A Developmental Examination of Pain Among Youth with Sickle Cell Disease

Introduction: Sickle cell disease (SCD) related pain is a difficult and challenging clinical problem that has significant negative effects on youth's health-related quality of life (Dampier et al., 2010; Walco & Dampier, 1990). Proper assessment and management of pain in the pediatric population is essential to both improving wellbeing of youth with SCD, and minimizing the development of chronic pain as patients transition into adulthood. Much of the previous research on pain among youth with SCD, however, has been limited by small sample sizes, lack of comprehensive pain assessment, and failure to examine developmental differences in pain across age groups. The current study aimed to compare the expression of pain and pain interference across four developmental stages: toddlers/preschoolers (2-4 years), school-aged children (5-7 years), preadolescents (8-12 years), and adolescents (13-18 years), utilizing both parent and youth reports as appropriate (i.e., school-aged and older). We hypothesized that pain and pain interference would generally be greater among older developmental groups.

Methods: The study sample included 386 youth with SCD and their parents who participated in the Sickle Cell Clinical Research and Intervention Program (SCCRIP), a longitudinal lifetime cohort study designed to examine change in health outcomes in SCD. Within SCCRIP evaluations, the Pediatric Quality of Life Inventory Sickle Cell Disease module (PedsQL; Panepinto, Torres, & Varni, 2012) is used to measure health-related quality of life including pain and pain interference. We examined the 2 pain-related subscale outcomes within the PedsQL: the Pain and Hurt and Pain Impact subscale scores in all four developmental groups. Multivariate analyses of variance (MANOVAs) were first conducted to compare, within each age group, youth- and parent-reported pain and pain interference separately. Two sample t-test or Wilcoxon rank sum test and its extended ANOVA or Kruskal-Wallis tests were then used to compare these variables depending on the normality of the data, in any two and multiple groups, respectively. Benjamini & Hochberg method was used to adjust for multiple comparisons to control for false discovery rate at an alpha level of 0.05.

Results: Gender and genotype were comparable across the four developmental groups. The proportions of patient exposure to disease-modifying therapy significantly increased by developmental stage: toddler/preschool =0.50, school-aged children =0.65, preadolescents =0.63, and adolescents =0.75 (p= 0.009). Parent-reports of child pain and pain interference gradually decreased from toddlers/preschoolers to school-aged children, and then from school-aged children to preadolescents (p s ranging from <.001 to .01), but no change was observed from preadolescents to adolescents. Similarly, youth-reported pain interference gradually decreased from school-aged children to preadolescents (p= .01), and from school-aged children to adolescents (p=.035), but no change was observed from preadolescents to adolescents. No significant change in youth-reported pain was observed across developmental groups.

Conclusions: The current study is the first, to our knowledge, to examine developmental differences in pain from toddlerhood to adolescence among youth with all SCD genotypes. Contrary to our hypothesis, parent- and youth-reported pain and pain interference did not increase across developmental groups, but instead tended to decrease across younger developmental groups, and appeared to plateau approaching adolescence. This latter finding is in contrast to previous research examining similar developmental groups in youth with SCD, where increasing youth-reported pain interference was observed from childhood (8-11 years) to adolescence (12-17 years; Dampier et al., 2016). The reason for the lack of increased pain and pain interference across developmental stages is unclear, but could be partially attributed to factors such as greater exposure to disease-modifying therapy by developmental group in the current sample. Future validation of these findings is warranted.