Habit, a Feasibility Trial to Improve Hydroxyurea Adherence, Improves Quality of Life in Youth with Sickle Cell Disease

Background: Daily hydroxyurea (HU) adherence is often suboptimal for youth with sickle cell disease (SCD). Adolescence is a critical time to improve HU adherence as youth assume greater responsibility for medication self-management. While QOL is higher among youth prescribed HU compared to those who are not,¹little is known about how participation in an intervention to improve HU adherence is related to self- and parent-proxy reported QOL.

Methods: We conducted a 2-site randomized controlled feasibility trial with 2:1 randomization, "Hydroxyure Adherence for Personal Best in Sickle Cell Treatment: HABIT," to estimate the effect of a community health worker (CHW) intervention for youth-parent dyads, augmented by tailored text messages, on HU adherence in youth 10-18 years of age with SCD.² The secondary outcomes, reported here, were: generic QOL (PedsQL; total score and 4 subscales); disease-specific QOL (PedsQL SCD Module; total score and 9 additional subscales), and youth-parent concordance regarding self-management responsibility (Sickle Cell Family Responsibility Scale, adapted from the Diabetes Family Responsibility Questionnaire). Each outcome was measured at 0, 3 and 6 months. Descriptive statistics were used to profile each measure including a Cronbach alpha to assess scale reliability in this sample. A minimally clinically important difference (MCID) was computed for each total and subscale score as a criterion to assess clinically meaningful improvements. A linear individual growth model incorporating group assignment and time was used to examine the difference in each outcome over time. Where outcomes achieved statistical significance (p<0.05), we compared the intervention group's absolute score change from 0 to 6 months to the MCID to assess a clinically meaningful change. Data were analyzed using SAS 9.4 (Cary, NC) statistical software.

Results: Of 48 eligible dyads, 28 (youth age 14.3±2.6 years, 50% Hispanic) participated (18 intervention dyads, 10 control dyads), with 10.7% attrition. The intervention was feasible (58% enrolled), acceptable to dyads and demonstrated a trend to HU adherence improvement at 4 months.³ Cronbach alphas ranged between 0.71 and 0.97 for parent and youth measures. Incorporating group assignment and time, intervention youth reported improved generic QOL total score (p=0.04; change 9.2 [95% CI 5.7, 12.7]) and its emotional subscale (p=0.034; change 14.4 [95% CI 10.2, 18.6]), 3 disease-specific QOL subscales: worry I (p=0.009; 26.1 [95% CI 18.0, 34.2), emotions (p=0.01; change 33.0 [95% CI 23.8, 42.2]), and communication I (p=0.048; change 15.3 [95% CI 8.5, 22.1]), and a trend for improved dyad concordance regarding self-management responsibility at 3 months (p=0.07; change 1.6 [95% CI 1.0, 2.2]). In each case, score improvement exceeded its MCID. No differences were found in parent-proxy reported QOL measures.

Conclusions: HABIT improved two generic and three disease-specific youth-reported QOL outcomes in the psychosocial domain. Whether QOL improvement stemmed from greater HU adherence, CHW support and/or improved dyad self-management concordance is uncertain. These findings add to a growing body of research examining effects of interventions on QOL outcomes in youth with SCD. To confirm these findings, a multi-site HABIT randomized controlled trial powered to test intervention efficacy is planned.

References:

¹Thornburg et al. J Pediatr Hematol Oncol. 2011

²Smaldone et al. Contemp Clin Trials, 2016

³Green et al. Ped Blood & Cancer, 2017