23334
The vascular resistance index ( RI ) was significantly higher in both patient groups 0 . 58 +/- 0 . 06 for group 1 ( P < 0 . 001 ) and 0 . 64 +/- 0 . 07 for group 2 ( P < 0 . 001 ) than that in control subjects ( 0 . 48 +/- 0 . 04 ) .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None