Patterns of seasonal and pandemic influenza-associated health care and mortality in Ontario, Canada

BMC Public Health

Table 1 ICD-9respiratorydiseasecodes for diagnoses included in the present study

Code	Definition
460–466	Acute respiratory infections (ARI)
460	Acute nasopharyngitis (common cold)
461	Acute sinusitis
462	Pharyngitis, acute
463	Tonsillitis, acute
464	Acute laryngitis and tracheitis
465	Acute upper respiratory infections of multiple or unspecified sites
466	Acute bronchitis and bronchiolitis
480–488	Pneumonia and influenza (P&I)
480	Viral pneumonia
486	Pneumonia, organism unspecified
487	Influenza
488	Influenza due to identified Avian influenza virus
488.1	Influenza due to identified 2009 H1N1 virus

Codes 481–485 were excluded because they indicate types of pneumonia not associated with influenza. Subcodes are not listed, except 488.1, which is highlighted because pandemic H1N1 is not normally considered a subset of “Avian influenza” and would not be expected to be found in this category

ISSN: 1471-2458