Young Adults With SCD Show Better Hydroxyurea Adherence Than Children, Adolescents

Adherence to hydroxyurea (HU) treatment is low among patients with sickle cell disease (SCD) despite its effectiveness in reducing disease-related complications, which typically begin in early childhood. With adherence estimated at less than 50% in children, adolescents, and young adults, a study published in Annals of Medicine stresses the importance of identifying interventions to improve treatment adherence for patients with SCD receiving HU.

SCD is particularly prevalent in those of African descent, with an estimated 1 in 500 African American live births affected. The various complications associated with SCD impact health-related quality of life (HRQOL) for patients and have been found to produce higher rates of hospitalization among SCD patients versus the general population.

HU is the most commonly used first-line treatment for SCD, which is an inherited disease characterized by chronic anemia, vaso-occlusive pain episodes, acute chest syndrome, stroke, and other major organ damage. While newer agents have been FDA-approved, HU is cost-effective and has been shown to reduce complications and hospital visits for patients with SCD. It works by increasing fetal hemoglobin (HbF%) and is approved in both adults and children 2 years of age or older.

Reasons behind treatment HU non-adherence may include a fear of side effects, misconceptions about the medication, limited medication access, and limited communication with medical teams. However, few studies have explored treatment adherence in SCD among different age groups. The current study aimed to characterize HU adherence among children, adolescents, and young adults with SCD.

“We hypothesized that some patient characteristics would be associated with higher or lower HU adherence, in particular age,” the authors wrote. “We also hypothesized that higher HU adherence at different time points would be associated with lower health care utilization.”

The 5-year retrospective chart review collected patient demographics and medical histories from electronic medical records (EMRs). Patients were stratified by age group, with children less than 12 years old, adolescents 12-17 years old, and young adults 18 or older. HbF%, mean corpuscular volume (MCV), and absolute neutrophil count (ANC) were measured to determine HU adherence. Subgroup analyses were performed in patients with the HbSS genotype.

A total of 113 patients, approximately half female, were included in the study. The median age was 14 years old, 88% of patients had the HbSS genotype, and all patients were on HU treatment. Hu was mainly prescribed for recurring pain episodes, and 56.6% of patients had private insurance.

Young adults showed higher adherence to HU in their most recent HbF% and MCV values compared with adolescents and children. This remained true at follow-up periods of 1 and 2 years. ANC values were also significantly lower in young adults than children or adolescents over 1 year of follow-up. Chronic pain status was another factor correlated with HU adherence. Patients without chronic pain were found to have higher HbF% and MCV values than patients with chronic pain, suggesting HU adherence may have protective effects on patients with SCD. Patients without chronic pain also had lower ANC levels, further showing the correlation. A subgroup analysis of patients with HbSS led to the same correlations.

The values associated with HU adherence also correlated with fewer SCD-related emergency department visits, hospitalizations, and shorter lengths of stay. Overall, adherence to HU was also associated with less health care utilization. HU duration, patient sex, socioeconomic status, and distance from the hospital did not show significant correlations with treatment adherence.

Study limitations included a small cohort size due to it taking place at a single academic institution, which it unclear whether the findings can be generalized, and its reliance on EMR data on SCD events. The reliance on surrogate markers to gauge adherence is also not ideal. Measures such as patient self-reporting, electronic pill bottles, pill count, or medication logs could help resolve this limitation.

Overall, the findings suggest young adults adhere to HU treatment at a higher rate than children and adolescents. They also support the use of HU for its protective effects, considering patients who adhered to HU had less chronic pain and health care utilization. The authors note that several studies are exploring potential strategies to overcome challenges with HU adherence in this population.

“Optimizing adherence to HU and other disease-modifying therapies is key to improve health outcomes and HRQOL, as well as decrease risk of complications and early mortality in this vulnerable population of children, adolescents, and young adults with SCD,” the authors concluded.

Reference

Reddy PS, Cai SW, Barrera L, King K, Badawy SM. Higher hydroxyurea adherence among young adults with sickle cell disease compared to children and adolescents. Ann Med. Published online March 2, 2022. doi:10.1080/07853890.2022.2044509