Nationwide trends in pneumonia hospitalization rates and mortality, Denmark 1997-2011

OBJECTIVE: To provide up-to-date population-based data on nationwide trends in pneumonia hospitalization rates and associated 30-day mortality.

METHODS: Using medical databases we identified all in-hospital episodes of pneumonia between 1997 and 2011. We computed age- and sex-standardized hospitalization rates of total and first-time pneumonia-related hospitalization and adjusted 30-day mortality rates by calendar year.

RESULTS: Among 552,528 pneumonia-related hospitalizations in Denmark between 1997 and 2011, 385,985 (69.9%) were first-time events. Total pneumonia hospitalizations increased by 63%, from 4.96 per 1000 population in 1997 to 8.09 in 2011. Rates of first-time pneumonia per 1000 population increased by 33%, from 3.99 in 1997 to 5.31 in 2011. Pneumonia rates stabilized in the mid-00s but primary pneumonia rates increased 16% from 2008 to 2011, most notably among children and young adults. In patients aged ≥80 years the rate of hospitalizations with secondary pneumonia more than doubled during the study period. Average 30-day mortality remained stable at 13%, but increased slightly over time in patients aged ≥80 years.

CONCLUSIONS: In an era of smoking cessation and vaccination efforts, pneumonia hospitalization rates are continuously increasing, largely driven by secondary diagnoses and recurrent pneumonia episodes in elderly patients. Thirty-day mortality remains persistently high.