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abstracts & posters

Survival into Adulthood in Sickle Cell Disease from the Dallas Newborn Cohort

key information

source: Blood

year: 2014

authors: Melissa D. Mathias, Song Zhang, Zora R. Rogers, George R. Buchanan, Alecia C. Nero and Timothy L. McCavit


Background: The natural history of sickle cell disease (SCD) includes premature death. Advancements in care, such as penicillin prophylaxis, have made death during childhood uncommon. Prior survival estimates for adults with SCD have been limited by survival bias (subjects enrolled as adults) or the limitations of administrative data. No prior study has estimated survival for adults with SCD from a newborn cohort. Herein, we report an continued observation of subjects in the Dallas Newborn Cohort (DNC)1.

Methods: The DNC is an inception cohort of patients with SCD defined by: (1) diagnosis by Texas newborn screening after October 31, 1983; (2) evaluation in the pediatric sickle cell program at UT Southwestern (UTSW) / Children’s Medical Center Dallas (CMCD); and (3) confirmation of SS, SC, Sβ0 or Sβ+ genotype. Patients followed at CMCD are transitioned to adult care before the 19th birthday. To identify transitioned patients or those lost to follow-up (LTFU), we reviewed the medical records at Parkland Memorial Hospital (PMH) and UTSW University Hospital (UH), the public and private hospitals affiliated with CMCD and the most common care-sites for transitioned patients. In addition, for patients no longer actively followed at CMCD, we queried the National Death Index (NDI). The NDI is a centralized database of death records obtained from all state vital statistic bureaus in the US and is maintained by the National Center for Health Statistics. As of our query in April 2014, deaths occurring from 1/1/79 – 12/31/11 were available in the NDI. Probabilistic matching is performed by the NDI to identify subjects using identifiers such as name, social security number, birthdate, gender, state of birth, and race. Patients who were LTFU or transitioned to adult care were censored at 12/31/11 or the date of their last clinical encounter, whichever occurred latest. Patients actively followed at CMCD, PMH, or UH were censored at 12/31/13.

In addition to descriptive statistics, we constructed survival curves using the Kaplan-Meier method to evaluate overall survival and survival by genotype. Also, Cox Proportional Hazard modeling was used to assess genotype, baseline hemoglobin, baseline reticulocyte count (%), and baseline oxygen saturation as potential predictors of early mortality. To test the sensitivity of the NDI to identify deceased individuals, we submitted 36 known deaths from the cohort.

organization: Memorial Sloan-Kettering Cancer Center, New York City; University of Texas Southwestern Medical Center

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