Reduced fitness and abnormal cardiopulmonary responses to maximal exercise testing in children and young adults with sickle cell anemia.

Physiologic contributors to reduced exercise capacity in individuals with sickle cell anemia (SCA) are not well understood. The objective of this study was to characterize the cardiopulmonary response to maximal cardiopulmonary exercise testing (CPET) and determine factors associated with reduced exercise capacity among children and young adults with SCA. A cross-sectional cohort of 60 children and young adults (mean 15.1 ± 3.4 years) with hemoglobin SS or S/ß(0) thalassemia and 30 matched controls (mean 14.6 ± 3.5 years) without SCA or sickle cell trait underwent maximal CPET by a graded, symptom-limited cycle ergometry protocol with breath-by-breath, gas exchange analysis. Compared to controls without SCA, subjects with SCA demonstrated significantly lower peak VO2 (26.9 ± 6.9 vs. 37.0 ± 9.2 mL/kg/min, P < 0.001). Subjects demonstrated slower oxygen uptake (ΔVO2/ΔWR, 9 ± 2 vs. 12 ± 2 mL/min/watt, P < 0.001) and lower oxygen pulse (ΔVO2/ΔHR, 12 ± 4 vs. 20 ± 7 mL/beat, P < 0.001) as well as reduced oxygen uptake efficiency (ΔVE/ΔVO2, 42 ± 8 vs. 32 ± 5, P < 0.001) and ventilation efficiency (ΔVE/ΔVCO2, 30.3 ± 3.7 vs. 27.3 ± 2.5, P < 0.001) during CPET. Peak VO2 remained significantly lower in subjects with SCA after adjusting for age, sex, body mass index (BMI), and hemoglobin, which were independent predictors of peak VO2 for subjects with SCA. In the largest study to date using maximal CPET in SCA, we demonstrate that children and young adults with SCA have reduced exercise capacity attributable to factors independent of anemia. Complex derangements in gas exchange and oxygen uptake during maximal exercise are common in this population.

Access to patient-centered medical homes in children with sickle cell disease.

To determine the proportion of children with sickle cell disease (SCD) followed in a subspecialty clinic with access to a primary care provider (PCP) exhibiting practice-level qualities of a patient-centered medical home (PCMH). We surveyed 200 parents/guardians of children with SCD using a 44-item tool addressing PCP access, caregiver attitudes toward PCPs, barriers to healthcare utilization, perceived disease severity, and satisfaction with care received in the PCP versus SCD clinic settings. Individual PCMH criteria measured were a personal provider relationship and medical care characterized as accessible, comprehensive and coordinated. Although 94 % of respondents reported a PCP for their child, there was greater variation in the proportion of PCPs who met other individual PCMH criteria. A higher proportion of PCPs met criteria for coordinated care when compared to accessible or comprehensive care. In multivariate models, transportation availability, lower ER visit frequency and greater PCP visit frequency were associated favorably with having a PCP meeting criteria for accessible and coordinated care. Child and respondent demographics and disease severity had no impact on PCMH designation. Average respondent satisfaction scores for the SCD clinic was higher, when compared to satisfaction scores for the PCP. For children with SCD, access to a PCP is not synonymous with access to a medical home. While specific factors associated with PCMH access may be identified in children with SCD, their cause and effect relationships need further study.

The impact of thalassemia on Southeast Asian and Asian Indian families in the United States: a qualitative study.

OBJECTIVE: To describe the challenges, including sociocultural and socioeconomic barriers, faced by an urban immigrant population in the United States affected by thalassemia major. DESIGN: Ethnographic, semi-structured, 1-on-1 interviews using an interview guide developed for this study. Digital recordings were transcribed and data analyzed using constant comparative method. SETTING: University-based, Comprehensive Thalassemia Program at Children's Memorial Hospital, Chicago, IL, USA. PARTICIPANTS: Fourteen Southeast Asian and Asian Indian parents of children with transfusion dependent thalassemia. MAIN OUTCOME MEASURE: Qualitative descriptions of parental experiences, frequency of codes applied to interviews and emergent themes. RESULTS: Thalassemia has its greatest impact on the emotional and social well-being of affected children and their parents. Current and future concerns were related to disease-specific complications and challenges with management such as transfusions and chelation therapy. These perceptions were tied to parental hope for a cure, a frequently coded coping mechanism. Despite their availability, few parents relied on support systems beyond immediate family members due to perceived public knowledge gaps about thalassemia. Culturally based past experiences and barriers did not emerge as dominant themes in our analysis. CONCLUSION: The impact of thalassemia is tremendous for affected children and their parents and is due more to factors that were either disease-specific or common to other chronic disease models rather than those influenced by culture. The unmet needs of these families require additional investigation to facilitate the development of initiatives aimed at improving quality of life and lessening overall impact of thalassemia

Reproducibility of tricuspid regurgitant jet velocity measurements in children and young adults with sickle cell disease undergoing screening for pulmonary hypertension.

The reproducibility of tricuspid regurgitant jet velocity (TRJV) measurements by Doppler echocardiography has not been subjected to systematic evaluation among individuals with sickle cell disease (SCD) undergoing screening for pulmonary hypertension. We examined sources of disagreement associated with peak TRJV in children and young adults with SCD. Peak TRJV was independently measured and interpreted a week apart by separate sonographers and readers, respectively, in 30 subjects (mean age, 15.8 ± 3.3 years) who provided 120 observations. We assessed intra-/inter-reader, intra-/inter-sonographer, sonographer-reader, and within subject agreement using Intraclass Correlation Coefficient (ICC) and Cohen's kappa (κ). Agreement was examined graphically using Bland-Altman plots. Although sonographers could estimate and measure peak TRJV in all subjects, readers designated tricuspid regurgitation nonquantifiable in 10-17% of their final interpretations. Intra-reader agreement was highest (ICC = 0.93 [95% CI 0.86, 0.97], P = 0.0001) and within subject agreement lowest (ICC = 0.36 [95% CI 0.02, 0.64], P = 0.021) for single TRJV measurements. Similarly, intra-reader agreement was highest (κ = 0.74 [95% CI 0.53, 0.95], P = 0.0001) and within subject lowest (κ = 0.14 [95% CI -0.17, 0.46], P = 0.38) when sonographers and readers categorized TRJV measurements. On Bland-Altman plots, absolute differences in observations increased with higher mean TRJV readings for intra-/inter-reader agreement. Peak TRJV measurements in individual children and young adults with SCD are affected by several sources of disagreement, underscoring the need for methodological improvements that ensure reproducibility of this screening modality for making clinical decisions in this population.

Parental attitudes toward research participation in pediatric sickle cell disease.

BACKGROUND: Socio-cultural attitudes and perceptions are commonly cited barriers to the recruitment of African-Americans for medical research, yet no studies have examined the factors influencing research participation among individuals with sickle cell disease (SCD) or caregivers of children with SCD. PROCEDURE: We distributed a 32-item, self-administered survey to parents or legal guardians of children with SCD over a 6-month period. We used Pearson's chi-square to determine factors associated with a favorable attitude toward research participation and logistic regression to determine independent associations. RESULTS: We collected 151 surveys in this pilot study. In general, 86% of respondents believed more research needed to be done for SCD and 57% would allow their child to participate in a medical research study, corresponding to a favorable attitude. Respondent belief that more research needed to be done for SCD (OR 23.4, 95% CI 4.5-121.9, P = 0.001), perception of greater severity of their own child's SCD (OR 2.7, 95% CI 1.0-7.1, P = 0.041) and prior exposure to research (OR 3.2, 95% CI 1.0-10.3, P = 0.043) were significantly associated with a favorable attitude, although only the first two remained independent associations in our regression model. Attitude toward research participation was not affected by respondent country of birth. CONCLUSIONS: Parents of children with SCD who allow participation in medical research are likely to believe that more research is needed in SCD and that their child's SCD is moderate to severe. Developing effective tools, based on identified knowledge gaps related to clinical research, may improve research participation in this population.