INTRODUCTION
Several studies have demonstrated that pre-transplant pulmonary function
metrics in patients undergoing hematopoietic stem cell transplant
(HSCT), including the diffusing capacity for carbon monoxide corrected
for hemoglobin (DLCOHgb), are associated with early
respiratory failure and lower overall survival[1-3]. A variety of algorithms have been developed
to use pulmonary function tests (PFTs) as a way to predict
post-transplant pulmonary complications [4, 5].
DLCOHgb is a large part of these algorithms. There are
two equations used to correct DLCO for hemoglobin (Hgb), the Dinakara[6] and Cotes[7] equations.
At this it is unknown if one is superior to the other in regard to
predicting morbidity and mortality in the pediatric stem cell transplant
population.
There has yet to be a study directly comparing the ability of the Cotes
and the Dinakara equations to predict morbidity and mortality following
stem cell transplant in a pediatric population. Given that previous
studies have corrected DLCO for hemoglobin inconsistently and have used
different equations, determining if using the Dinakara or Cotes
equations leads to statistically and clinically significant differences
in this population could change the way physicians counsel patients and
families prior to stem cell transplant. [4, 5, 8]
The objective of this study is to compare the Dinakara and Cotes
equations in their ability to predict post HSCT pulmonary complications
and mortality. We hypothesize that because the Cotes equation is more
widely used, the pre-transplant diffusing capacity adjusted for Hgb by
the Cotes equation in pediatric patients undergoing HSCT will predict
morbidity and mortality more accurately than the Dinakara equation
following HSCT.