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: The cumulative discontinuation rate due to GI AEs was significantly lower with etoricoxib than diclofenac ( 5 . 2 vs 8 . 5 events per 100 patient - years , respectively ; hazard ratio 0 . 62 ( 95 % CI : 0 . 47 , 0 . 81 ; p < or = 0 . 001 ) ) .
### Output Text:
The cumulative discontinuation rate due to GI AEs was significantly lower with <span class="chemical">etoricoxib</span> than <span class="chemical">diclofenac</span> ( 5 . 2 vs 8 . 5 events per 100 patient - years , respectively ; hazard ratio 0 . 62 ( 95 % CI : 0 . 47 , 0 . 81 ; p < or = 0 . 001 ) ) . 