This is the first study to investigate possible predictors and moderators of outcome among the three most commonly employed treatment approaches for pediatric OCD: CBT alone, an SSRI (sertraline) alone, and their combination. Youth entering treatment with lower OCD severity, less OCD-related functional impairment, greater insight, fewer comorbid externalizing symptoms, and lower level of family accommodation showed greater improvement regardless of treatment assignment. Family history of OCD in a first-degree relative functioned as a moderator of treatment outcome.
All measures related to OCD severity were predictors of outcome. When conceptualized in terms of OCD-related functional impairment, our result replicates the findings of Piacentini and colleagues45
who reported that school-based functional impairment was a predictor of outcome in a CBT open trial. Although it differs from many previous controlled medication trials with children46–49
and CBT trials with medicated and unmediated adults,50
in the present study, baseline OCD symptom severity predicted worse outcome across all treatment conditions in our study. In two adult trials that also found this relationship,51, 52
they were able to demonstrate that people continued to benefit from exposure sessions during a follow-up phase. Therefore, our findings suggest that patients with more severe OCD may need additional sessions relative to their peers with more mild or moderate symptoms, either via a longer course of treatment than the 12 weeks (14 sessions) of therapy under investigation in this study, or via more sessions delivered within the 12-week period (e.g., twice-weekly).
Patients with higher levels of externalizing symptoms fared worse across all treatment conditions relative to their peers with lower levels of externalizing symptoms. Previous studies have reported similar findings.53,54
The lack of significant findings for diagnosis-level data is attributed to a lack of statistical power. A relatively small number of POTS patients met the threshold for an externalizing disorder (n=25 total, of which n=17 ADHD, n=7 ODD, and n=1 CD). Therefore, it is also not surprising that the two methods of examining the impact of externalizing problems in the present study (diagnosis versus symptoms) produced different results. When the Conners Global Index score was broken down into more narrow-band externalizing subscales, all subscales produced results consistent with the “omnibus” finding for the broad-band measure. These results suggest that the presence of elevated levels of externalizing symptoms interferes with the efficacy of the treatments in targeting OCD symptoms. This interpretation may indicate that children with comorbid externalizing issues require additional treatment components that address these issues. Future research should not only examine the efficacy of these additional treatment components but also in what sequence these additional components should be presented for youth with comorbid externalizing issues and OCD.
The negative findings for all of the demographics variables indicate that the effects of treatment are consistent and that these treatments can be used with a broad array of youth with OCD. We were unable to examine race and ethnicity as a predictor or moderator due to the low rate (8%) of non-Caucasian subjects enrolled. Therefore, caution is needed in generalizing the findings to diverse racial and ethnic groups, which is an important area for future research.
The absence of findings for the demographic variables is consistent with the majority of studies in pediatric OCD, and is reflected in Ginsburg and colleagues conclusion that gender and age are not associated with treatment response.6
However, it is different from results of moderator analyses of the MTA and TADS studies, both of which found socioeconomic status variables to be related to outcome. In the MTA study, those with more educated parents did better in combined treatment than in medication management alone.55
In the TADS study, youth from high-income families, which also tended to be more highly educated, fared relatively better in CBT-containing conditions.13
These results point to the need to examine parental education level as a potential moderator of treatment outcome in future studies of pediatric OCD.
Findings regarding family factors were perhaps the most intriguing to emerge from these analyses. Two of the four family factors variables were associated with outcome. Family history of OCD moderated outcome. The six-fold difference in effect size for monotherapy CBT for those with and without a family history is particularly striking. A family history of OCD could attenuate CBT due to the fact that treatment involving EX/RP may require more family support than medication compliance. For example, parents and other families are often asked to assist the child at home with CBT tasks such as symptom monitoring and EX/RP homework. For parents who have OCD or have immediate family members with OCD, these activities are likely more difficult than simply monitoring medication compliance. It appears that COMB was more robust to these issues in that there was a less marked difference in effect size (2.5-fold). The clinical implications of these findings are that perhaps those with a family history of OCD should be offered CBT only in combination with medication. Replication of these results would be necessary before such a recommendation should be codified.
Although there was no evidence of a relationship between broad-based family dysfunction or parental psychopathology and treatment outcome, a more specific measure of family functioning was associated with outcome. Higher levels of family accommodation were associated with poorer treatment outcome across treatment conditions. Complementary findings have been reported elsewhere in that decreases in family accommodation predicted improvement in family-based CBT that targeted accommodation.56
The CBT delivered in this study allowed other family members to participate in sessions as needed, but it was not conceptualized as a family-based treatment. These results suggest that when levels of accommodation are high, more family work and explicit focus on reducing accommodation may be warranted. It is possible that there is a link between accommodation and family history. Although the present study was underpowered to identify moderation controlling for covariates, it is possible that there is a functional influence between family history of OCD and accommodation of OCD.
These results must be understood in the context of several limitations. First, although one of the largest randomized samples pediatric OCD, the study was not powered adequately to examine questions of moderators across 4 treatment conditions. Therefore, the absence of findings should not be taken as findings of absence. We consider this work exploratory and hypothesis generating.
With one exception, nothing in the present report invalidates the conclusion of the primary paper3
that patients with OCD should start treatment with either CBT or CBT + medication. Specifically for those with a family history of OCD, CBT with E/RP appears to be dramatically hindered unless augmented with SSRI treatment. The present results also suggest specific groups of patients for whom the standard treatment approaches may be less efficacious. Specifically, the present results suggest the need for further examination of the following: longer duration than 12 weeks of treatment or more intensive visit schedule for those with more severe symptoms, augmentation strategies (either pharmacological or psychotherapies) that target externalizing symptoms, and family-based treatment strategies that address the fact that more than one family member may be affected by OCD and can address high levels of family accommodation. Future work will be able to address whether the specific predictors and moderator identified in the present study convey to other samples of youth with OCD.