title: Sickle cell trait, hemoglobin C trait, and invasive pneumococcal disease.
abstract: BACKGROUND
  The cause of historically higher rates of invasive pneumococcal disease among blacks than whites has remained unknown. We tested the hypothesis that sickle cell trait or hemoglobin C trait is an independent risk factor for invasive pneumococcal disease.
  
  
  METHODS
  Eligible children were born in Tennessee (1996-2003), had a newborn screen, enrolled in TennCare aged <1 year, and resided in a Tennessee county with laboratory-confirmed, pneumococcal surveillance. Race/ethnicity was ascertained from birth certificates. Children were followed through 2005 until loss of enrollment, pneumococcal disease episode, fifth birthday, or death. We calculated incidence rates by race/ethnicity and hemoglobin type before and after pneumococcal conjugate vaccine (PCV7) introduction. Poisson regression analyses compared invasive pneumococcal disease rates among blacks with sickle cell trait or hemoglobin C trait with whites and blacks with normal hemoglobin, controlling for age, gender, time (pre-PCV7, transition year, or post-PCV7) and high-risk conditions (eg, heart disease).
  
  
  RESULTS
  Over 10 years, 415 invasive pneumococcal disease episodes occurred during 451,594 observed child-years. Before PCV7 introduction, disease rates/100,000 child-years were 2941 for blacks with sickle cell disease, 258 for blacks with sickle cell trait or hemoglobin C trait and 188, 172, and 125 for blacks, whites, and Hispanics with normal hemoglobin. Post-PCV7, rates declined for all groups. Blacks with sickle cell trait or hemoglobin C trait had 77% (95% CI = 22-155) and 42% (95% CI = 1-100) higher rates than whites and blacks with normal hemoglobin.
  
  
  CONCLUSIONS
  Black children with sickle cell trait or hemoglobin C trait have an increased risk of invasive pneumococcal disease.
authors.affiliation: Department of aPediatrics, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA. kpoehlin@wfubmc.edu
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Poehling
authors.forename: Laney S
authors.initials: LS
authors.lastname: Light
authors.forename: Melissa
authors.initials: M
authors.lastname: Rhodes
authors.forename: Beverly M
authors.initials: BM
authors.lastname: Snively
authors.forename: Natasha B
authors.initials: NB
authors.lastname: Halasa
authors.forename: Ed
authors.initials: E
authors.lastname: Mitchel
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Allen S
authors.initials: AS
authors.lastname: Craig
authors.forename: Marie R
authors.initials: MR
authors.lastname: Griffin
mesh_terms: D002675:Child, Preschool; D005260:Female; D006444:Hemoglobin C / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000209:etiology; D011159:Population Surveillance; D012307:Risk Factors; D012805:Sickle Cell Trait / Q000150:complications*; D013296:Streptococcus pneumoniae / Q000302:isolation & purification; D013714:Tennessee / Q000453:epidemiology
chemical_list: D006444:Hemoglobin C