Demographic characteristics of subjects and controls
The mean age of respondents in Genotype SS group was 9.73±4.09 while for controls, it was 8.88±4.00 (t=1.05, p=0.3). The mean age was 9.75±3.98 years for males and 9.83±4.60 for females (t= -0.62, p= 0.95) in the subjects. Among the controls the mean ages for males and females were 8.81±3.91 and 8.96±4.18 years respectively (t= -0.13, p=0.89). The Male: Female ratio was 1:1 (Table 1).
Mean TAPSE, right ventricular pressure and tricuspid in flow velocities of subjects and controls
The mean TAPSE in subjects, 28.24±5.23 (Zscore: 0.258±1.10) was higher than that in control, 25.82±3.59 (Zscore: - 0.263±0.80), and the difference in mean was statistically significant, (t=2.703, p=0.008). The mean right ventricular pressure (RVP, an index of Pulmonary pressure) in subjects, 21.61±9.49 (Zscore: 0.49±1.2) was higher than that in control, 13.89±2.10 (Zscore: -0.49±0.3) and the difference in mean was statistically significant, (Student t=5.613, <0.001).
The mean tricuspid inflow velocities (TVE/A) of subjects, 1.88±1.43 (Zscore: 1.87±1.4) was higher than that in control, 1.70±0.21 (1.69±0.2) but the difference in mean was not found to be statistically significant, (Student t=0.904, p=0.34), Table 2.
Prevalence of right ventricular dysfunction using TAPSE
Significantly higher proportion of respondents in subjects had abnormal TAPSE, 25 (50.0% when compared with those in control, 11 (22.0%), (χ2=8.5, p=0.0035). Among the subjects, 25 (50%) had values within the normal range, 3 (6%) had values above +2SD and 7 (14%) had values above +1SD, 28% had values -1SD and 2%, -2SD below the mean (Table 3).
Correlation between TAPSE, TVE/A and TRV in subjects and controls
There was a positive correlation between TAPSE and TVE/A, increases in TVE/A were correlated with increases in TAPSE but this was not found to be statistically significant in both groups, (n=50, r=0.14, p=0.33) and (n=50, r=0.17, p=0.23) respectively. There was a significant positive correlation between TAPSE versus TRV in subjects (n=50, r=0.34, p=0.02). In controls, the correlation was positive although not statistically significant (n=50, t= 0.12, p= 0.91).
Prevalence of pulmonary hypertension
A significantly higher proportion of subjects (25.5%) had Pulmonary hypertension (RVP) when compared with control (2.0%) and the difference in proportions was found to be statistically significant, (χ2=11.668, p=0.001). The prevalence of right ventricular diastolic dysfunction in subjects was 9.8 % while control was 0%.
Indices of RV function in subjects based on gender
With respect to gender, 14.3% of male subjects had pulmonary hypertension (RVP), compared to 4.3% females (χ2=1.410, p=0.235).
For subjects, the mean TAPSE for males was 28.12±5.84 (Zscore: TPSE; 0.23±1.26) and this was lower than that for females, 28.37±4.51 (Zscore: 0.29±0.97) but the difference in mean was not found to be statistically significant, (t= -0.170, p=0.866). The mean TVR for males, 17.87±8.32 (Zscore: -0.21±0.92) was higher than that for females, 16.79±2.98 (Zscore: -0.27±0.74) but the difference in mean was found not to be statistically significant, (t=0.27, p=0.79). The mean TVE/A for males, 2.06±1.93 (Zscore: 0.26±1.89) was higher than that for females, 1.67±0.22 (Zscore: -0.11±0.22) but the difference in mean was found not to be statistically significant, (t=0.94, p=0.35). Table 4.
Indices of RV function in controls based on gender
For Control, the mean TAPSE for males, 25.99±3.71 (Zscore: -0.23±0.80) was higher than that of females, 25.64±3.52 (Zscore: -0.30±0.76) but the difference in mean was not found to be statistically significant, (t=0.34, p=0.74). The mean TVR for males, 14.54±1.83 (Zscore: 0.29±1.11) was comparable to that of females, 13.77±1.25 (Zscore: 0.18±1.10), (t=0.38, p=0.71). The mean TVE/A for males, 1.66±0.25 (Zscore: -0.12±0.24) was lower than that of females, 1.73±0.16 (-0.05±0.16) but the difference in mean was not found to be statistically significant, (t = -1.11, p=0.26). Table 5
Correlation of age with Indices of RV function of TAPSE and TVE/A in Subjects and controls
There was a strong positive correlation between age in years and TAPSE in both subjects and controls, increases in age were correlated with increases in TAPSE and this was found to be statistically significant (n=50, r=0.52, p<0.001) and (n=50, r= 0.62, p<0.001) respectively. There was no correlation between age in years and TVE/A in subjects and controls (n=50, r=0.05, p= 0.75) and (n=50, r= 0.06, p=0.66) respectively.