We hypothesized the AS would demonstrate significant relationships with psychological well-being and social functioning but not with physical functioning in this sample of children with chronic pain. Consistent with our hypothesis, after controlling for key sociodemographic and pain-related characteristics, elevated AS was associated with poorer psychological well-being, i.e., worse perceived mental health, lower self-esteem, and more behavior problems, as well as poorer social functioning, i.e., greater limitations in family activities and an increased likelihood of social/academic limitations due to emotional problems. As hypothesized, AS was not related to physical functioning or to limitations in school work/activities with friends due to physical problems. Moreover, our exploratory analysis revealed that elevated AS was related to poorer perceived general health, explaining 11% of incremental variance. Overall, AS was found to contribute independently to children's HRQOL in all but two of the eight domains examined, accounting for 4% – 28% of incremental variance above and beyond the demographic and pain-related variables (see and ). AS accounted for the largest share of associated variance for the mental health domain, and AS was the only significant correlate of the behavior and role/social emotional domains. For general health and self-esteem, AS explained the second largest portion of associated variance after age; for family activities, AS explained the second largest amount of associated variance after race/ethnicity.
In contrast to previous work8, 14, 22, 24
, we found that pain-related characteristics, i.e., pain intensity, pain duration, and presence of multiple pain diagnoses, did not account for significant incremental variance in HRQOL after controlling for demographics. One possible explanation for this divergence relates to differences in pain assessment. Prior studies8, 14, 22
assessed pain characteristics using pain diaries; average pain intensity derived from pain diaries was found to be significantly lower than retrospectively estimated pain intensity from a single VAS score8
. The latter method of pain assessment was used in the current study. The diary method may therefore yield more accurate estimates of pain8
and should be employed in future research on HRQOL. Another possibility concerns differences in sample composition. In previous work with adolescents reporting various chronic/recurrent pain complaints, the extent of care-seeking was unclear8, 22
. Our sample consisted of children whose parents were seeking care for their child at a tertiary specialty clinic for the treatment of chronic pain. Typically, these patients were referred from subspecialty clinics, and all had at least one formal pain diagnosis. The current sample also reported considerable impairment as evidenced by CHQ scores which, for all subscales except for behavior, were significantly lower than normative values (see ). Moreover, the present sample reported lower
CHQ scores, indicating greater impairment in physical functioning and role functioning due to physical problems than children with end stage renal disease. It may be that pain characteristics in this highly impaired sample were more restricted in range compared with that reported in prior studies which included both care-seeking and non-care-seeking adolescents.
Our findings are consistent with previous research demonstrating the salience of psychosocial factors in HRQOL among children with chronic pain22
. Merlijn et al (2006)22
reported that vulnerability and emotion-focused coping were strongly associated with multiple domains of HRQOL. In contrast to the single subscale assessing social functioning in the Merlijn study, the CHQ includes three subscales assessing social/academic limitations due to physical health, emotional problems, and behavioral problems. As noted above, AS was not associated with the physical health dimension and we did not examine the behavioral dimension since 75%+ of children reported no such limitations due to behavioral problems. For limitations due to emotional problems, our overall model explained 22% of the variance in group membership (high vs. low impairment). Notably, AS emerged as the only significant correlate with a 1 unit increase in AS increasing the likelihood of being in high impairment group by 1.18 units (see ). These findings together with those indicating a significant link between AS and limitations in family activities suggest that elevated AS is associated with disruptions in social functioning both at home and at school.
Although AS was primarily related to psychological aspects of HRQOL, AS also accounted for significant incremental variance in perceived general health. Because prior work has not investigated the association between AS and general health perceptions, the factors that may modulate this link are unclear. As noted above, contrary to the fear-avoidance model2, 3
which holds that AS enhances the fear of pain which in turn amplifies pain-related avoidance, Plehn et al. (1998)27
did not find significant associations between AS and physical functioning in their adult study. We replicated these negative findings suggesting that the relationship between AS and perceived general health may be independent of children's ability to engage in physical activities. Although reasons for our null findings are unclear, as discussed above, CHQ scores for physical functioning and role functioning due to physical problems in our sample were significantly lower compared to children with end stage renal disease. Thus, in this severely impaired sample, physical functioning appears to be influenced by other factors not measured in this study.
Our analysis revealed significant relationships between demographic characteristics and HRQOL. Older age was associated with poorer perceived general and mental health, and lower self-esteem—findings that are largely comparable with studies of school children12
and children with chronic pain11
. We also found that non-Caucasian children reported fewer limitations in family activities and better perceived mental health than Caucasian children. Studies to date have not examined the impact of race/ethnicity on HRQOL in chronic pediatric pain, most likely because the majority of patients in tertiary pediatric pain clinics are Caucasian. Even in our sample, wherein roughly 30% were non-Caucasian, we were not able to examine individual racial/ethnic categories due to small cell sizes. The role of cultural influences in children's HRQOL warrants additional study.
Limitations to our findings should be mentioned. First, we did not collect other measures of psychological symptoms and thus could not assess the relative strength of the association between AS and HRQOL taking into account other psychological symptoms. Nevertheless, in additional analyses controlling for the presence of possible anxiety disorder as assessed by the evaluating physician at the initial intake and noted in the patient's medical chart, AS retained its significant association with all of the CHQ domains except for family activities. Moreover, the amount of incremental variance explained by AS did not change substantially in these analyses (general health: 10%; self-esteem: 5%; mental health: 21%; behavior: 26%). Although the assessment of possible anxiety disorder was not made using an established clinical interview measure and thus reliability could not be ascertained, all children were asked about anxiety symptoms by the evaluating physician. Whereas clear relationships between psychological symptoms (e.g., depression) and functional impairment have reported9, 10, 16, 28, 38
, there are no existing investigations on the associations between such symptoms and multiple HRQOL domains in pediatric chronic pain. Moreover, trait anxiety was unrelated to functional disability in two studies28, 37
(although positive findings were also reported38
), suggesting that different psychological symptoms may have varying impacts on HRQOL.
Second, our assessment of HRQOL was based solely on child self-report. In preliminary analyses for the current study, we did not find significant associations between child AS and parent reported HRQOL. In their comprehensive review, Matza et al.19
concluded that due to conflicting results, it is not possible to provide an empirically based, conclusive answer as to whether the child or parent is best situated to assess the child's HRQOL. Further, Matza et al. stated that the use of child self-report is ideal, particularly with older children, since this approach is consistent with the definition of HRQOL which emphasizes individual's own subjective perspective19
. Nevertheless, our findings may be at least partially explained by the use of a single informant (i.e., the child) and shared method variance (i.e., questionnaires to assess both AS and HRQOL). Third, the amount of incremental variance explained by AS was relatively small for certain HRQOL domains. However, it should be noted that AS was associated with HRQOL above and beyond demographic and pain-related characteristics that have traditionally been thought to influence HRQOL. Finally, our study was cross-sectional and causality cannot be inferred. Additional longitudinal studies should examine whether elevated AS promotes long-term decrements in HRQOL among children with chronic pain.
Our findings suggest that clinicians may consider evaluating AS in children with chronic pain as part of a comprehensive assessment battery. As noted by Plehn et al. (1998)27
AS may play a key role in chronic pain since impairments in psychological well-being and social functioning may diminish treatment response and increase the likelihood of relapse. The inclusion of treatment components targeting AS may also lead to enhanced HRQOL in children. Recent work indicates that cognitive-behavioral therapy focused on reducing AS leads to significant reductions in pain-related anxiety in adult women with elevated AS39
. Understanding the complex links between AS and HRQOL may lead to the development of more targeted interventions aimed at improving the well-being of children with chronic pain.