcome

  • Expressing more negative emotion in trauma narratives predicted sudden gains

  • Sudden gains may be helpful in predicting individual trauma-focused treatment response

Acknowledgments

The study was funded by a grant from the National Institute of Mental Health (MH095737) awarded to the first author. Dr. Thompson-Hollands was supported by a Career Development Award from Department of Veterans Affairs (# IK2 CX001589).

Footnotes

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1

Resick and colleagues (2017) now use the term CPT to refer to the modified version and use CPT plus written accounts to refer to the previous version of the treatment. The current study used the full CPT protocol; for clarity, we will use the term CPT to refer to the protocol version that includes the written accounts.

2

We used the original criterion definition for the CPT condition and found just one fewer instance of sudden gain was observed using the modified criteria. However, this instance was for a participant who had two sudden gains. Thus, the same number of participants had sudden gains using the original and modified criteria. Because the difference did not affect any of the findings, we only report sudden gains using the modified criteria.

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