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Original Research: Chest Infections |

Impact of Age and Comorbidity on Cause and Outcome in Community-Acquired PneumoniaAge, Etiology, and Community-Acquired Pneumonia FREE TO VIEW

Catia Cillóniz, PhD; Eva Polverino, PhD; Santiago Ewig, PhD; Stefano Aliberti, MD; Albert Gabarrús, MSc; Rosario Menéndez, PhD; Josep Mensa, MD; Francesco Blasi, MD; Antoni Torres, PhD, FCCP
Author and Funding Information

From the Department of Respiratory Diseases (Drs Cillóniz, Polverino, and Torres and Mr Gabarrús), Institut del Tórax, Hospital Clinic of Barcelona, IDIBAPS, University of Barcelona, Barcelona, Spain; Centro de Investigación Biomédica En Red-Enfermedades Respiratorias (CibeRes, CB06/06/0028) (Drs Cillóniz, Polverino, Menéndez, and Torres and Mr Gabarrús) Barcelona, Spain; the Department of Infectious Disease (Dr Mensa), Hospital Clinic of Barcelona, IDIBAPS, Barcelona, Spain; the Department of Respiratory Diseases (Dr Menéndez), Hospital La Fe de Valencia, CibeRes, Valencia, Spain; Thoraxzentrum Ruhrgebiet (Dr Ewig), Kliniken für Pneumologie und Infektiologie, EVK Herne und Augusta-Kranken-Anstalt, Bochum, Germany; Dipartimento di Medicina Clinica e Prevenzione (Dr Aliberti), University of Milan-Bicocca, San Gerardo Hospital, Monza, Italy; and Respiratory Medicine Section (Dr Blasi), Dipartimento Toraco-Polmonare e Cardiocircolatorio, University of Milan, IRCCS Fondazione Ca` Granda Ospedale Maggiore, Milan, Italy.

Correspondence to: Antoni Torres, PhD, FCCP, Department of Pneumology, Hospital Clinic of Barcelona, Calle Villarroel 170, Barcelona, Spain; e-mail: atorres@clinic.ub.es


Funding/Support: This study was funded by Ciber de Enfermedades Respiratorias [CibeRes CB06/06/0028] 2009 Support to Research Groups of Catalonia 911.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;144(3):999-1007. doi:10.1378/chest.13-0062
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Background:  Prolonged life expectancy has currently increased the proportion of the very elderly among patients with community-acquired pneumonia (CAP). The aim of this study was to determine the influence of age and comorbidity on microbial patterns in patients over 65 years of age with CAP.

Methods:  This study was a prospective observational study of adult patients with CAP (excluding those in nursing homes) over a 12-year period. We compared patients aged 65 to 74 years, 75 to 84 years, and > 85 years for potential differences in clinical presentation, comorbidities, severity on admission, microbial investigations, causes, antimicrobial treatment, and outcomes.

Results:  We studied a total of 2,149 patients: 759 patients (35.3%) aged 65 to 74 years, 941 patients (43.7%) aged 75 to 84 years, and 449 patients (20.8%) aged > 85 years. At least one comorbidity was present in 1,710 patients (79.6%). Streptococcus pneumoniae was the most frequent pathogen in all age groups, regardless of comorbidity. Staphylococcus aureus, Enterobacteriaceae, and Pseudomonas aeruginosa accounted for 9.1% of isolates, and Haemophilus influenzae, 6.4%. All these pathogens were isolated only in patients with at least one comorbidity. Mortality increased with age (65-74 years, 6.9%; 75-84 years, 8.9%; > 85 years, 17.1%; P < .001) and was associated with increased comorbidities (neurologic; OR, 2.1; 95% CI, 1.5-2.1), Pneumonia Severity Index IV or V (OR, 3.2; 95% CI, 1.8-6.0), bacteremia (OR, 1.7; 95% CI, 1.1-2.7), the presence of a potential multidrug-resistant (MDR) pathogen (S aureus, P aeruginosa, Enterobacteriaceae; OR, 2.4; 95% CI, 1.3-4.3), and ICU admission (OR, 4.2; 95% CI, 2.9-6.1) on multivariate analysis.

Conclusions:  Age does not influence microbial cause itself, whereas comorbidities are associated with specific causes such as H influenzae and potential MDR pathogens. Mortality in the elderly is mainly driven by the presence of comorbidities and potential MDR pathogens.

Prolonged life expectancy in Western countries and medical advances have increased the proportion of patients with community-acquired pneumonia (CAP) at advanced ages and/or with multiple comorbidities.1 These cases have been labeled “CAP in the elderly”14 or “CAP in the very elderly”.5 They clearly present with a lower symptom index, with more severe pneumonia according to risk scores, and have increased mortality.1,2,5 However, conflicting results have been reported regarding microbial sources as a cause of worse outcomes. At least four large European studies found no excess of multidrug-resistant (MDR) pathogens.610 In fact, age and comorbidity, but not etiology, have been shown to be the main determining factors of clinical outcomes of patients with pneumonia in nursing homes (NHs).6 Moreover, von Baum9 analyzed a large CAP series and reported that age > 65 years is a predictive factor for Enterobacteriaceae or Pseudomonas aeruginosa, such as a reduced number of comorbidities (cardiac and cerebrovascular diseases). On the other hand, different studies, all including patients in NHs, have found that comorbidities (cardiovascular and so forth), but not advanced age, are relevant risk factors for gram-negative bacteria.1113 Nevertheless, the influence of comorbidities in the elderly in determining both microbial cause and clinical outcomes of CAP is still unclear. In fact, the evidence of gram-negative infections among patients > 65 years old is poor, and their relation with age itself and comorbidities is not clear. We hypothesized that age itself plays a limited role in determining the microbial cause and mortality of CAP, whereas chronic comorbidities may play a more relevant role. For all these reasons, we analyzed a large population with CAP aged > 65 years and excluded NH as a factor associated with mortality and specific microbial causes in some studies.1113 We, therefore, assessed the impact of age and comorbidity on clinical presentation, cause, and outcomes in three different age groups > 65 years old.

Study Design and Patients

A prospective observational study was carried out in the Hospital Clinic of Barcelona, Spain. All consecutive cases of CAP from November 1996 to July 2008 were included. CAP was defined as the presence of a new infiltrate on chest radiograph and clinical symptoms of lower respiratory tract infection. The exclusion criteria were the following: (1) severe immunosuppression (AIDS, chemotherapy, active neoplasia, immunosuppressive drugs [eg, oral corticosteroids, ≥ 20 mg prednisone or equivalent per day for at least 2 weeks]), (2) active TB, and (3) cases with a confirmed alternative diagnosis. Those cases of witnessed aspirative pneumonia were not included in the database.

Nonhospitalized patients were reexamined after 1 to 7 days in the outpatient clinic. For the purpose of this study, patients in NHs were excluded.

Data Collection

The following data were collected on admission to hospital: age, sex, current smoking (> 10 pack-years), alcohol habits (ingestion of an estimated amount of > 80 g alcohol per day for at least 1 year before presentation), comorbid illnesses, antimicrobial treatment prior to hospital admission, duration of symptoms before the diagnosis of pneumonia, clinical symptoms, physical examination, chest radiograph, pattern, blood analysis, and antimicrobial treatment on admission. All surviving patients were visited or contacted by telephone 30 days after discharge. The Pneumonia Severity Index (PSI)14 and the confusion, urea, respiratory rate, BP, 65 years old (CURB-65)15 scores were determined in all patients. Patients were stratified into low-risk and high-risk classes, as follows: PSI score, low risk = classes I to III, and high risk = class IV to V; CURB-65, low risk = classes 0 to 2 and high risk = classes 3 to 5.

This study was approved by the ethics committees (Register: 2009/5451) of the hospital but patient-informed consent was considered unnecessary because of the observational nature of the study. Details of the microbiologic evaluation and diagnostic criteria have been reported previously.16

Definitions

The study population of patients aged > 65 years with CAP was divided into three age groups (65-74 years, 75-84 years, and ≥ 85 years) for comparison of cause by age and comorbidities. We also divided the study population into three different periods (1996-2000, 2001-2004, and 2005-2008) to analyze possible changes in the characteristics of the population (patient demographics, clinical presentation, site of care, and outcomes over the 12 years of data collection) over the study period. We performed the same analyses for the microorganisms isolated. Comorbidities included the following conditions: chronic respiratory disease, diabetes mellitus, chronic cardiovascular disease, neurologic disease, chronic liver disease, and chronic renal disease.

Statistical Analysis

We show No. (%) for categorical variables and mean (SD) for continuous variables with a normal distribution or median (interquartile range) for those with nonnormal distribution. We compared categorical variables with χ2 or Fisher exact tests, when appropriate. We used the unpaired Student t test or analysis of variance to compare continuous quantitative variables between groups; those with nonnormal distribution were analyzed using the Mann-Whitney U test or the Kruskall-Wallis test. Statistical significance of pairwise comparisons was based on the Bonferroni method. Multivariate logistic regression analyses were performed to assess associations among the age groups, comorbidity, and period with each pathogen. Univariate and multivariate logistic regression analyses were also performed to predict the 30-day hospital mortality (dependent variable). Variables showing a significant result on univariate analysis (P < .1) were included in a multivariate logistic regression backward stepwise model adjusted by age group and period. Highly correlated variables were excluded from multivariate analyses. The Hosmer-Lemeshow goodness-of-fit test was performed to assess the overall fit of the model.17 The level of significance was set at .05 (two-tailed). All statistical analyses were done with SPSS, version 18.0 (IBM).

Patients

Of 3,489 patients with CAP who presented at our hospital during the study period, 2,149 (61.6%) were > 65 years old and were included in the study. The 802 male patients (37.3%) and 1,347 female patients (62.7%) had a mean (SD) age of 78.0 (7.5) years (range, 65-102 years).

Two thousand thirty-one patients (94.5%) were hospitalized (13.5% in ICU), and 118 (5.5%) were treated as outpatients. At least one comorbidity was present in 79.6% of patients (n = 1,710), the most frequent being chronic respiratory disease, with 54.1% (n = 1,152). The distribution of PSI and CURB-65 risk classes was as follows: PSI I to III, 516 (24.1%) and PSI IV or V, 1,625 (75.9%); CURB-65 0 to 2, 1,467 (68.3%) and CURB-65 3 to 5, 682 (31.7%). Overall, the 1-month mortality was 9.9% (n = 213). In general, no significant changes were observed in patient demographics or clinical presentation over the 12 years of data collection, with the exception of some parameters (e-Table 1).

CAP Distribution According to Age Groups

The number of patients with CAP in each age group was as follows: 759 (35.3%) aged 65 to 74 years, 941 (43.7%) aged 75 to 84 years, and 449 (20.8%) aged ≥ 85 years. The main characteristics by age groups are presented in Table 1. The rates of hospitalization for each age group were 91.8% (65-74 years), 95.3% (75-84 years), and 97.3% (≥ 85 years). The corresponding rates of mortality were 6.9%, 8.9%, and 17.1%, respectively (Table 1). The proportion of males decreased with age group, as did the frequency of current smokers and alcohol abuse (P < .001). The rate of the administration of the influenza vaccine increased with every decade (P = .001), whereas no differences were observed for pneumococcal vaccination (P = .50) (Table 1).

Table Graphic Jump Location
Table 1 —General Characteristic by Age Group (N = 2,149)

Data are presented as mean (SD) unless indicated otherwise. Percentages are calculated on nonmissing data. CURB-65 = confusion, urea, respiratory rate, BP, 65 y old; IQR = interquartile range; PSI = Pneumonia Severity Index.

a 

P < .05 for comparison between the groups 65-74 y of age and 75-84 y of age.

b 

P < .05 for comparison between the groups 65-74 y of age and ≥ 85 y of age.

c 

P < .05 for comparison between the groups 75-84 y of age and ≥ 85 yr of age.

d 

Doses of systemic corticosteroids < 10 mg/d.

e 

Percentages calculated for patients with blood culture (566 patients in the group 65-74 y of age, 648 patients in the group 75-84 y of age, and 176 patients in the group ≥ 85 y of age).

Comorbidities

At least one comorbidity was present in 1,710 patients (overall population, 79.6%; 65-74 years, 77.6%; 75-84 years, 80.6%; ≥ 85 years, 80.8; P = .24), with pulmonary comorbidity being the most frequent comorbid condition in the overall population (54.1%) and in all the age groups (Table 1). COPD was the most frequent respiratory comorbidity, decreasing in frequency with age. Among the other relevant comorbidities, diabetes mellitus and chronic liver disease showed a similar decreasing trend with age, whereas cardiovascular, neurologic, and chronic renal failure increased significantly (Table 1), possibly owing to the selection of a healthier “surviving” elderly population.

Severity Score by Age Group and Clinical Outcomes

On admission, the PSI score placed the majority of patients in high-risk classes in all the age groups, whereas CURB-65 scores placed a high proportion of patients in low-risk classes in all the age groups (P < .001). ICU admission and use of mechanical ventilation decreased across the age groups (P < .001), whereas mortality increased (Table 1). The mean length of stay was similar in all the age groups.

Microbial Cause by Age Group and Study Periods

Microbial cause was identified in 856 patients (39.8%). A microbiologic diagnosis decreased constantly with each age group (65-74 years, 332 [43.7%]; 75-84 years, 383 [40.7%]; ≥ 85 years, 141 [31.4%]; P < .001).

Bacteremia was found in 188 patients (8.7% of all cases and 12.6% when expressed in relation to the number of blood cultures available) and was similar in patients from each age group (Table 1). Streptococcus pneumoniae was the most frequent pathogen in all the age groups (40.7%, 39.4%, and 48.9%, respectively), followed by a mixed cause (16.0%, 13.1%, and 10.6%), atypical bacteria (16.0%, 13.1%, and 9.9%), and respiratory viruses (8.4%, 14.6%, and 11.3%). The last were less frequent in the youngest age group (Table 2). No other significant differences could be identified consistently (Table 3, e-Table 2).

Table Graphic Jump Location
Table 2 —Cause by Age Group in Patients With Defined Cause (n = 856)

Data are expressed as No. (%). MRSA = methicillin-resistant Staphylococcus aureus; MSSA = methicillin-sensitive Staphylococcus aureus.

a 

P < .05 for comparison between the groups 65-74 y of age and 75-84 y of age.

b 

P < .05 for comparison between the groups 75-84 y of age and ≥ 85 y of age.

Table Graphic Jump Location
Table 3 —Distribution of Cause (Whole Population) According to Comorbidities by Age Groups (N = 2,149)

Data are expressed as No. (%). See Table 2 legend for expansion of abbreviations.

a 

P values for the model coefficients were derived using the respective logistic regression model for each pathogen as response and with age group, comorbidity, and period as factors.

We did not find significant differences in the distribution of P aeruginosa (6.3%, 4.2%, 2.1%; P = .12); methicillin-resistant Staphylococcus aureus (MRSA) (1.2%, 1.6%, 0%; P = .33) and Enterobacteriaceae (1.2%, 2.6%, 2.8%; P = .341) in all the age groups. Across the study period, we observed only limited changes in the distribution of pathogenic isolates. Only P aeruginosa (from 10.6% to 2.0%) and Haemophilus influenzae (from 12.5% to 2.6%) decreased over time (e-Table 1).

Microbial Cause by Comorbidities

Overall, H influenzae was more frequent in patients with at least one comorbidity, whereas atypical pathogens, particularly Legionella pneumophila, were more frequent in those without comorbidities (Table 3, e-Table 1). Overall, potential MDR pathogens such as S aureus (also MRSA), Enterobacteriaceae, and P aeruginosa were present in 9.1% of cases with a known microbial cause and were found almost exclusively in patients with comorbidities. Similarly, H influenzae, which is found in 6.4% of the global population, was identified mainly in patients with respiratory comorbidities, because 82% of all isolates were found in patients with chronic respiratory diseases (P < .001), particularly COPD (47.3%). Regarding specific comorbidities, no pathogen was consistently found to occur more frequently, regardless of age group.

Bacteremia was more frequent in patients without comorbidities (15.9% vs 11.7% of all positive blood cultures, P = .044) and was more frequent among patients who did not receive pneumococcal vaccination (patients who had not been vaccinated, 86.3%, vs patients who had been vaccinated, 13.7%; P = .010). The rate of administration of the pneumococcal vaccine was greater among patients with comorbidities than among those without (25.8% vs 18.4%, P = .010).

Antimicrobial Treatment

The combination of a β-lactam and macrolide was the most frequent treatment in all the age groups (48.2%, 47.7%, and 50.7%, for 65-74 years, 75-84 years, and ≥ 85 years, respectively), followed by monotherapy with fluoroquinolones in the 65 to 74 years group and 75 to 84 years group (17.7% and 19.7%, respectively) and monotherapy with a β-lactam in the ≥ 85 years age group (16.6%).

Mortality by Cause, Age, and Comorbidity

Two hundred thirteen patients died (10.0%). The mortality rate increased with every decade of life (Table 1). Nonsurvivors were older patients with comorbidities (particularly neurologic disease), a higher severity on admission according to PSI and CURB-65 scores, and a higher rate of bacteremia, and were more frequently admitted to the ICU and received mechanical ventilation (Table 4).

Table Graphic Jump Location
Table 4 —General Characteristics by Mortality (N = 2,149)

Data are expressed as No. (%) unless indicated otherwise. See Table 1 legend for expansion of abbreviations.

a 

Percentages calculated for patients with blood culture (1,358 patients in the survivors group and 132 patients in the nonsurvivors group).

Nonsurvivors more frequently had Enterobacteriaceae (in particular Escherichia coli), whereas atypical and viral causes were more frequent in survivors, regardless of the denominator (whole population [Table 5] or patients with defined cause) (e-Table 3).

Table Graphic Jump Location
Table 5 —Mortality by Cause in the Total Population (n = 2,149)

Data are expressed as No. (%). Potential MDR pathogens include S aureus, E coli, K pneumoniae, Proteus species, P aeruginosa. MDR = multidrug resistant. See Table 2 legend for expansion of other abbreviations.

On multivariate analysis, the factors significantly associated with 30-day mortality were the following: neurologic disease (OR, 2.1; 95% CI, 1.5-2.9; P < .001); PSI score IV or V (OR, 3.2; 95% CI, 1.8-6.0; P < .001); bacteremia (OR, 1.7; 95% CI, 1.1-2.7; P = .015); the presence of a potential MDR pathogen, including S aureus, P aeruginosa, and Enterobacteriaceae (OR, 2.4; 95% CI, 1.3-4.3; P < 0·001); ICU admission (OR, 4.2; 95% CI, 2.9-6.1; P < .001); age > 84 years (OR, 3.3; 95% CI, 2.1-5.0; P < .001); and study period 2005 to 2008 (OR, 0.6; 95% CI, 0.4-0.9; P = .015).

The most important findings of our study are the following: (1) overall, age does not significantly affect pathogen patterns; (2) S pneumoniae was the most frequent pathogen in all the age groups, regardless of the presence of comorbidity; (3) potential MDR pathogens (S aureus, Enterobacteriaceae, and P aeruginosa) were present in 9.1% of the cases diagnosed and occurred almost exclusively in patients with comorbidities, whereas atypical pathogens (including L pneumophila) were more frequent in those without comorbidity; (4) the main factors associated with mortality were neurologic diseases, the presence of a potential MDR pathogen, and very advanced age (> 85 years).

In previous studies evaluating the impact of age on causes in general populations with CAP, Mycoplasma pneumoniae was the main pathogen with a lower incidence in the elderly.18 To determine the precise effect of age, our study excluded patients in NHs, taking into account possible differences across higher age groups. We did not find any notable effect of age on cause in those aged 65 years or over. Thus, age “per se” does not seem to be a relevant criterion for the selection of initial antimicrobial treatment in elderly patients with CAP, clearly in contrast to the hypothesis that age could be a risk factor for potential MDR pathogens.9

Conversely, we found that comorbidities do affect microbial patterns, particularly the incidence of potential MDR pathogens (S aureus, Enterobacteriaceae, and P aeruginosa) and H influenzae. For these reasons, we believe that the choice of antibiotic in the elderly should be based on the risk of MDR pathogens and comorbidities and not on age itself.

The frequency of potential MDR pathogens was moderate in our population, but higher than in other series,9,12 and their association with comorbidities has been suggested previously.1113 Nonetheless, the proportion of very elderly people with comorbidities in our study was much higher than in series including patients with a mean age of 60 to 65 years.9,13,16

Unfortunately, the wide distribution of pathogens within the many defined comorbidities in the three age groups made it impossible to detect associations of specific pathogens with specific comorbidities. H influenzae is thought to be particularly frequent in smokers and patients with COPD and, indeed, it was found to be more frequent among patients with some respiratory comorbidity (82% of all isolates). Bacteremia was also more frequent in patients without comorbidities, likely because of the higher rate of pneumococcal vaccination in the group of comorbidities.

As expected, mortality increased with the number of comorbidities and age, whereas ICU admission decreased, possibly because of treatment-limiting decisions (do-not-resuscitate orders). Nevertheless, the limited access of elderly patients to ICU resources became less frequent over time (from 1996 to 2008), possibly because of prolonged life expectancy in recent years.

As a confirmation, only the very advanced age group (> 85 years) was associated with mortality on multivariate analysis, whereas the presence of potential MDR pathogens was an independent risk factor for death similar to that which has been described in other studies.19 Therefore, we conclude that mortality is mostly related to specific microorganisms and comorbidities.

Interestingly, the last study period (2005-2008) was associated with a lower mortality. This finding may be related to different factors, such as the increasing rate of influenza vaccination and previous antibiotic therapy over time, as well as to the increased rate of ICU admission, possibly reflecting the general trend to extend intensive care maneuvers in elderly people over time. Moreover, the decreasing rate in the frequency of P aeruginosa from 1996 to 2008 may also explain the reduced risk of mortality observed in the last study period.

The main strength of our study is the large population of consecutive patients included over 12 years. To our knowledge, with the exception of one study evaluating patients > 85 years old with CAP,5 this is the first study to systematically analyze and compare different age groups of patients > 65 years of age with CAP. On the other hand, a potential limitation of this study is that microbiologic assessment was not homogeneous over time (particularly for antigen testing) and was less complete in patients ≥ 85 years of age, possibly because of the reduced ability of these patients to expectorate and to less aggressive diagnostic intervention (BAL, an so forth). However, in studies covering long periods and elderly people, such changes may be inevitable.

In conclusion, comorbidities, rather than age, should be considered in the selection of antibiotic treatment of CAP in patients > 65 years of age. Because mortality was significantly associated with the presence of MDR pathogens, prospective studies on specific risk factors of potential MDR pathogens would be welcome.

Author contributions: Dr Torres is the guarantor of the entire manuscript and is responsible for the content of the manuscript, including the data collection and analysis.

Dr Cillóniz: contributed to the review of the study data; writing and editing of the main body of the manuscript; supervision of the collection of clinical, radiologic, and microbiologic data; and approval of the final manuscript.

Dr Polverino: contributed to the supervision of the collection of clinical, radiologic, and microbiologic data and approved the final manuscript.

Dr Ewig: contributed to the design of the project, analysis and interpretation of the results, and editing of the final manuscript.

Mr Gabarrús: contributed to the statistical analysis of the study and review and approval of the final manuscript.

Dr Aliberti: contributed to the design of the project and approval of the final manuscript.

Dr Menéndez: contributed to the design of the project and approval of the final manuscript.

Dr Mensa: contributed to the supervision of the collection of epidemiologic and microbiologic data and approval of the final manuscript.

Dr Blasi: contributed to the design of the project, writing and editing of the main body of the manuscript, and review and approval of the final manuscript.

Dr Torres: contributed to the leading of the study group, the design of the project, approval of the final manuscript, and is the guarantor of the entire manuscript.

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Role of sponsors: CibeRes is an initiative of Carlos III Institute and provides early financial support to selected research groups. GRQ is an initiative of Generalitat of Catalunya and provides partial funding every 5 years for selected research groups.

Additional information: The e-Tables can be found in the “Supplemental Materials” area of the online article.

CAP

community-acquired pneumonia

CURB-65

confusion, urea, respiratory rate, BP, 65 years old

MDR

multidrug-resistant

MRSA

methicillin-resistant Staphylococcus aureus

NH

nursing home

PSI

Pneumonia Severity Index

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Figures

Tables

Table Graphic Jump Location
Table 1 —General Characteristic by Age Group (N = 2,149)

Data are presented as mean (SD) unless indicated otherwise. Percentages are calculated on nonmissing data. CURB-65 = confusion, urea, respiratory rate, BP, 65 y old; IQR = interquartile range; PSI = Pneumonia Severity Index.

a 

P < .05 for comparison between the groups 65-74 y of age and 75-84 y of age.

b 

P < .05 for comparison between the groups 65-74 y of age and ≥ 85 y of age.

c 

P < .05 for comparison between the groups 75-84 y of age and ≥ 85 yr of age.

d 

Doses of systemic corticosteroids < 10 mg/d.

e 

Percentages calculated for patients with blood culture (566 patients in the group 65-74 y of age, 648 patients in the group 75-84 y of age, and 176 patients in the group ≥ 85 y of age).

Table Graphic Jump Location
Table 2 —Cause by Age Group in Patients With Defined Cause (n = 856)

Data are expressed as No. (%). MRSA = methicillin-resistant Staphylococcus aureus; MSSA = methicillin-sensitive Staphylococcus aureus.

a 

P < .05 for comparison between the groups 65-74 y of age and 75-84 y of age.

b 

P < .05 for comparison between the groups 75-84 y of age and ≥ 85 y of age.

Table Graphic Jump Location
Table 3 —Distribution of Cause (Whole Population) According to Comorbidities by Age Groups (N = 2,149)

Data are expressed as No. (%). See Table 2 legend for expansion of abbreviations.

a 

P values for the model coefficients were derived using the respective logistic regression model for each pathogen as response and with age group, comorbidity, and period as factors.

Table Graphic Jump Location
Table 4 —General Characteristics by Mortality (N = 2,149)

Data are expressed as No. (%) unless indicated otherwise. See Table 1 legend for expansion of abbreviations.

a 

Percentages calculated for patients with blood culture (1,358 patients in the survivors group and 132 patients in the nonsurvivors group).

Table Graphic Jump Location
Table 5 —Mortality by Cause in the Total Population (n = 2,149)

Data are expressed as No. (%). Potential MDR pathogens include S aureus, E coli, K pneumoniae, Proteus species, P aeruginosa. MDR = multidrug resistant. See Table 2 legend for expansion of other abbreviations.

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