Pediatric obsessive–compulsive disorder (OCD) is a debilitating psychological condition associated with deterioration of functioning in social, scholastic, and family activities (1). Several studies report early-onset OCD, indicating that for various reasons children are often underdiagnosed. Some reasons are that the child/adolescent hides the worries and rituals due to the low intensity of the discomfort. In addition, parents often believe that worries and rituals are fleeting (2, 3). On the other hand, a high percentage of adults with OCD admit to having begun suffering alterations in childhood or adolescence (2).

Recent studies have estimated the prevalence of OCD among children to be close to 3% (4). OCD in childhood/adolescence usually occurs together with other comorbidities, increasing the degree of discomfort and complicating prognosis and response to treatment (5). Several studies have found high rates of comorbidity, with percentages ranging from 50 to 80% (6). The most common associated disorders are anxiety disorders (26–75%), mood disorders (25–62%), tics (20–30%), attention-deficit/hyperactivity disorder (10–50%), and disruptive behavior (18–33%) (2, 7–9).

Treatment options for children with OCD include cognitive–behavioral therapy (CBT), pharmacotherapy, or both (2, 10). The American Academy of Child and Adolescent Psychiatry Committee on Quality Issues (2) considers that the standard of care in very young children with OCD is cognitive–behavioral family-based treatment (CBFT), which includes the same core components of CBT with significant family involvement. Parental involvement has shown to be a predictor relevant to improve the benefits of CBT in reducing obsessive–compulsive symptoms (11), whereas others showed that CBT for pediatric OCD is effective when delivered in different formats and that the active involvement of parents is not a crucial factor for the treatment effects (12).

Although family CBT reports high rates of remission, some children do not adequately respond to treatment to these first-line treatments, highlighting the need to identify predictors of poor response, such as comorbidity, baseline OCD severity, age at onset, parental psychopathology, behavior management skills (parental tools), family accommodation, etc. (13–16).

Predictor variables can be classified into eight broad classes (17, 18): (a) demographic variables; (b) characteristics of OCD symptoms such as severity; (c) comorbidity and associated symptom severity; (d) cognitive influences; (e) motivational factors such as treatment expectations; (f) treatment factors (e.g., compliance, therapeutic alliance); (g) biological factors; (h) other factors (e.g., family, treatment-specific characteristic).

A review of response predictors to CBT concluded there are inconsistencies in the literature (16). Therefore, this study focuses on three factors as these are considered relevant in the effectiveness of treatment of young children with OCD. These are comorbidity, initial severity, and father's and mother's accommodation.

Previous research found that pretreatment OCD severity was a negative moderator of treatment outcome, whereas comorbid anxiety was a positive moderator of treatment effect (12). Højgaard et al. (19) found that pretreatment OCD severity and levels of comorbid anxiety predict posttreatment OCD severity. However, when controlling for the effect of these predictors in a single model, only lower pretreatment OCD severity remained a significant, positive predictor of posttreatment OCD severity. Several studies showed that pretreatment OCD symptom severity significantly predicted posttreatment OCD outcome, and explained 20.6% of variance in posttreatment Yale–Brown Obsessive–Compulsive Scale (Y-BOCS) (20). Ginsburg et al. (21) showed that baseline severity of obsessive–compulsive symptoms and family dysfunction were associated with poorer response to CBT; also, comorbid tics and comorbid oppositional defiant disorder predicted poorer response to medication treatment. García et al. (22) reported that patients with higher levels of externalizing symptoms achieved worse results than those with low levels of these symptoms. Regarding depressive symptoms, some authors have found the presence of depression was not associated with a poorer response to treatment (23). Nevertheless, others showed that higher average OCD severity was associated with greater depressive symptoms across treatment but that regardless of initial depressive symptom severity, these decreased in line with reductions in OCD symptom severity (24). Other studies do not coincide with the above, concluding that pretreatment levels of symptom severity or presence of comorbidity predicted the outcome at posttreatment or at follow-up (16, 25).

Family accommodation (e.g., providing reassurance, providing items, assisting in avoidance, modifying routines) has also been studied as a predictor of response to treatment for several reasons. Mainly, high rates of accommodation among families of children with OCD suggest that up to 60–96% of relatives modify their family routines and even perform the child's rituals (22, 26–32). Second, the absence of or little introspection of minors can hinder involvement in treatment; also, the parents can participate as co-therapists and carry out exposure tasks at home, allowing us to come closer to ideal treatment as this contributes both to generalizing and maintaining achievements, and so on (5, 14, 33–36).

Some factors have been associated with parental accommodation, such as OCD symptom severity, functional impairment, child's internalizing and externalizing symptoms, parent psychopathology, and so on (5, 26–29, 36). In addition, it has been considered as a predictor of treatment outcomes (22, 37), although other studies were not found to predict outcome at posttreatment or at follow-up (25).

Given these discrepancies, the main aim of our study was to investigate the predictive factors of the initial accommodation of the father and mother of young children with OCD together with checking if accommodation and levels of externalizing disorders are variable mediators in the efficacy of treatment both at posttest and at follow-up at 6 months.

Analyzing separately the accommodation of each member of the couple is due to the fact that most studies have focused on only one involved parent (most commonly the mother) or clustered together different family members within the same study. Therefore, it would be interesting to analyze the differential response between family relatives to a child's OCD symptoms. Although focused on anxiety disorders, Thompson- Thompson-Hollands et al. (38) examined parental accommodation among mothers and fathers, concluding the mothers were slightly more accommodated than fathers. Focused on pediatric OCD, there are very few studies that have separately analyzed differences in father's and mother's accommodation. Futh et al. (39) found no differences between the two, whereas Monzani et al. (40) reported that mothers achieved significantly higher levels of accommodation than fathers. Both maternal and paternal accommodation significantly predicted worse treatment outcomes. In both studies, hierarchical analysis and regression were presented, reaching different results in children aged 7–18 years.

This research studies predictive factors in young children with OCD (5–8 years), it separately analyzes the accommodation of the father and mother, and it carries out an analysis of mediating variables of the efficacy of treatment in posttest and follow-up.

The specific objectives of the study were:

Pediatric OCD is a debilitating psychological condition associated with interference in child's recreational, academic, social, and family activities (1). Various studies have been conducted to enhance the efficacy of treatments and predictive variables (18, 22, 47). However, we are not aware of any study focused on the analysis of predictors and mediators of treatment in young children (5–8 years) with OCD.

One of the main aims of our study was to investigate the predictive factors of the initial mother's and father's accommodation of young children with OCD. Many researchers have studied family accommodation, reporting a high implication in the efficacy of treatment (22, 37). The age of our sample led us to suppose that parents would be highly accommodated with their children's rituals. These are young children whose main manifestation will be compulsions and rituals that will involve their parents. The results of the current study have indicated a high correlation between obsessive–compulsive responses and accommodation of the mother and father, consistent with previous studies (24, 39, 40). We have been able to observe that the mother's accommodation was greater than the father's, coinciding with the study of Monzani et al. (40), which might simply relate to the amount of time a caregiver spends with a child with OCD. The mothers spent a greater number of hours [mean = 10 (SD = 2.7) h] than the fathers [mean = 5 (SD = 4.58) h]. Furthermore, a high correlation between accommodation mother and father scores was also observed, suggesting that if one parent accommodates a child's symptoms, the other seems more likely to do so as well.

The results of the hierarchical regression analysis indicated that the mother's accommodation could be predicted according to the child variables CBCL-externalizing and initial OCD severity (CY-BOCS pretest), whereas the father's accommodation could be better explained by variables mother's accommodation and father's worry. The results of the mother's accommodation coincide with those indicated by Caporino et al. (26), although the percentage of variance explained in our study was higher (68.7%).

The externalizing symptoms of the child would be the main predictor explaining 59% of variance. Children who present externalizing symptoms can cause family conflict, difficulty in the relationship with parents, punishments, and so on, being more resistant in carrying out treatment. Parents' abilities to manage their children's disruptive behaviors would be an important variable when it comes to better understanding the efficacy of treatment. This result is in line with other research as mothers accommodate themselves in order to avoid the child's problem behaviors, thus increasing the child's compulsive behaviors (40). In addition, the severity symptoms obsessive–compulsive predicted maternal accommodation, being somewhat expected and coinciding with that reported in previous studies (5, 7, 51, 52). Therefore, mothers of children with greater behavioral problems and greater severity of the disorder will present greater accommodation. Therefore, externalizing problems and comorbidity with externalizing disorders must be taken into account when carrying out treatment in children with OCD. In addition, the severity symptoms obsessive–compulsive predicted maternal accommodation, being somewhat expected and coinciding with that reported in previous studies (5, 7, 51, 52). Therefore, mothers of children with greater behavior problems and greater severity of the disorder will present greater accommodation.

Father's accommodation was not explained by the severity of the obsessive–compulsive behaviors but by the mother's accommodation and the father's worry. The percentage explained by both predictors was lower (35.4%). One possible explanation is that the mother's coping responses influence the way in which the father intervenes with the child when obsessive–compulsive responses occur. This could be due to the fact that the mother spends most of the time with the child, producing the main changes. On the other hand, parents with greater worry and anxiety increased their accommodation responses, as these temporarily reduced the fear and worry. This result is in line with that reported by Monzani et al. (40) in which father's distress was associated with mother's accommodation. These results would inform a circle that would maintain and enhance maintenance of the child's problem responses (26).

Another of our aims was to study whether the variables parental accommodation and externalizing disorders would be mediating variables between initial severity and externalizing symptoms, which were mediators between the initial and posttest severity levels, although the value of the coefficient was small. Similarly, these problems mediated results at follow-up. This result emphasized the importance of comorbidities, specifically externalizing symptoms, in treatment results, consistent with previous research (21, 22). In addition, our results highlight the potential value of screening and providing additional support for parents of children with obsessive disorders and externalizing symptoms in order to adapt treatment to both types of symptoms.

Mother's accommodation was not a mediating factor between initial severity and posttreatment and follow-up severity. Its relationship with severity pretreatment and posttreatment was observed, but could not be considered a mediator in improvement after intervention. This indicates that the main moderator to take into account to reduce obsessive–compulsive symptoms was the external symptoms of the child. Therefore, it is necessary to train in this type of problem to improve obsessive–compulsive symptoms (5, 51).

Clinical implications of this study are the need to take into account not only mothers in treatment but also fathers as they can be indirectly influenced. We can conclude that the comorbidities of externalizing symptoms, the father's worry, and the mother's accommodation are variables that we should control for when performing a treatment in pediatric OCD. Emerging evidence supports the benefits of family-based CBT, incorporating treatment modules that address externalizing symptoms and family accommodation. Sukhodolsky et al. (53) analyzed the importance of including the intervention together with the ERP training for parents in the management of disruptive behaviors, achieving greater improvement when both strategies were combined in children with secondary diagnosis of problems of conduct. Rosa-Alcázar et al. (49) indicated that the involvement of both parents in the child's treatment showed statistically significant differences in internalizing and externalizing symptoms and mother's and father's accommodation.

There are several study limitations. First, the small sample size limits the generalizability of our results. Second, follow-up outcomes are insufficient; that is, they have a provisional nature, and follow-up is required at 12 and 24 months to more rigorously assess the scope of achievement stability. Third, the study relied on parents as central informants, and no measures were in place to ensure that mothers' and fathers' responses were collected independently from the other parent. Finally, causality between accommodation and treatment response cannot be established from this study. More research is needed to confirm the direction of causation in order to inform intervention strategies.

Future research should examine not only the efficacy of these additional treatment components but also in what sequence these additional components should be presented for young people with OCD and comorbidity with externalizing symptoms, as indicated by other authors (22). The inclusion of more predictors, increasing the sample size, could help to better analyze the effects of mediation on treatment results in young children with OCD.

Notwithstanding these limitations, the analysis of the predictors of mother's and father's accommodation in the pretreatment together with the study of a mediation model to clarify the relationships between severity pretreatment and posttreatment/follow-up and externalizing symptoms and mother's accommodation is an important contribution to the pediatric OCD literature.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by Ethics Committee of Murcia University. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.

AR-A and ÁR-A: conceptualization. AR-A, ÁR-A, PO-O, JP-N, and ER-A: treatment, writing—original draft preparation, review, and editing. AR-A: methodology, formal analysis, data curation, and supervision. All authors have read and agreed to the published version of the manuscript.

This research is part of Project 20902/PI/18 financed by the Autonomous Community of Murcia (Spain) through the Grants for projects for the development of scientific and technical research by competitive groups, included in the Regional Program for the Promotion of Scientific and Technical Research (Action Plan 2018) of the Seneca Foundation-Science and Technology Agency of Murcia Region (Spain).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.