Having had community-acquired pneumonia (CAP) greatly increases the risk of long-term morbidity and mortality compared to the general population who have never had CAP, according to a new study from researchers in Canada, the longest and largest outcomes study of patients with CAP reported to date.

“Although the short-term adverse health consequences of CAP are well known, the long-term effects of the disease are less clear,” said Dean T. Eurich, PhD, MSc, BSP, of the University of Alberta in Edmonton, Alberta, Canada. “In our large population-based study of more than 6,000 adults with CAP and almost 30,000 matched controls, we found that CAP patients have high rates of long-term morbidity and mortality compared to those who have never had CAP, irrespective of their age.”

The study was published online ahead of print publication in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

During a median of 9.8 years of follow-up, 2,858 CAP patients died, an absolute risk difference of 30 excess deaths per 1000 patient years of follow-up and a greater that 50% relative increased rate of mortality among CAP patients. Although CAP patients under 25 years of age had the lowest absolute risk difference for mortality, and those over 80 years had the highest absolute risk difference, young CAP adults in fact had the worst relative outcomes of all patients with over a 2-fold increased rate of mortality relative to controls.

The mortality rate was significantly elevated among CAP patients even after including the 406 patients who died within 30 days of the index event and excluding an additional 248 patients who died within 90 days of admission.

In addition to this increased mortality risk, the absolute rates of all-cause hospitalization, emergency department visits, and CAP-related hospital visits, were all significantly higher in CAP patients compared to controls. “Indeed CAP is still considered ‘the old man’s friend’ because of the almost assured high mortality; however our results lend strong support to the alternate proposition that CAP ought to also be considered the young adult’s adversary,” said Eurich.

“Future research may help explain the factors underling these increased long-term risks in CAP patients and inform a treatment approach in these patients,” said Eurich.”Some of these adverse events may be preventable and our results suggest that we have likely underestimated the cost effectiveness, the impact and importance of immunizations that prevent pneumonia.”