Chart abstraction

From each eligible chart, the following data were collected: Hb types (as defined by hemoglobin electrophoresis), gender, age, systolic and diastolic blood pressure, dates on which blood pressures were recorded, CBC, renal function tests, presence of pre-existing diagnoses of hypertension and associated medication. Specifically, the three most recent blood pressure readings taken on three separate days were recorded. The blood pressures were obtained using an automated blood pressure monitor that had been in use in GICG for 2 years including the period of the study. We collected hemoglobin and total white blood cell (WBC) counts obtained on the same days as the blood pressures, averaged them and recorded the average values in the chart. Finally, complications attributable to SCD documented in each eligible chart were recorded.

Normal blood pressure was defined as systolic blood pressure <120mmHg and diastolic blood pressure < 70 mmHg in the absence of antihypertensive medication.

Relative systemic hypertension was defined as either a systolic blood pressure (SBP) of 120 to 139 mmHg, or a diastolic blood pressure (DBP) of 70 to 89 mmHg in a subject without documented diagnosis of hypertension and not taking antihypertensive medication.

Hypertension was defined as either blood pressure of ≥140mmHg (systolic) or ≥ 90 mmHg (diastolic) in the chart or blood pressure of any value along with documented treatment with one or more antihypertensive medications.

SCD type–The current diagnostic modality for SCD at GICG is cellulose acetate electrophoresis which can distinguish between hemoglobin S and C but is limited in distinguishing between Hemoglobin S, D and G In the absence of genetic testing or confirmatory tests such as HPLC or Isoelectric focusing to provide a definitive phenotype, the SCD phenotypes “SS, SC, SS/SD, SS/SD/SG” were assigned based on cellulose acetate electrophoresis alone. The latter two phenotypes SS/SD and SS/SD/SG reflect the limitations of cellulose acetate electrophoresis in distinguishing hemoglobin S, D, and G.