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: Before the switch , 11 . 5 % of patients had high - grade proteinuria ( > 1 . 0 g / day ) ; this increased to 22 . 9 % postswitch ( p = 0 . 006 ) .
### Output Text:
Before the switch , 11 . 5 % of patients had high - grade proteinuria ( > 1 . 0 g / day ) ; this increased to 22 . 9 % postswitch ( p = 0 . 006 ) . 