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1 Hospital Joan XXIII, Universitat Rovira i Virgili/Institut Pere Virgili, Tarragona, 2 Hospital Clinic, Barcelona, 4 Hospital Dr. Negrín, Las Palmas de Gran Canária, 5 Hospital Virgen del Rocio, Sevilla, 6 Hospital Virgen Victoria, Málaga, and 7 Hospital Joseph Trueta, Girona, Spain, 3 Hospital Verge de Meritxell, Andorra.
CORRESPONDENCE: J. Rello, Critical Care Dept, Joan XXIII University Hospital, Carrer Mallafre Guasch 4, E43007 Tarragona, Spain. Fax: 34 977295878. E-mail: jordi.rello{at}urv.net
Keywords: Community-acquired pneumonia
Received: November 25, 2005
Accepted February 7, 2006
| ABSTRACT |
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The current authors performed a secondary analysis of a prospective study evaluating 428 immunocompetent patients admitted to the intensive care unit (ICU) for severe CAP.
In total, 176 COPD patients were compared with 252 non-COPD patients. In COPD patients, ICU mortality (odds ratio (OR) 1.58; 95% confidence interval (CI) 1.011.43) and mechanical ventilation (OR 2.78; 95% CI 1.634.74) rates were higher than in non-COPD patients. The ICU mortality was 39% for COPD patients initially intubated and 50% for those who failed noninvasive ventilation. The proportion of patients who were males, aged
70 yrs, smokers and who had chronic heart disease or Pseudomonas aeruginosa were higher in COPD patients. Inappropriate empirical antibiotic therapy was associated with higher mortality (OR 3.8; 95% CI 1.1912.6). ICU mortality in COPD patients with adequate therapy was associated with bilateral pneumonia (OR 2.32; 95% CI 1.184.53) and shock (OR 3.53; 95% CI 1.319.71).
In conclusion, chronic obstructive pulmonary disease patients hospitalised with community-acquired pneumonia in the intensive care unit had higher mortality and need of mechanical ventilation when compared with patients without chronic obstructive pulmonary disease.
A strong association between chronic obstructive pulmonary disease (COPD) and severe community-acquired pneumonia (SCAP), mainly caused by Streptococcus pneumoniae or Haemophilus influenzae, has been suggested 1, 2. For COPD in particular, this elevated incidence appears to be explained by altered pulmonary defence mechanisms 3. Fekety et al. 4 reported a higher incidence of pneumococcal pneumonia in COPD patients than in control patients.
COPD is one of the most frequent comorbidities in patients admitted to hospital for CAP and respiratory failure 1, 511. In a prospective study of SCAP in 529 patients in 33 intensive care units (ICUs) in Spain, COPD was the most frequent comorbidity 12. Therefore, a secondary analysis was conducted with the primary objective of comparing the demographic characteristics, aetiology and outcome of patients admitted to the ICU for SCAP with and without a prior diagnosis of COPD. A specific goal was to examine if the presence of COPD was a predictor for increased mortality in ICU patients hospitalised for pneumonia. A secondary objective was to assess how the use of noninvasive ventilation (NIV) influenced outcome. The current authors' hypothesis was that COPD patients with SCAP will have a higher ICU mortality and risk of mechanical ventilation than other immunocompetent patients hospitalised in the ICU with SCAP without COPD.
| METHODS |
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The enrolled patients were consecutive cases aged
18 yrs, with conclusive evidence of pneumonia as primary diagnosis, confirmed by chest radiography. The study focused on patients in the ICU and excluded patients with respiratory infections other than pneumonia (for example, exacerbated COPD patients), and those on home oxygen therapy. Immunocompromised patients (i.e. patients with HIV infection, neoplasia, those taking cytotoxic drugs or long-term oral steroid therapy, such as daily doses of >20 mg of prednisolone or the equivalent for >2 weeks) were excluded, as well as patients with asthma, interstitial lung diseases or aspiration pneumonia. Patients with COPD criteria were enrolled in this sub-study. Appropriate therapy was defined as the use of at least one antibiotic to which all isolates were susceptible in vitro or (for Pneumocystis jiroveci or Legionella pneumophila) were expected to be susceptible. Pre-existing COPD was defined as a disease state characterised by the presence of airflow limitation due to chronic bronchitis or emphysema. The airflow obstruction may be accompanied by airway hyperreactivity and may be partially reversible 13. Details of other definitions, including pneumonia or shock, among others, have been reported elsewhere 12. A patient was considered to be a smoker if they had smoked more than one packet per day within the past 10 yrs 14. Mechanical ventilation included invasive ventilation and NIV.
A wide range of demographic, clinical and laboratory measures were recorded in each patient, as described previously. In the current study, particular emphasis was placed on the age of the patients, history of smoking, presence of other comorbidities, and severity of illness measured by the acute physiological score (APS) of Acute Physiology And Chronic Health Evaluation (APACHE) II score.
Patients in whom standard treatment or NIV was not successful underwent endotracheal intubation. Variables considered as indicating unsuccessful standard treatment or NIV have been reported previously 15 and included: failure to maintain an arterial oxygen tension/inspiratory oxygen fraction of >85; need to protect the airways; inability to spontaneously clear tracheal secretions; agitation requiring sedation; inability to tolerate the face mask; an increase in the arterial carbon dioxide accompanied by a pH <7.20; or septic shock. Treatment decisions for all study participants, including determination of the need for intubation or mechanical ventilation, were made by the primary clinical teams.
An organism was considered to be a "definitive" aetiological agent only if it was isolated from blood or pleural fluid, or if serological tests revealed a four-fold increase in antibody levels. Isolation of P. jiroveci or culture of L. pneumophila or Mycobacterium tuberculosis was considered the basis of a "definitive" diagnosis, in accordance with current guidelines 16, 17. Microorganisms isolated from other cultures, including bronchoscopic samples, or with a positive urinary antigen test were considered as "probable" 16, 17.
Discrete variables were expressed as counts (%) and continuous variables as mean±SD, unless stated otherwise. All statistical tests were two-sided. Differences in categorical variables were calculated using a two-sided likelihood ratio Chi-squared test for nondichotomous categorical variables and a two-sided Fisher's exact test for dichotomous variables. The KaplanMeier estimate-of-survival curve was used to determine the probability of survival for COPD and non-COPD patients at 28 days. Survival curves were compared using the log-rank test. Cox proportional hazards regression was used to adjust for severity of the impact of independent variables on ICU mortality. Factors associated with increased mortality by bivariate analysis (p
0.05) were entered into the model. A p-value <0.05 was considered as significant. In addition to p-values, odds ratios (OR) and 95% confidence intervals (CI) were calculated.
| RESULTS |
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The most frequent antibiotic treatments in COPD patients were: cephalosporines plus macrolide (n = 93, 52.9%), cephalosporines; plus fluoroquinolone (n = 33, 18.8%), other combinations (n = 9, 5.2%); and monotherapy (n = 41, 23.8%). Time until the first antibiotic dose was estimated to be 6.6±10.1 h. Details of antibiotic regimens are shown in table 2
. In total, 80 (45.4%) COPD patients received empirical anti-pseudomonal therapy and the ICU mortality rate (32.5%) was similar to episodes receiving other regimens (28.1%). No differences in ICU mortality rate were observed between COPD patients who received combination therapy or monotherapy (30.4% versus 29.3%; p = 0.95). ICU mortality rate did not significantly differ with the use of a fluoroquinolone (31.4% versus 29.5%; p = 0.93) or a macrolide (26.5% versus 34.6%; p = 0.31) as part of the empirical regimen. Finally, antibiotic treatment was modified in 77 (43.7%) episodes: 23 due to de-escalation, 14 due to inappropriate treatment and 40 due to poor resolution (table 2
). A bacterial pathogen was identified in 17 (12 caused by S. pneumoniae) of these episodes with changes of antibiotic therapy due to poor resolution and 20 (50%) of them ultimately died.
| DISCUSSION |
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Previous studies in COPD patients have suggested that Chlamydia pneumoniae is a frequent cause of SCAP 11, 19. In the present study, other atypical agents, such as Mycoplasma pneumoniae, or common organisms of the normal respiratory tract in COPD 20, 21, e.g. Moraxella catarrhalis, were infrequently identified. This is probably due to the difference of severity in episodes requiring ICU admission. S. pneumoniae remained the most frequent pathogen and the leading cause in fatal episodes, emphasising COPD patients should be administered anti-pneumococcal vaccinations. Nontypable H. influenzae was the third most prevalent pathogen, but an uncommon cause of death. Viruses are important agents of COPD exacerbation but none were identified, although systematic samples from nasal airways were not investigated.
P. aeruginosa was the second most common organism in patients with COPD and this is another aspect of interest. Moreover, incidence was significantly higher than in non-COPD patients and it appears to be a near exclusive problem in COPD patients. However, only 7.4% of COPD patients had P. aeruginosa and the current authors were unable to anticipate potential variables identifying COPD patients at high risk of P. aeruginosa.
The pulmonary severity index (PSI) defined from the Pneumonia Outcomes Research Team study 22 includes five comorbid conditions (cardiovascular, malignancy, cerebrovascular, renal and liver diseases), but does not include COPD as one of them. This score was designed in a cohort of patients who included a minority of patients requiring ICU admission and was primarily designed to influence the decision to hospitalise the patient. In addition, in the PSI score, COPD was analysed together with asthma and interstitial lung disease, which could be a reason why it was not identified as a risk factor for poor outcome. Another multicentre study in Spain 11 reported low overall mortality for COPD patients with pneumonia. However, all COPD patients with pneumonia were hospitalised and <20% needed ventilatory support. In contrast, nearly 90% of the current cohort required mechanical ventilation. This group represents only a small proportion of hospitalised COPD patients, but it is the one with the highest mortality rates.
The present study confirms that it is crucial for physicians to initiate correct treatment if the risk of mortality is not to increase. The multivariate analysis failed to identify intervention-related factors that were able to improve survival in the subset receiving agents with adequate sensitivity. However, this study was not designed for this purpose. Moreover, factors other than the simple concept of in vitro activity alone play key roles in fighting infection. Waterer et al. 23 suggested that monotherapy may be suboptimal for patients with bacteraemic S. pneumoniae pneumonia, whatever treatment is given. Further studies 2427 agree with these findings, but the controversy should be resolved by conducting a randomised clinical trial.
There were some limitations to the current study. First, it was not possible to record data regarding lung function tests or COPD disease severity. Although they can be used to classify severity and assess clinical response, these tests are usually not suitable in ICU patients 7, 28. Further prospective cohort studies should determine the impact of COPD severity on survival and microbiology. Secondly, as in other studies exploring combination therapy, these results were not from a randomised controlled study. However, severity of illness measured by APS was identical. The present study cohort comprised patients with severe episodes of pneumonia requiring intensive care. Therefore, the current findings should not be extrapolated to COPD patients with pneumonia requiring hospitalisation in medical wards or with acute exacerbation. Immunocompromised patients were excluded and the current findings cannot be extrapolated to COPD patients with long-term oral steroid treatment, in whom the pathogen responsible may be an opportunistic microorganism. Patients included in the current study did not receive steroids in routine clinical practice, even those associated with septic shock. The effect of steroids in pneumonia should be further evaluated as part of randomised clinical trials. Finally, follow-up did not extend beyond the ICU stay and the continued drop in survival after ICU discharge is well documented 29. However, the optimal time-frame for the ascertainment of mortality should be that during which the intervention can plausibly be expected to affect survival and should encompass the potential impact of the intervention. Indeed, short-term survival can be considered a surrogate measure. In addition, long-term survival is confounded by deaths from other causes 30.
In conclusion, the present study demonstrates significantly higher mortality rates among patients with chronic obstructive pulmonary disease who require intensive care unit admission for acute respiratory failure due to severe community-acquired pneumonia. This selected population of patients has a higher need for mechanical ventilation and a higher incidence of Pseudomonas aeruginosa than non-chronic obstructive pulmonary disease patients.
| ACKNOWLEDGEMENTS |
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J. Solé: Dr Negrin Hospital, Gran Canaria; J. Blanquer: Clinic Hospital, Valencia; J. Jiménez: Virgen del Rocio, Sevilla; V. de la Torre, Virgen de la Victoria Hospital, Malaga; J.M. Sirvent: Josep Trueta Hospital, Girona; M. Bodí: Joan XXIII Hospital, Tarragona; J. Almirall: Mataró Hospital, Mataró, Barcelona; A. Doblas: Juan Ramon Jimenez Hospital, Huelva; J.R. Badía: Clinic Hospital Barcelona, Barcelona; F. García: General Hospital, Albacete; A. Mendia: Nuestra Señora de Aranzazu Hospital, San Sebastian; R. Jordá: Son Dureta Hospital, Palma de Mallorca; F. Bobillo: Clinico Hospital, Valladolid; J. Vallés: Hospital Parc Tauli, Sabadell, Barcelona; M.J. Broch: Sagunto Hospital, Valencia; N. Carrasco: Princesa Hospital, Madrid; M.A. Herranz: Rio Hortega Hospital, Valladolid; F. Alvarez Lerma: Del Mar Hospital, Barcelona; E. Mesalles: Trias I Pujol Hopsital, Badalona, Barcelona; B. Alvarez: General Hospital, Alicante; J.C. Robles: Reina Sofia Hospital, Córdoba; E. Maraví: Virgen del camino hospital, Pampalona; F. Barcenilla: Arnau de Vilanova Hospital, Lleida; M.A. Blasco: Peset Aleixandre Hospital, Valencia; G. Masdeu: Verge de la Cinta Hospital, Tortosa, Tarragona; M.J. López Pueyo: General de Yagüe Hospital, Burgos; A. Margarit: Virgen Meritxell Hospital, Andorra; J. Fierro: Poniente Hospital, Almeria; F. Renedo: Leon Hospital, Leon; A. Lores: Bellvitge Hospital, Barcelona; R. Alonso: General de Asturias Hospital, Oviedo; M.J. Huertos: Puerto Real Hospital, Cadiz; M.J. López Cambra: General Hospital, Segovia.
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