February 8, 2013Open Access
View Full PaperTen-Year Incidence of Chagas Cardiomyopathy Among Asymptomatic Trypanosoma cruzi –Seropositive Former Blood Donors
Key Result
Asymptomatic Trypanosoma cruzi-seropositive blood donors developed Chagas cardiomyopathy at a rate of 24% over ~11 years compared to 5% in seronegative controls.
Study Design
Type
Cohort (n=987)
Blinding
Blinded outcome assessment
Multicenter
Yes
Structured PICO
Does Trypanosoma cruzi seropositivity increase the incidence of Chagas cardiomyopathy in initially asymptomatic blood donors?
P
Population
987 initially healthy blood donors (499 T cruzi-seropositive and 488 matched seronegative) followed for approximately 11 years to assess the incidence of Chagas cardiomyopathy.
E
Exposure
Trypanosoma cruzi seropositivity (exposure)
C
Comparator
Trypanosoma cruzi seronegativity
O
Outcome
Incidence of Chagas cardiomyopathy, adjudicated by a blinded panel of 3 cardiologists based on ECG and echocardiogram resultshard clinical
Asymptomatic T. cruzi-seropositive blood donors have a substantial 10-year incidence of developing Chagas cardiomyopathy, although the disease is typically mild at diagnosis.
Main Result
Effect estimate: Incidence difference 1.85 per 100 person-years
Absolute Event Rate: 24% vs 5%
Abstract
BACKGROUND: Very few studies have measured disease penetrance and prognostic factors of Chagas cardiomyopathy among asymptomatic Trypanosoma cruzi-infected persons. METHODS AND RESULTS: We performed a retrospective cohort study among initially healthy blood donors with an index T cruzi-seropositive donation and age-, sex-, and period-matched seronegatives in 1996 to 2002 in the Brazilian cities of São Paulo and Montes Claros. In 2008 to 2010, all subjects underwent medical history, physical examination, ECGs, and echocardiograms. ECG and echocardiogram results were classified by blinded core laboratories, and records with abnormal results were reviewed by a blinded panel of 3 cardiologists who adjudicated the outcome of Chagas cardiomyopathy. Associations with Chagas cardiomyopathy were tested with multivariate logistic regression. Mean follow-up time between index donation and outcome assessment was 10.5 years for the seropositives and 11.1 years for the seronegatives. Among 499 T cruzi seropositives, 120 (24%) had definite Chagas cardiomyopathy, and among 488 T cruzi seronegatives, 24 (5%) had cardiomyopathy, for an incidence difference of 1.85 per 100 person-years attributable to T cruzi infection. Of the 120 seropositives classified as having Chagas cardiomyopathy, only 31 (26%) presented with ejection fraction <50%, and only 11 (9%) were classified as New York Heart Association class II or higher. Chagas cardiomyopathy was associated (P<0.01) with male sex, a history of abnormal ECG, and the presence of an S3 heart sound. CONCLUSIONS: There is a substantial annual incidence of Chagas cardiomyopathy among initially asymptomatic T cruzi-seropositive blood donors, although disease was mild at diagnosis.