Cohort Tracking of Sickle Cell Trait-Positive Births Identified by Newborn Screening, California, 1991-2013: Public Health Surveillance for Sickle Cell Trait.

Objectives: Sickle cell trait (SCT) is the carrier status for sickle cell disease, and people with SCT have both hemoglobin A (HbA) and sickling hemoglobin (HbS). SCT is generally regarded as a benign condition, but clinical complications can be substantial. No registry or surveillance system exists to track health outcomes for people with SCT; this study aimed to identify methodology for surveillance.

Methods: This longitudinal analysis included all live births with SCT identified by the California Department of Public Health Newborn Screening (NBS) Program from 1991 through 2013 and 3 matched controls per newborn, linked to death data in California for 1991-2013.

Results: There were 94 240 live births with SCT and 282 720 matched healthy controls; 693 (0.74%) deaths occurred in the SCT group, and 1910 (0.68%) deaths occurred among the matched controls. Those with SCT had an increased mortality hazard ratio (MHR) compared with matched controls (11% higher; P = .02). When stratified, the MHR was higher among those aged 1 to 4 years (44% higher; P < .001) and 5 to 14 years (48% higher; P = .005) than among the matched controls. Examination of causes of death showed only a slightly higher-than-expected risk of death due to respiratory causes among people with SCT.

Conclusions: These findings highlight the need for population-level research, including investigation into causes of death, to inform clinical management and counseling for SCT. Other states may replicate this methodology with population-based data sources. Further surveillance of the health of those with SCT is needed.