Antibiotics and mortality in patients with lower respiratory infection and advanced dementia.

OBJECTIVES: To describe long-term mortality rate and to assess associations between mortality rate and antibiotic treatment of lower respiratory infection in patients with advanced dementia; antibiotic treatment allocation was independent of mortality risk-leaving less room for biased associations than in previous multicenter observational studies.

DESIGN: Prospective study (2004-2009). Multilevel Cox proportional hazard analyses with adjustment for mortality risk were used to assess associations between antibiotics and mortality using time-dependent covariates.

SETTING: A US Department of Veterans Affairs nursing home.

PARTICIPANTS: Ninety-four residents with advanced dementia who developed 109 episodes.

MEASUREMENTS: Survival, treatment, mortality risk, illness severity, fluid intake, and several other patient characteristics.

RESULTS: Ten-day mortality was 48%, and 6-month mortality was 74%. Antibiotics were used in 77% of episodes. Overall, antibiotics were not associated with mortality rate (Hazard Ratio [HR] 0.70, Confidence Interval [CI] 0.38-1.30); however, antibiotics were associated with reduced 10-day mortality rate (HR 0.51, CI, 0.30-0.87; rate after 10 days: 1.5, CI 0.42-5.2). Benefit from antibiotics was less likely with inadequate fluid intake, and when experiencing the first episode.

CONCLUSION: In our sample of male nursing home residents with advanced dementia and lower respiratory infection, mortality was substantial despite antibiotic treatment. Antibiotics prolonged life but in many cases only for several days. Treatment decisions should take into account that antibiotics may delay death but may also prolong the dying process, indicating a need for accurate prediction of mortality and study of characteristics that may alter effectiveness of antibiotics.