Frequency (Incidence) of Smell Loss (Hyposmia) and Associated Anorexia in the United States

Abstract

Hyposmia is generally considered a rare occurrence among patients in the U.S. It is also considered a minor loss of sensory function compared to loss of vision or hearing. However, it occurs much more frequently than is usually considered. It is commonly accompanied by loss of flavor from food with subsequent loss of appetite and anorexia. Hyposmia may affect as many as 21 million people in the U.S. A common cause of hyposmia occurs following an influenza‐like illness and accounts for 300,000 patients annually. Significant head injury occurs yearly in over 1.6 million people in the U.S. with over 900,000 patients suffering acute or chronic hyposmia. Allergic rhinitis occurs in about 25 million patients in the U.S. with over 1 million patients suffering acute or chronic hyposmia. Adverse reactions to therapeutic drugs including antihypertensives, hypoglycemic agents, antidepressants, antibiotics, chemotherapeutic agents and other therapeutic drugs affects over 120 million patients in the U.S. with over 20 million patients experiencing transient or permanent smell loss. Of the 880 million clinic visits to physicians in the U.S. in 2006 if only 1/1000 were related to an acute or chronic episode of hyposmia then 880,000 patients would experience smell loss on a yearly basis. Other patient groups which commonly experience hyposmia are those with neurodegenerative diseases (multiple sclerosis, Parkinson's disease and Alzheimer's disease), those in nursing homes or chronic care facilities, patients with cancer receiving x‐irradiation, those with zinc malabsorption and other metabolic disorders including diabetes and thyroid disease. These estimates indicate that hyposmia is a common occurrence in the U.S. although it is not currently recognized as such.