5562
The mean age of patients with joint involvement ( 8 +/- 2 . 3 years ) were considerably lower than the patients without joint involvement ( 10 . 35 +/- 3 . 04 years ) , and this was statistically significant ( p = 0 . 008 ) .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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