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: However , the risk of reaction to these alternative study drugs is statistically increased by a history of chronic urticaria and , above all , by a history of NSAID - induced angioedema .
### Output Text:
However , the risk of reaction to these alternative study drugs is statistically increased by a history of chronic urticaria and , above all , by a history of <span class="chemical">NSAID</span> - induced angioedema . 