Blood pressure thresholds for the diagnosis of hypertensive disorders of pregnancy in sickle cell disease

In this retrospective cohort study of singleton pregnancies in people with sickle cell disease (SCD) delivered at two academic centres between 1990 and 2021, we collected demographic and SCD-related data, pregnancy outcomes, and the highest systolic and diastolic blood pressure (SBP and DBP) at seven time periods. We compared the characteristics of subjects with new or worsening proteinuria (NWP) during pregnancy to those without. We then constructed receiver operating characteristic (ROC) curves to determine the blood pressure (BP) that best identifies those with NWP. The SBP or DBP thresholds which maximized sensitivity and specificity were 120 mmHg SBP (sensitivity: 55.2%, specificity: 73.5%) and 70 mmHg DBP (sensitivity: 27.6%, specificity: 67.7%). The existing BP threshold of 140/90 mmHg lacked sensitivity in both genotype groups (HbSS/HbS beta 0: SBP = 21% sensitive, DBP = 5.3% sensitive; HbSS/HbS beta+: SBP = 10% sensitive, DBP = 0% sensitive). Finally, percent change in SBP, DBP and MAP were all poor tests for identifying NWP. Existing BP thresholds used to diagnose hypertensive disorders of pregnancy (HDP) are not sensitive for pregnant people with SCD. For this population, lowering the BP threshold that defines HDP may improve identification of those who need increased observation, consideration of early delivery and eclampsia prophylaxis. People with sickle cell disease (SCD) are at an increased risk of hypertensive disorders of pregnancy (HDP). Blood pressure (BP) is low at baseline in SCD and BP thresholds to define HDP are not established for this population. Among 290 pregnancies to 197 people with SCD, diastolic BP is a 'poor' test to classify new or worsening proteinuria (NWP). Systolic BP is a poor test to classify early-onset NWP and an acceptable test for classifying late-onset proteinuria. BP thresholds lower than the standard 140/90 mmHg are needed to define HDP in SCD pregnancy.image