Influenza and seasonal patterns of hospital use by older adults in long-term care and community settings in Ontario, Canada

Objectives. We compared seasonal influenza hospital use among older adults in long-term care (LTC) and community settings. Methods. We used provincial administrative data from Ontario to identify all emergency department (ED) visits and hospital admissions for pneumonia and influenza among adults older than 65 years between 2002 and 2008. We used sentinel laboratory reports to define influenza and summer seasons and estimated mean annual event rates and influenza-associated rates. Results. Mean annual pneumonia and influenza ED visit rates were higher in LTC than the community (rate ratio [RR] for influenza season = 3.9; 95% confidence interval [CI] = 3.8, 4.0; for summer = 4.9; 95% CI = 4.8, 5.1) but this was attenuated in influenza-associated rates (RR = 2.4; 95% CI = 2.1, 2.8). The proportion of pneumonia and influenza ED visits attributable to seasonal influenza was 17% (15%-20%) in LTC and 28% (27%-29%) in the community. Results for hospital admissions were comparable. Conclusions. We found high rates of hospital use from LTC but evidence of lower impact of circulating influenza in the community. This differential impact of circulating influenza between the 2 environments may result from different influenza control policies.