Dr. Stewart's research interest is in clinical and outcomes research. He has received grant funding from the NIH, AHRQ, AAO-HNS Foundation, and other Foundations and industry.

He has developed and validated disease-specific instruments for use in conductive hearing loss, nasal obstruction, facial paralysis, and tonsil and adenoid disease. He has also performed outcome studies on the following diseases: hearing loss, laryngeal cancer, chronic rhinosinusitis, tonsil and adenoid disease, nasal obstruction, vertigo, head and neck reconstruction, otitis media, and pediatric obstructive sleep apnea. Dr. Stewart was the Principal Investigator for the multi-center prospective Nasal Obstruction and Septoplasty Effectiveness outcomes study, which was sponsored by the AAO-HNS Foundation.

His current active interests include development of a prospective staging system for chronic rhinosinusitis, outcome assessment after surgical management of recurrent tonsillitis, and adult obstructive sleep apnea.