5561
Of the 21 patients , there was single joint involvement in 15 ( 71 . 4 % ) patients and multiple joint involvement in six ( 28 . 6 % ) patients .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None