The study, by Dr. Eric Mortensen of the University of Texas Health Sciences Center in San Antonio, published in the December 15 issue of Clinical Infectious Diseases, identifies factors that appear to play a significant role in long-term mortality following an episode of acute pneumonia. Patients who survived the initial episode of pneumonia for at least 90 days, and who did not have HIV infection, were enrolled and followed for an average of almost 6 years. Factors predicting an increased risk of death during the follow-up period included age, nutritional status, preexisting illnesses ("comorbidity"), nursing home residence, male sex, and less than a college education. The severity of the pneumonia was not a predictive factor in long-term mortality. In fact, patients with a lower grade of fever on presentation had a higher long-term mortality than those with a higher grade of fever. Overall, in this multicenter study, about one-third of patients who survived for 90 days died over the next 6 years.
Previous studies have examined this issue but were generally smaller in size and often did not distinguish short-term mortality, presumably from the pneumonia, from long-term mortality, arising from other factors. Although the presence of other illnesses (comorbidity) might seem to be the logical explanation for the increased risk of death, some studies, like this one, have found that comorbidity is not the whole answer. Unfortunately, many of the other risk factors for increased long-term mortality are related to intrinsic characteristics of the patient, and are largely unchangeable by medical care.
An accompanying editorial in the same issue, written by Dr. Thomas Marrie of the University of Alberta, points out that some of the factors that might be helpful in fighting the acute pneumonia could be detrimental in the long run. For example, some patients seem to respond to infection with a more pronounced inflammatory reaction than others. While this might help in the acute situation, such factors might accelerate other processes such as arteriosclerosis (hardening of the arteries) over longer periods. However, these hypotheses remain speculative.
Founded in 1979, Clinical Infectious Diseases publishes clinical articles twice monthly in a variety of areas of infectious disease, and is one of the most highly regarded journals in this specialty. It is published under the auspices of the Infectious Diseases Society of America (IDSA), based in Alexandria, Va., a professional society representing more than 7,000 physicians and scientists who specialize in infectious diseases.