Pain-Specific Patient-Reported Outcomes Are Worse in Adults Compared to Children with Sickle Cell Disease

Acute and chronic pain are the most common complications of sickle cell disease (SCD). As children transition into young adulthood, SCD-related pain may change or worsen. While acute intermittent pain events are predominantly experienced by younger children, chronic pain emerges in adolescents and the prevalence of chronic pain increases with age. The ability to evaluate pain across the lifespan in SCD utilizing the same patient-reported outcome measure (PRO) is critical to understanding the SCD pain continuum as it progresses and evolves with age. To understand the impact of SCD pain across the lifespan, we sought to utilize pain-specific PROs to characterize pain in both pediatric and adult age groups. We hypothesized adults with SCD will have worse pain-specific PRO scores compared to children with SCD.

A cross-sectional single-institution study was conducted of pediatric and adult individuals with SCD during baseline state of health, defined as the absence of acute care utilization for at least 2 weeks prior to data collection. Individuals ≥8 years of age self-reported PROs using the Patient Reported Outcomes Measurement Information System (PROMIS). The specific measures completed were Pain Interference, Pain Behavior, Pain Intensity, and Global Health. PROMIS is a publicly available platform that includes validated PRO tools to evaluate physical, mental, and social health in children and adults. PROMIS measures are used in the general healthy population and in those living with a chronic illness. PROMIS uses a T-score metric in which 50 is the mean of the reference population and 10 is the standard deviation of that population. For the measures included in the study, higher scores indicate worse health. Pediatric T-scores generated from the PROMIS Pain Interference measure were converted to adult T-scores per the published conversion formula. Participants were classified into two groups: Pediatric (age 8-17.99 years) and Adult (≥18 years). The PROMIS Global Health measure was categorized into three groups: Excellent/Very Good, Good, and Fair/Poor. PRO scores were compared between the two age groups using t-test for T-scores and chi-square for proportions. Significance level was set at p<0.05.

A total of 79 individuals with SCD were included in the study cohort; 48 in the pediatric group and 31 in the adult group. For the pediatric group, mean age was 12 (SD=3) years and 43.8% (n=21) were female. For the adult group, mean age was 36 (SD=12) years and 54% (n=17) were female. Across the age groups, 70.8% (n=34) of children/adolescents and 48.4% (n=15) of adults had HbSS/Sβ⁰thal genotypes and 29.2% (n=14) of children/adolescents and 51.6% (n=16) of adults had HbSC/Sβ+thal genotypes. For all pain-specific PROMIS PROs, mean scores were significantly higher in adults as compared to the pediatric group. Specifically, adults had significantly higher mean scores on the Pain Interference (59.1 (SD 9.5) vs. 51.5 (SD 7.2), p=0.0001), Pain Behavior (58.5 (SD 9.3) vs. 37.9 (SD 12.8), p<0.0001), and Pain Intensity (4.4 (SD 2.8) vs. 2.1 (SD 2.6), p=0.0003) measures as compared to children/adolescents. There were also significant differences on the Global Health Measure between the adult and pediatric groups (overall p=0.0132). Specifically, a significantly higher proportion of adults reported their health as Fair/Poor as compared to the pediatric group (50.0% vs 18.8%, Bonferroni adjusted p = 0.001).

Pain-specific PROs are worse in adults with SCD compared to children and adolescents, indicating more impairment in pain-related functioning, a higher degree of external manifestation of pain, and increased pain intensity. Additionally, Global Health scores demonstrate adults with SCD view their overall health significantly worse as compared to children and adolescents. Our data also demonstrate that pain-specific PROs are valuable tools that can be utilized to assess SCD pain across the lifespan. Future SCD pain-related research is needed to investigate pain longitudinally in individuals across the lifespan. This future work is vital to capturing the critical period during the transition from adolescence to adulthood when chronic SCD pain begins to evolve.