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: In this prevention study , SBP in the atorva + dex group was increased from 115 + / - 0 . 4 to 124 + / - 1 . 5 mmHg , but this was significantly lower than in the dex - only group ( P ' < 0 . 05 ) .
### Output Text:
In this prevention study , SBP in the <span class="chemical">atorva</span> + <span class="chemical">dex</span> group was increased from 115 + / - 0 . 4 to 124 + / - 1 . 5 mmHg , but this was significantly lower than in the <span class="chemical">dex</span> - only group ( P ' < 0 . 05 ) . 