Sickle cell trait, hemoglobin C trait, and invasive pneumococcal disease.
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.
Poehling
Katherine A
KA
Department of aPediatrics, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA. kpoehlin@wfubmc.edu
Light
Laney S
LS
Rhodes
Melissa
M
Snively
Beverly M
BM
Halasa
Natasha B
NB
Mitchel
Ed
E
Schaffner
William
W
Craig
Allen S
AS
Griffin
Marie R
MR
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
D006444:Hemoglobin C