In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: There was a smaller excess of MB in antiplatelet users vs nonusers with ICH ( OR , 1 . 7 ; 95 % CI , 1 . 3 - 2 . 3 ; P < 0 . 001 ) , but findings were similar for antiplatelet users with IS / TIA ( OR , 1 . 4 ; 95 % CI , 1 . 2 - 1 . 7 ; P < 0 . 001 ; P difference = 0 . 25 ) .
### Output Text:
There was a smaller excess of MB in antiplatelet users vs nonusers with ICH ( OR , 1 . 7 ; 95 % CI , 1 . 3 - 2 . 3 ; P < 0 . 001 ) , but findings were similar for antiplatelet users with IS / TIA ( OR , 1 . 4 ; 95 % CI , 1 . 2 - 1 . 7 ; P < 0 . 001 ; P difference = 0 . 25 ) . 