3.2 Patient characteristics
All selected studies formed a patient pool of 1404 patients with 374 underwent TVD and 1030 underwent non-TVD procedures.
Based on existing data, mean age was 12.96 months and 8.15 months (p=0.1752), mean weight was 6.62 kg and 6.74 kg (p=0.8362) respectively for TVD and non-TVD group. Weighted mean follow-up time was 39.89±24.24 months in TVD group and 43.36±27.15 months in non-TVD group.