Dessap et al developed a nomogram for predicting the risk of a delayed hemolytic transfusion reaction for a patient with sickle cell disease. Providing compatible blood can be a challenge for a patient with sickle cell disease who requires frequent transfusions. The authors are from multiple institutions in France.
Patient selection: sickle cell disease after blood transfusion
Outcome: changes of a delayed hemolytic transfusion reaction (DHTR)
Parameters:
(1) hemoglobin in g/dL in sample taken soon after transfusion
(2) percent hemoglobin A in sample taken soon after transfusion
(3) hemoglobin in g/dL in sample taken when DHTR suspected
(4) percent hemoglobin A in sample taken when DHTR suspected
(5) number of days between samples
concentration of hemoglobin A in first specimen after transfusion =
= (percent of hemoglobin A) / 100 * (hemoglobin in sample)
concentration of hemoglobin A in second specimen =
= (percent of hemoglobin A) / 100 * (hemoglobin in sample)
relative change in hemoglobin A in percent =
= ((hemoglobin A in second specimen) - (hemoglobin A in first specimen)) / (hemoglobin A in first specimen) * 100
The authors created a nomogram (Figure 3) with 2 lines that divide a gridded square into 3 zones:
(1) low likelihood DHTR
(2) intermediate likelihood DHTR
(3) high likelihood DHTR
The delimiters for the square were:
(1) days > 0 and <= 60
(2) relative change in hemoglobin A from 20 to -100 percent
The line separating low from intermediate zones:
relative change in hemoglobin A concentration in percent =
= (-1.936957 * (number of days)) - 10.9
The line separating intermediate from high zones =
relative change in hemoglobin A concentration in percent =
= (-2.036667 * (number of days)) - 38.9
