Phenotyping community-acquired pneumonia according to the presence of acute respiratory failure and severe sepsis

Abstract

Background: Acute respiratory failure (ARF) and severe sepsis (SS) are possible complications in patients with community-acquired pneumonia (CAP). The aim of the study was to evaluate prevalence, characteristics, risk factors and impact on mortality of hospitalized patients with CAP according to the presence of ARF and SS on admission.

Methods: This was a multicenter, observational, prospective study of consecutive CAP patients admitted to three hospitals in Italy, Spain, and Scotland between 2008 and 2010. Three groups of patients were identified: those with neither ARF nor SS (Group A), those with only ARF (Group B) and those with both ARF and SS (Group C) on admission.

Results: Among the 2,145 patients enrolled, 45% belonged to Group A, 36% to Group B and 20% to Group C. Patients in Group C were more severe than patients in Group B. Isolated ARF was correlated with age (p < 0.001), COPD (p < 0.001) and multilobar infiltrates (p < 0.001). The contemporary occurrence of ARF and SS was associated with age (p = 0.002), residency in nursing home (p = 0.007), COPD (p < 0.001), multilobar involvement (p < 0.001) and renal disease (p < 0.001). 4.2% of patients in Group A died, 9.3% in Group B and 26% in Group C, p < 0.001. After adjustment, the presence of only ARF had an OR for in-hospital mortality of 1.85 (p = 0.011) and the presence of both ARF and SS had an OR of 6.32 (p < 0.001).

Conclusions: The identification of ARF and SS on hospital admission can help physicians in classifying CAP patients into three different clinical phenotypes.

Figure 1

In-hospital mortality of the study population according to the three study groups. Group A: Community-acquired pneumonia (CAP) patients with neither acute respiratory failure (ARF) nor severe sepsis (SS) on admission. Group B: CAP patients with only ARF on admission. Group C: CAP patients with both ARF and SS on admission. n: number.

Figure 2

The cumulative probability of survival in the three study groups. Group A: community-acquired pneumonia (CAP) patients with neither acute respiratory failure (ARF) nor severe sepsis (SS) on admission. Group B: CAP patients with only ARF on admission. Group C: CAP patients with both ARF and SS on admission. Adjusted for centers, sex, age, comorbidities (including congestive heart failure, cerebrovascular accident, diabetes, chronic obstructive pulmonary disease, liver and renal diseases), residence in nursing home, multilobar infiltrate, pleural effusion, empiric antibiotic therapy concordant with European respiratory Society guidelines.

Figure 3

Multivariable logistic model with respect to in-hospital mortality. ARF: acute respiratory failure; SS: severe sepsis; COPD: chronic obstructive pulmonary disease; ABT: antibiotic empiric therapy; ERS: European Respiratory Society; OR: odds ratio; CI: confident intervals. All the variables are present vs. absent, but age (1-year change), male (vs. female) and multilobar (vs. monolobar).

Figure 4

In-hospital mortality in community-acquired pneumonia patients with only acute respiratory failure (ARF) on admission and with both ARF and severe sepsis (SS) on admission stratified by mono- or multilobar involvement on chest X-ray and PaO ₂ /FiO ₂ ratio (P/F) levels on admission.