Implementation Of Transcranial Doppler Ultrasonography Screening and Primary Stroke Prevention In Urban and Rural Sickle Cell Disease Populations

Transcranial doppler (TCD) ultrasonography has been used successfully to identify children with sickle cell disease (SCD) at increased risk of stroke. A large randomized trial (STOP trial) demonstrated that initiation of chronic transfusions as primary stroke prevention in children with an abnormal TCD significantly reduced stroke risk. Based on these findings, annual TCD screening and primary stroke prevention for patients with abnormal findings are considered standard of care (SOC) for children with SCD. We report here results describing the implementation of TCD screening and primary stroke prevention in both urban and rural clinical practice.

A retrospective chart review was conducted to identify children ages 2-16 years with Hgb SS or Sß⁰ thalassemia and no history of stroke. Patients are followed in the local urban comprehensive sickle cell program at Georgia Regents University of in 4 outreach clinics in rural Georgia. Starting in 2010 TCDs conducted by a STOP trained sonographer were offered three times annually in the rural clinics. All TCD results were recorded before and after the implementation of the rural TCD program. SOC is defined as having one TCD performed annually between January 1, 2010 and December 31,2012 starting at age 2 years in patients with no history of abnormal TCD.

A total of 213 children were identified who met inclusion criteria. Table 1 describes demographic and TCD information since 2010. Prior to 2010 20% of patients had no history of TCD; following implementation of the rural TCD program 7% of patients never had a TCD (p≤ 0.01). The percentage of patients with conditional or normal TCD results since 2010 is comparable between urban and rural clinics, whereas the proportion of patients with abnormal TCDs is higher in the rural clinics (p=0.01). Overall 41% of patients achieved SOC screening. There was no difference in SOC rates between urban and rural clinics (Table 1, p=0.12). Furthermore, there was no difference in SOC rates in the urban and rural clinics in patients with a history of normal (33% and 42% respectively, p=0.21) or conditional TCDs (50% and 58% respectively, p=0.72). Among the group of patients with a history of abnormal TCDs (n=18) the majority of patients were on chronic transfusions (83%) and none have experienced a stroke. While rural patients were able to receive transfusions locally, monitoring of transfusions was difficult with 38% and 31% of rurally transfused patients lacking documentation of Hgb S% and ferritin levels respectively in the past year.

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We report here data describing implementation of the STOP trial recommendations in clinical practice with unique data on rural patients. Our data demonstrates that rural TCD screening is feasible and can achieve SOC equal to that in an urban setting. We did find a higher number of abnormal TCDs in the rural population, perhaps secondary to differences in TCD sonographer training or an unrecognized disparity in care. While the majority of children (93%) have received at least one TCD, a significant number of patients are not obtaining annual SOC screening. Chart review indicated common barriers include adherence with clinic appointments, refusal of screening, and loss to follow up care. Unlike screening, implementation of primary stroke prevention in rural patients is difficult with minimal laboratory data being followed by the hematologist. In conclusion, our data suggest that practice and physician level barriers exist that impact the ability to provide SOC primary stroke prevention. Future research should target quality measures to improve practice level barriers, provide parental education on the importance of screening and novel interventions to enhance patient adherence.