This study was conducted as part of the Thalassemia Clinical
Research Network’s Thalassemia Longitudinal Cohort study.
The Thalassemia Clinical Research Network is a National
Heart, Lung, and Blood Institute–funded research network
composed of six core centers in the United States, Canada, and
the United Kingdom and their 10 associated satellite centers.
Patients with thalassemia who were regularly cared for at one
of these centers were invited to participate in the longitudinal
cohort study between May 2007 and December 2009. The
overall goal of the longitudinal cohort study was to describe
the prevalence and incidence of complications related to
thalassemia. The study is a prospective, longitudinal, cohort
study with baseline and annual collection of routine clinical
care data through chart review, patient questionnaires, and
detailed genotyping characterization. Patient inclusion criteria
were diagnosis of thalassemia regardless of genotype but,
in general, more severe phenotypes who required a minimum
of annual monitoring of comorbidities at their local clinic,
both sexes, and all ages. Exclusion criteria included subjects
with thalassemia trait, those with
-thalassemias and hemoglobin
9 g/dL with no history of major complications, those
whohad received a bone marrow transplant, or those subjects
unwilling to be followed on an annual basis. The protocol was
approved by the Thalassemia Clinical Research Network Data
and Safety Monitoring Board and by the ethical review boards
of all participating Thalassemia Clinical Research Network institutions.
Informed written consent, and assent in the case of
a minor, was obtained from all participants.