Table 1. ICD-10 codes considered as URTI for the purpose of this study.

• J00 Acute nasopharyngitis [common cold]     • J01 Acute sinusitis (includes J01.0, J01.1, J01.2, J01.3, J01.4, J01.8, J01.9)     • J02 Acute pharyngitis (includes J02.0, J02.8, J02.9)     • J03 Acute tonsillitis (includes J03.0, J03.8, J03.9)     • J04 Acute laryngitis and tracheitis (includes J04.0, J04.1, J04.2)     • J05 Acute obstructive laryngitis [croup] and epiglottitis     • J06 Acute upper respiratory infections of multiple and unspecified sites (includes J06.0, J06.8, J06.9)     • J10 Influenza due to other identified influenza virus (includes J10.1)     • J11 Influenza due to unidentified influenza virus (includes J11.1)

Following codes also were considered as URTI, diseases of the middle ear categorized according to ICD-10 as:

• H65 Nonsuppurative otitis media     • H66 Suppurative and unspecified otitis media

ICD: International Classification of Disease, URTI: Upper respiratory tract infection