Table 3

Baseline prognostic factors for abnormal TCD, abnormal MRA, silent strokes, and cerebral vasculopathy risk (strokes, abnormal TCD, abnormal MRA, or silent strokes) by the age of 14 years in SCA participants

Baseline parameters
Abnormal TCD
Abnormal MRA
Silent strokes
Stroke or abnormal TCD or abnormal MRA or silent stroke
No. events/
HR (95% CI)PNo. events/
HR (95% CI)PNo. events/
HR (95% CI)PNo. events/
HR (95% CI)
P
No. patientsNo. patientsNo. patientsNo. patients
Univariate analysis             
    Sex             
        Male 25/115 = 22% 1.1 (0.6-1.9) .86 10/71 = 14% 0.7 (0.3-1.6) .4 21/67 = 31% 1.6 (0.8-3.4) .065 40/71 = 56% 1.3 (0.8-2.2) .253 
        Female 20/102 = 20% 1  12/61 = 20%   11/59 = 19%   26/61 = 43%   
    G6PD             
        Normal 31/161 = 19% 1  11/100 = 11%   24/97 = 25%   49/100 = 49%   
        Deficiency 10/21 = 48% 2.0 (1.0-4.0)* .042* 8/16 = 50% 4.8 (1.9-11.9)* .001* 7/13 = 54% 2.0 (0.9-4.3) .072 13/16 = 81% 1.8 (0.9-3.3) .082 
    α-Thalassemia             
        Present 09/82 = 11% 1  2/51 = 3.9%   13/50 = 26%   20/51 = 39%   
        Absent 30/105 = 29% 2.8 (1.3-5.8)* .007* 16/74 = 22% 3.7 (1.1-12.7)* .038* 18/69 = 26% 1.1 (0.5-2.1) .936 43/74 = 58% 1.6 (0.9-2.6) .116 
    Leukocyte count per 1 × 109/L increase  1.1 (1.0-1.1)* .001*  1.1 (1.0-1.2)* .003*  1.0 (0.9-1.1) .707  1.0 (0.9-1.1) .061 
    Neutrophil count per 1 × 109/L increase  1.0 (0.9-1.1) .546  1.0 (0.9-1.2) .725  0.9 (0.8-1.1) .336  1.0 (0.9-1.1) .64 
    Platelet count per 1 × 109/L increase  1.0 (1.0-1.0) .235  0.9 (0.6-1.4) .643  1.0 (1.0-1.0) .477  1.0 (1.0-1.0) .38 
    Hemoglobin level per 1 g/dL increase  0.73(0.54-0.97)* .034*  0.47 (0.28-0.79)* .004*  0.67 (0.46-0.98)* .048*  0.77 (0.60-1.00)* .050* 
    MCV per (fL) increase  1.04 (0.99-1.08) .053  1.05 (0.98-1.12) .149  1.02 (0.98-1.07) .292  1.03 (0.99-1.07) .069 
    Reticulocyte count per 1 × 109/L increase  1.005 (1.002-1.008) .001*  1.005 (1.000-1.010) .069  1.0 (1.0-1.0) .641  1.003 (1.000-1.005)* .028* 
    HbF per 1% increase  1.02 (0.98-1.06) .279  0.98 (0.91-1.06) .688  0.97 (0.92-1.03) .265  1.0 (1.0-1.0) .94 
    LDH per IU/mL increase  2.73 (1.14-5.64)* .024*  7.31 (1.91-27.92)* .004*  2.06 (0.72-5.88) .177  3.31 (1.61-6.83)* .001* 
Multivariate analysis             
    G6PD deficiency  2.3 (1.0-5.2)* .046*  3.6 (1.2-11.0)* .024*       
    Absence of α-thalassemia  2.5 (1.04-5.0)* .041*          
    Hemoglobin level per 1 g/dL decrease        1.7 (1.1-2.8)* .011*    
    Reticulocyte count per 1 × 109/L increase  1.005* (1.002-1.008)* <.001*        1.003 (1.000-1.006)* .04* 
    LDH per IU/mL increase     4.9 (1.2-19.7)* .027*     2.78 (1.33-5.81)* .007* 
Baseline parameters
Abnormal TCD
Abnormal MRA
Silent strokes
Stroke or abnormal TCD or abnormal MRA or silent stroke
No. events/
HR (95% CI)PNo. events/
HR (95% CI)PNo. events/
HR (95% CI)PNo. events/
HR (95% CI)
P
No. patientsNo. patientsNo. patientsNo. patients
Univariate analysis             
    Sex             
        Male 25/115 = 22% 1.1 (0.6-1.9) .86 10/71 = 14% 0.7 (0.3-1.6) .4 21/67 = 31% 1.6 (0.8-3.4) .065 40/71 = 56% 1.3 (0.8-2.2) .253 
        Female 20/102 = 20% 1  12/61 = 20%   11/59 = 19%   26/61 = 43%   
    G6PD             
        Normal 31/161 = 19% 1  11/100 = 11%   24/97 = 25%   49/100 = 49%   
        Deficiency 10/21 = 48% 2.0 (1.0-4.0)* .042* 8/16 = 50% 4.8 (1.9-11.9)* .001* 7/13 = 54% 2.0 (0.9-4.3) .072 13/16 = 81% 1.8 (0.9-3.3) .082 
    α-Thalassemia             
        Present 09/82 = 11% 1  2/51 = 3.9%   13/50 = 26%   20/51 = 39%   
        Absent 30/105 = 29% 2.8 (1.3-5.8)* .007* 16/74 = 22% 3.7 (1.1-12.7)* .038* 18/69 = 26% 1.1 (0.5-2.1) .936 43/74 = 58% 1.6 (0.9-2.6) .116 
    Leukocyte count per 1 × 109/L increase  1.1 (1.0-1.1)* .001*  1.1 (1.0-1.2)* .003*  1.0 (0.9-1.1) .707  1.0 (0.9-1.1) .061 
    Neutrophil count per 1 × 109/L increase  1.0 (0.9-1.1) .546  1.0 (0.9-1.2) .725  0.9 (0.8-1.1) .336  1.0 (0.9-1.1) .64 
    Platelet count per 1 × 109/L increase  1.0 (1.0-1.0) .235  0.9 (0.6-1.4) .643  1.0 (1.0-1.0) .477  1.0 (1.0-1.0) .38 
    Hemoglobin level per 1 g/dL increase  0.73(0.54-0.97)* .034*  0.47 (0.28-0.79)* .004*  0.67 (0.46-0.98)* .048*  0.77 (0.60-1.00)* .050* 
    MCV per (fL) increase  1.04 (0.99-1.08) .053  1.05 (0.98-1.12) .149  1.02 (0.98-1.07) .292  1.03 (0.99-1.07) .069 
    Reticulocyte count per 1 × 109/L increase  1.005 (1.002-1.008) .001*  1.005 (1.000-1.010) .069  1.0 (1.0-1.0) .641  1.003 (1.000-1.005)* .028* 
    HbF per 1% increase  1.02 (0.98-1.06) .279  0.98 (0.91-1.06) .688  0.97 (0.92-1.03) .265  1.0 (1.0-1.0) .94 
    LDH per IU/mL increase  2.73 (1.14-5.64)* .024*  7.31 (1.91-27.92)* .004*  2.06 (0.72-5.88) .177  3.31 (1.61-6.83)* .001* 
Multivariate analysis             
    G6PD deficiency  2.3 (1.0-5.2)* .046*  3.6 (1.2-11.0)* .024*       
    Absence of α-thalassemia  2.5 (1.04-5.0)* .041*          
    Hemoglobin level per 1 g/dL decrease        1.7 (1.1-2.8)* .011*    
    Reticulocyte count per 1 × 109/L increase  1.005* (1.002-1.008)* <.001*        1.003 (1.000-1.006)* .04* 
    LDH per IU/mL increase     4.9 (1.2-19.7)* .027*     2.78 (1.33-5.81)* .007* 

Shown are the results of the Cox regression univariate and multivariate analysis performed in to assess baseline predictive factors associated with abnormal TCD, abnormal MRA (stenosis), silent stroke, and those associated with the cumulative cerebral risk.

For this analysis, biologic parameters were (as in the Table 1) the average of those obtained at baseline after the age of 12 months and before the age of 3 years, a minimum of 3 months away from a transfusion, 1 month from a painful episode, and before any intensive therapy (hydroxyurea, transfusion program or stem cell transplantation).

CI indicates confidence interval; HbF, fetal hemoglobin; HR, hazard ratio; LDH, lactate dehydrogenase; MCV, mean corpuscular volume; MRA, magnetic resonance angiography; and SCA, sickle cell anemia.

*

Statistically significant.

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