2491
Age was categorized into four groups : 20 - 44 , 45 - 64 , 65 - 74 , and 75 + . RESULTS : At the initiation of dialysis PD patients were approximately 6 years younger ( P < 0 . 0001 ) than HD patients .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 None