Pain Experiences in Children with Sickle Cell Disease in the Era of Hydroxyurea

Background:  Pain is the most common complication of sickle cell disease (SCD), and pain diaries are an effective way to capture pain experienced by both children and adults for many conditions, including SCD. The most recent data on pain experienced by children with SCD outside the clinical trial setting, particularly those with Hemoglobin (Hb) SS disease, were collected prior to the publication of the Baby-HUG trial in 2011, which found hydroxyurea to be safe for use in early childhood. One study found that school-aged children with SCD had at least one pain episode per month; another longitudinal study reported that SCD-related pain was experienced by children on 8% of pain diary days. In the era of hydroxyurea use in children, the occurrence of SCD-related pain episodes in children has not been well studied, especially among those with Hb SS disease.

Methods:  Parent/child dyads were recruited for a 6-month pilot study of the use of home pain plans and pain diaries from a pediatric hematology clinic based in a safety net institution. The study ran from February to November 2014. Dyads were eligible if the child with SCD was aged 5-15 years and had at least one episode of pain in the year prior to enrollment, by parent report. Parents and children were asked to fill out the diary each day. They received weekly phone calls for the first month, then monthly phone calls until the close of the study, to remind them to complete the daily pain diary and mail it back monthly; $20 gift cards were given for each diary returned. We excluded data from dyads that recorded less than 4 weeks of pain diary data.

Results:  Thirty-six parent/child dyads were approached and 30 (83%) consented to enroll in the study. Twenty-six (87%) dyads recorded at least four weeks of data. The average age of the child with SCD was 10.3 ± 3.0 years and 20 (77%) were insured through Medicaid. Twenty-two (85%) children had Hb SS disease, of whom 21 were prescribed hydroxyurea. Data were recorded per dyad on average 135 ± 46 diary days. One child with Hb SS disease reported no pain during the study period. The remaining 25 children had any pain and SCD-related pain an average of 8% and 4% diary days, respectively. Nearly all children reporting non-SCD-related pain had headache or abdominal pain. Ten (38%) children missed at least one day of school during the study period.

Conclusions:  In this sample of children with SCD, composed predominantly of those with Hb SS disease prescribed hydroxyurea, pain was an infrequent occurrence and was attributed to SCD only half the time. This study suggests that SCD-related pain experienced by children may be lower than previously reported. Further study is warranted, especially among those prescribed hydroxyurea.