### Description

The risk for a child with sickle cell disease developing severe complications can be predicted based on 3 clinical parameters occurring by the age of 2 years. This can help identify children who may benefit from more intensive therapy and monitoring. The investigators were associated with the Cooperative Study of Sickle Cell Disease and represented several American medical centers.

Severe complications from sickle cell disease include:

(1) death

(2) stroke

(3) one or more episodes of acute chest syndrome

(4) two or more painful events in 1 year

Factors found before the age of 2 that were associated with severe complications:

(1) dactylitis (pain and tenderness in the hands and feet) by the age of 1

(2) anemia (with hemoglobin < 7 g/dL)

(3) leukocytosis in the absence of infection

Parameter

Finding

Relative Risk for Severe Complication

dactylitis before 1 year of age

no

1.00

yes

2.55

leukocyte count

for each 10 unit increase

1.80

hemoglobin

>= 7 g/dL

1.00

< 7 g/dL

2.47

Table 3, page 86.

The risk for severe complication based on combinations of WBC count, anemia and/or dactylitis is given in Figure 1, page 86. This data was extracted into the following table.

 Risk of Severe Complications WBC in thousands no anemia no dactylitis no anemia dactylitis anemia no dactylitis anemia dactylitis 5 0.057 0.138 0.162 0.333 7.5 0.067 0.160 0.186 0.381 10 0.079 0.186 0.215 0.426 12.5 0.095 0.22 0.254 0.477 15 0.113 0.255 0.290 0.523 17.5 0.135 0.295 0.334 0.576 20 0.156 0.333 0.373 0.619 22.5 0.183 0.378 0.421 0.670 25 0.215 0.421 0.466 0.707 27.5 0.250 0.470 0.517 0.750 30 0.285 0.52 0.568 0.790

data extrapolated from Figure 1, page 86

The following equations were used to approximate the data in JMP.

(1) no anemia and no dactylitis

risk of severe disease =

= (0.0002422 * ((WBC in thousands) ^2)) + (0.000609 * (WBC in thousands)) + 0.04865

(2) no anemia, dactylitis

risk of severe disease =

= (0.0002262 * ((WBC in thousands) ^2)) + (0.0075339 * (WBC in thousands)) + 0.0916545

(3) anemia, no dactylitis

risk of severe disease =

= (0.0002107 * ((WBC in thousands) ^2)) + (0.0090756 * (WBC in thousands)) + 0.10765

(4) anemia and dactylitis

risk of severe disease =

= (-0.000079 * ((WBC in thousands) ^2)) + (0.0212489 * (WBC in thousands)) + 0.225527