Implementation of Transcranial Doppler Ultrasound Stroke Risk Screening in Urban and Rural Sickle Cell Disease Clinics in Zambia

Introduction Transcranial Doppler Ultrasound (TCD) has a long-established role in the diagnosis of sickle cell disease (SCD) related vasculopathy, paving the way for therapeutic interventions that reduce stroke risk by 92% in high-risk children. In sub-Saharan Africa (SSA), where 75% of the global burden of SCD resides and an estimated 1.03 million children are afflicted, SCD-associated stroke risk evaluation with TCD remains an urgent unmet need.

Methods Through a collaborative network with Nationwide Children's Hospital in the USA, 6 health facilities including two in Zambia, had personnel and infrastructure set up to introduce Transcranial Doppler Ultrasonography clinical and research centres of excellence (TCD-COE). The SSA TCD Academy course, designed to advance the technical expertise and capability of participants to perform TCD was created. Learners completed virtually delivered didactic lectures focused on neuroanatomy, scan techniques, doppler waveform characteristics, diagnostic criteria, and clinical application in children. Thereafter, they underwent a week-long, hands-on, practical, introduction to TCD, to increase understanding of the key concepts and to develop basic TCD scanning proficiency. An electronic registry, collecting demographic, clinical and laboratory data was also set up. Ongoing mentorship occurred through real-time consultation and evaluation with feedback given directly from a TCD expert to trainees as they performed the screening. Following completion of the course, participants trained began TCD screening in existing sickle cell out-patient clinics at their institutions, namely, the University Teaching Hospitals-Children's Hospital in Lusaka, and at Chipata Central Hospital in Chipata, in Zambia.

Results Trainees selected included a pediatric neurologist, a pediatrician in training, 2 nurses and 2 radiographers. They completed the TCD academy course content over 6 months’ time. To date, over a period of an additional six months, 171 children in Lusaka and 71 children in Chipata with SCD have undergone their first ever, successful TCD stroke risk screening, using a standardized protocol focused on terminal internal carotid artery and middle cerebral artery evaluation. Plans to incorporate TCD screening into routine clinical care are underway. This will require rolling out the screening from the current outpatient clinic day to additional days, to the in-lay ward, as well as to train more staff.

Several factors may have facilitated the successful implementation of TCD services into the SCD clinics. The participating institutions had already established SCD clinics, with dedicated staff, therapeutic interventions, and monitoring facilities in place. A referral system was in place to allow the trained staff to interact with the physicians in charge of each SCD clinic. Additionally, the trainees had prior experience with other kinds of ultrasound performance, allowing for more rapid acquisition of the technical skill. Lastly, TCD screening for stroke risk was considered standard of care, according to the Zambian guidelines, catalyzing a notable pre-existing high awareness among the staff and affected families and a high acceptance of the service.

Several challenges were also encountered. The physical space available is relatively limited, with insufficient room to set up TCD equipment and examination tables for children to rest comfortably during examinations. Additional space was provided, and the teams were able to expand to locations adjacent to clinics to overcome this obstacle. Staff often had multiples tasks, oftentimes only a single provider could be present to perform TCD examinations. Providing dedicated time and staff may offset this setback. Additionally, other days when staff were available, screening was limited based on the availability of the single machine. This obstacle was overcome with the provision of an additional TCD unit. Lastly, some families did not have financial means to return for the recommended follow up visits.

Conclusions TCD screening, to determine stroke risk in children with SCD in SSA is feasible with a modest degree of investment in equipment, staff, and training.

No relevant conflicts of interest to declare.