1737
This difference was also significant in the primary valve surgery and the high risk surgery subgroups ( 7 . 9 % vs 1 . 2 % , P = 0 . 003 ; 7 . 3 % vs 2 . 4 % , P = 0 . 035 , respectively ) .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 None