The current study expands our understanding of factors associated with HRQOL in adolescents with IBD through the examination of demographic, physiological, and behavioral factors as correlates of HRQOL. Though demographic factors were not associated with HRQOL, important relationships between disease severity, behavioral dysfunction, and HRQOL were found. Consistent with prior findings, increased disease severity was associated with lower HRQOL. In addition, higher levels of externalizing symptoms were related to lower HRQOL. One possible explanation for this finding is that increased externalizing symptoms (e.g., aggression, delinquent behavior) may lead to increased negative experiences in school and social settings, which may reduce youth’s overall perception of HRQOL. An alternative hypothesis is that externalizing symptoms are a byproduct of adolescent coping with poorer HRQOL. Further investigation of this relationship is needed to understand how externalizing symptoms relate to HRQOL and if this relationship is bidirectional.
Internalizing symptoms emerged as a strong correlate of disease severity and predicted HRQOL. Among an adult IBD sample internalizing symptoms were found to independently contribute to lowered HRQOL.22
To our knowledge, however, this study is the first to report such a relationship in a pediatric population. The emergence of internalizing symptoms as the mechanism through which disease severity partially affects HRQOL adds significantly to our understanding of the disease severity-HRQOL relationship. Increased disease severity may directly impact quality of life through the increased presence of disruptive GI symptoms and the possible need for more aggressive treatment approaches (e.g., surgery, steroid treatment). Our partial mediation model suggests an additional pathway through which disease severity impacts HRQOL. Due to the unpredictable and disruptive nature of their disorder, adolescents with IBD may be more likely to experience internalizing symptoms (e.g., anxiety and depression), especially when their disease is most active and has the greatest potential to impair daily functioning. Increased levels of these internalizing symptoms may lead to further declines in reported HRQOL.
Results from the current study have direct implications for the design of intervention programs to improve HRQOL in adolescents with IBD. Though disease severity is a commonly targeted variable, our results suggest that it is also important to target symptoms of behavioral dysfunction. There is some evidence from the adult IBD literature to suggest that targeting psychiatric morbidity may lead to improvements in HRQOL.23
Although interventions targeting emotional and behavioral functioning have been reported in other pediatric chronic illness populations, only one psychosocial intervention has been reported in pediatric IBD.24
In this pilot study, adolescents with IBD and comorbid depression received an adapted 12-session cognitive-behavioral intervention. By the end of the intervention, adolescents reported a reduction in depressive symptoms and, although HRQOL was not specifically measured, adolescent perceptions of their general health and physical functioning had improved from pre- to post-treatment. Taken together, these studies provide some evidence to suggest that targeting behavioral symptoms as well as taking steps to improve an adolescent’s health status may optimize improvements in HRQOL. Targeting behavioral symptoms may also improve disease activity by either improving medication adherence or by reducing symptoms of fatigue and poor appetite, which are common in certain internalizing disorders but may be mistakenly interpreted as signs of increased disease activity.
The current study has several strengths including the use of well-validated measures to assess disease severity, behavioral dysfunction, and HRQOL, multi-site data collection, and the collection of data from multiple sources. The use of an IBD-specific HRQOL measure is a particular strength over previous research studies that have primarily utilized generic measures of HRQOL. Disease-specific measures have been found to be superior to generic measures as they have fewer ceiling effects and demonstrate more variability in scores, suggesting greater sensitivity to change in HRQOL.25
In addition, the collection of data from multiple sources limits shared method bias. Disease severity ratings were calculated using objective data including laboratory results and symptom frequency.
Nevertheless, this study is not without limitations. First, the cross-sectional nature of this study prohibits the inference of causal relationships. Additionally, though the mediation model presented met criteria for partial mediation according to the guidelines set forth by Baron and Kenny,21
the Sobel test was marginally non-significant. Thus, the significance of the indirect effect of disease severity on HRQOL via behavioral dysfunction could not be confirmed. However, this analysis may have been underpowered due to the conservative nature of the Sobel test, which assumes a large sample size.26
The relative homogeneity of the participant sample with regard to race, socioeconomic status, and disease severity is another limitation. Though the current sample is similar in demographic background to other samples previously reported in the literature,27
the extent to which our findings are generalizable to all adolescents with IBD, particularly those from lower socioeconomic status or from an ethnic minority background, is unknown.
Although participant disease severity varied, the majority of the sample was reported to have inactive or mild disease. By nature of its treatment, patients with severe disease may have been underrepresented in our study as they are typically treated in an inpatient setting and our study was conducted with an outpatient sample. Thus, our study captured the typical pattern of functioning of children and adolescents with IBD treated in an outpatient setting. It is unknown to what extent these findings generalize to the smaller percentage of patients with severe disease activity. Future studies utilizing recruitment within an inpatient unit may further articulate factors related to HRQOL that are unique to this subpopulation.
Data collection for the larger longitudinal study from which this cross-sectional data were drawn began prior to the publication of the Pediatric Ulcerative Colitis Activity Index28
, Thus, the disease severity measure for ulcerative colitis patients in this study may not be the most rigorously validated measure. The use of two separate measures, each with a different scale, to assess disease severity is another limitation. Though the use of two measures with a different scale was not ideal, this was the best approach to assess disease severity as IBD subtypes (UC vs. CD) differ in symptom presentation and are thus assessed differently with regard to disease severity. Additionally, given that higher scores on both measures were indicative of greater disease severity and regression analyses were used to examine if increases in disease severity corresponded to decreases in HRQOL, methodological issues associated with combining these two measures were minimized. Finally, this study was unable to account for overlap in symptoms (e.g., fatigue and depression) of internalizing disorders and disease activity. One possible solution to this problem would be to remove items on the YSR that overlap with physiological signs of disease activity. However, doing so would greatly compromise the construct validity of the YSR and subsequent study findings.
While the current study improves our understanding of the role of disease severity and behavioral dysfunction in IBD HRQOL, additional research is needed to advance our understanding of how these relationships change over time and in response to intervention. Effort should be made to identify factors related to treatment regimen demands that may be associated with HRQOL. Though the relationship between treatment burden and HRQOL has been documented among patients with cystic fibrosis,29
this relationship has not been examined in children and adolescents with IBD. Additionally, given the chronic, intermittent, and unpredictable nature of IBD, the relationship between illness uncertainty30
and HRQOL is also worthy of investigation, as increased level of illness uncertainty may lead to patient perceptions of lowered social, physical, and emotional functioning. Continued identification of key factors associated with HRQOL will not only improve our understanding of this complex construct, but will also inform the development of intervention programs to improve HRQOL and maximize patient outcomes.