Severity prediction rules in community acquired pneumonia: a validation study

Antimicrobial treatment of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a clinical diagnosis that has a significant impact on health care management around the world. Early clinical suspicion and prompt empiric antimicrobial therapies are mandatory in patients with CAP. This article provides a review of recent studies and guidelines addressing antimicrobial therapy for hospitalized patients with CAP.

[Guidelines for the management of community pneumonia in adult who needs hospitalization]

Community acquired pneumonia is still an important health problem. In Spain the year incidence is 162 cases per 100,000 inhabitants with 53,000 hospital admission costing 115 millions of euros per year. In the last years there have been significant advances in the knowledge of: aetiology, diagnostic tools, treatment alternatives and antibiotic resistance. The Spanish Societies of Intensive and Critical Care (SEMICYUC), Infectious Diseases and Clinical Microbiology (SEIMC) and Pulmonology and Thoracic Surgery (SEPAR) have produced these evidence-based Guidelines for the management of community acquired pneumonia in Adults. The main objective is to help physicians to make decisions about this disease. The different points that have been developed are: aetiology, diagnosis, treatment and prevention.

Arterial carbon dioxide tension on admission as a marker of in-hospital mortality in community-acquired pneumonia

PURPOSE

Respiratory failure is the leading cause of death among patients admitted with community-acquired pneumonia. We sought to determine the association between arterial carbon dioxide tension (P(a)CO(2)) and in-hospital mortality in patients admitted with pneumonia.

METHODS

We analyzed data from 2171 patients aged >or=17 years who had been admitted for community-acquired pneumonia to an acute care hospital in Edmonton, Alberta. We compared the risk of all-cause in-hospital mortality using a Cox proportional hazards model across categories of P(a)CO(2).

RESULTS

Overall, in-hospital mortality was 10% (n = 218). Compared with patients with normal P(a)CO(2) values (40 to 44 mm Hg), in-hospital mortality was greater (adjusted odds ratio [OR] = 1.8; 95% confidence interval [CI]: 1.0 to 3.2) among patients with hypocapnia (P(a)CO(2) <32 mm Hg). In-hospital mortality was also greater (OR = 2.6; 95% CI: 1.5 to 4.5) in patients with hypercapnia (>or=45 mm Hg). In-hospital mortality was similar in patients with P(a)CO(2) values between 32 and 35 mm Hg (OR = 1.55; 95% CI: 0.89 to 2.79) and those with values between 36 and 39 mm Hg (OR = 1.42; 95% CI: 0.77 to 2.61).

CONCLUSION

Among patients admitted with community-acquired pneumonia, in-hospital mortality was greater in those with hypocapnia or hypercapnia. These data suggest that measurement of P(a)CO(2) adds prognostic information to standard prediction rules and should be used for clinical and epidemiologic purposes to risk-stratify in-hospital patients with community-acquired pneumonia.

Community-acquired pneumonia: severity of illness evaluation

Severity-of-illness assessment is now an accepted part of clinical practice and clinical research for the management of adults who have community-acquired pneumonia. Several approaches to this issue have been devised based on severity-of-illness scores or rules, some related to site of management. No single approach has been found to be superior to others, but further research into their effect on outcome in clinical practice is required. It is likely that different approaches may suit different populations and health care systems.

Reaching Stability in Community-Acquired Pneumonia: The Effects of the Severity of Disease, Treatment, and the Characteristics of Patients

BACKGROUND

The natural history of the resolution of infectious parameters in patients with community-acquired pneumonia (CAP) is not completely known. The aim of our study was to identify those factors related to host characteristics, the severity of pneumonia, and treatment that influence clinical stability.

METHODS

In a prospective, multicenter, observational study, we observed 1424 patients with CAP who were admitted to 15 Spanish hospitals. The main outcome variable was the number of days needed to reach clinical stability (defined as a temperature of <or=37.2 degrees C, a heart rate of <or=100 beats/min, a respiratory rate of <or=24 breaths/min, systolic blood pressure of >or=90 mm Hg, and oxygen saturation >or=90% or arterial oxygen partial pressure of >or=60 mm Hg).

RESULTS

The median time to stability was 4 days. A Cox proportional hazard model identified 6 independent variables recorded during the first 24 h after hospital admission related to the time needed to reach stability: dyspnea (hazard ratio [HR], 0.76), confusion (HR, 0.66), pleural effusion (HR, 0.67), multilobed CAP (HR, 0.72), high pneumonia severity index (HR, 0.73), and adherence to the Spanish guidelines for treatment of CAP (HR, 1.22). A second Cox model was performed that included complications and response to treatment. This model identified the following 10 independent variables: chronic bronchitis (HR, 0.81), dyspnea (HR, 0.79), confusion (HR, 0.61), multilobed CAP (HR, 0.84), initial severity of disease (HR, 0.73), treatment failure (HR, 0.31), cardiac complications (HR, 0.66), respiratory complications (HR, 0.77), empyema (HR, 0.57), and admission to the intensive care unit (HR, 0.57).

CONCLUSIONS

Some characteristics of CAP are useful at the time of hospital admission to identify patients who will need a longer hospital stay to reach clinical stability. Empirical treatment that follows guidelines is associated with earlier clinical stability. Complications and treatment failure delay clinical stability.

Can chest X-ray predict pneumonia severity?

Predictors of the severity of pneumonia have not been thoroughly evaluated among children in developed countries. We investigate whether chest radiographic findings could be used as predictors of severity of childhood pneumonia. The study included 167 children, aged more than 12 months, hospitalized in our department during a 4-year period with unilateral lobar or segmental pneumonia. The durations of fever and of hospitalization were considered indicators of severity of the disease. The size of the consolidation and its location in the left hemithorax were independently associated with severity of the disease. Univariate analysis showed that the mean duration of fever and of hospitalization as well as the prevalence of pleural effusion was significantly higher among children with left-sided pneumonia. A multiple logistic regression analysis revealed that only the presence of pleural effusion was significantly more likely in left-sided pneumonia (odds ratio, 2.65; 95% confidence interval, 1.09-6.47; P = 0.031). We conclude that the size of consolidation and the side of its location can be used as predictors of severity of pneumonia, with left-sided pneumonia running a more severe course, possibly due to increased risk for the development of pleurisy.

Validation of predictive rules and indices of severity for community acquired pneumonia

BACKGROUND

A study was undertaken to validate the modified American Thoracic Society (ATS) rule and two British Thoracic Society (BTS) rules for the prediction of ICU admission and mortality of community acquired pneumonia and to provide a validation of these predictions on the basis of the pneumonia severity index (PSI).

METHOD

Six hundred and ninety six consecutive patients (457 men (66%), mean (SD) age 67.8 (17.1) years, range 18-101) admitted to a tertiary care hospital were studied prospectively. Of these, 116 (16.7%) were admitted to the ICU.

RESULTS

The modified ATS rule achieved a sensitivity of 69% (95% CI 50.7 to 77.2), specificity of 97% (95% CI 96.4 to 98.9), positive predictive value of 87% (95% CI 78.3 to 93.1), and negative predictive value of 94% (95% CI 91.8 to 95.8) in predicting admission to the ICU. The corresponding predictive indices for mortality were 94% (95% CI 82.5 to 98.7), 93% (95% CI 90.6 to 94.7), 49% (95% CI 38.2 to 59.7), and 99.5% (95% CI 98.5 to 99.9), respectively. These figures compared favourably with both the BTS rules. The BTS-CURB criteria achieved predictions of pneumonia severity and mortality comparable to the PSI.

CONCLUSIONS

This study confirms the power of the modified ATS rule to predict severe pneumonia in individual patients. It may be incorporated into current guidelines for the assessment of pneumonia severity. The CURB criteria may be used as an alternative tool to PSI for the detection of low risk patients.

Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study

BACKGROUND

In the assessment of severity in community acquired pneumonia (CAP), the modified British Thoracic Society (mBTS) rule identifies patients with severe pneumonia but not patients who might be suitable for home management. A multicentre study was conducted to derive and validate a practical severity assessment model for stratifying adults hospitalised with CAP into different management groups.

METHODS

Data from three prospective studies of CAP conducted in the UK, New Zealand, and the Netherlands were combined. A derivation cohort comprising 80% of the data was used to develop the model. Prognostic variables were identified using multiple logistic regression with 30 day mortality as the outcome measure. The final model was tested against the validation cohort.

RESULTS

1068 patients were studied (mean age 64 years, 51.5% male, 30 day mortality 9%). Age >/=65 years (OR 3.5, 95% CI 1.6 to 8.0) and albumin <30 g/dl (OR 4.7, 95% CI 2.5 to 8.7) were independently associated with mortality over and above the mBTS rule (OR 5.2, 95% CI 2.7 to 10). A six point score, one point for each of Confusion, Urea >7 mmol/l, Respiratory rate >/=30/min, low systolic(<90 mm Hg) or diastolic (</=60 mm Hg) Blood pressure), age >/=65 years (CURB-65 score) based on information available at initial hospital assessment, enabled patients to be stratified according to increasing risk of mortality: score 0, 0.7%; score 1, 3.2%; score 2, 3%; score 3, 17%; score 4, 41.5% and score 5, 57%. The validation cohort confirmed a similar pattern.

CONCLUSIONS

A simple six point score based on confusion, urea, respiratory rate, blood pressure, and age can be used to stratify patients with CAP into different management groups.

The pathophysiological significance of prognostic factors for fatal outcome in lower respiratory tract infections

OBJECTIVE

The aim of this study was to determine prognostic factors for outcome in patients with lower respiratory tract infections (LRTI). LRTI are an heterogeneous group of disorders, including acute bronchitis, pneumonia, superinfection of chronic bronchitis and influenza.

METHODOLOGY

A total of 616 patients with LRTI were retrospectively reviewed with regard to epidemiological, clinical, laboratory and radiographical data. Prognostic analysis included a univariate as well as a multivariate approach, in order to identify parameters associated with death.

RESULTS

The parameters found to be significantly different between survivors and non-survivors in the univariate analysis, were respiratory rate, PaO2, heart rate, systolic and diastolic blood pressure, platelet count, urea, creatinine, previous admission to the hospital in the last year and cavitations visible on the chest radiograph.

CONCLUSIONS

LRTI remain a widespread problem and have a significant impact on primary healthcare resources. The great variability seen in rates of hospital admission and lengths of stay in part reflects uncertainty among physicians in assessing the severity of the illness. According to our data, PaO2 and heart rate were most closely associated with patient death and are readily defined and available at presentation.

[Pneumonia in the patient with chronic obstructive pulmonary disease. Levels of severity and risk classification]

OBJECTIVES

To analyze the severity, clinical course and mortality in patients with community-acquired pneumonia and COPD.

METHOD

Retrospective study of patients admitted with pneumonia over a period of 12 months. From records, we gathered information related to patient characteristics, signs and symptoms and concomitant disease and classified each patient according to risk.

RESULTS

One hundred twenty-nine patients with a mean age of 71.13 (SD 17) were identified; 43 (33.3%) had COPD with severe airflow obstruction (FEV1 937 mL, SD 309), although there were no differences from one risk classification to another. No significant differences were found in mortality, as 8 patients (18.6%) with COPD died and 9 patients (10.7%) without COPD. The length of hospital stay was similar in both groups. Patients with COPD suffered more severe pneumonia and were at higher risk (classes IV and V). The percentage of COPD patients using chronic domiciliary oxygen therapy who died (75%) was different from the percentage of such patients who lived (37%); percent mortality also differed by level of risk. Patients receiving oxygen therapy had greater obstruction and greater respiratory insufficiency upon admission (PaO2/FiO2: 216.9, SD 41.92).

CONCLUSIONS

The mortality rates and mean hospital stays of patients with and without COPD who are admitted with community-acquired pneumonia are similar, but patients with COPD suffer more severe pneumonia. Mortality is higher in patients with community-acquired pneumonia and COPD who are receiving domiciliary oxygen therapy and have greater airflow obstruction and respiratory deterioration upon admission.

Community-acquired pneumonia in elderly patients

CAP in elderly patients carries a significant economic and clinical burden and will be more commonly encountered in the future as the US population ages. Diagnosis may be obscured by a nonclassic presentation in an elderly patient, and the clinician needs to be especially suspicious of pneumonia whenever the clinical status of an elderly patient deteriorates. The single most important clinical decision is the site of care; this determination is not always based on clinical factors but also on social factors. Severity assessment is key to stratifying appropriate therapy and to predicting outcome. Timely and appropriate empiric therapy enhances the likelihood of a good clinical outcome, although clinical resolution may be more delayed than in younger patients. Newly emerging patterns of antibiotic resistance have altered recent guidelines for CAP treatment; DRSP is now a consideration in elderly patients because an age older than 65 years is a well-described risk factor for infection with this organism. Prevention should always be implemented, with a focus on pneumococcal and influenza vaccination.

[Community-acquired pneumonia in the elderly: prognostic factors]

The incidence and mortality rates of community-acquired pneumonia are far higher in the elderly than among younger populations. However, the explanation may lie in the presence of comorbidity rather than in age itself. We performed a retrospective study of 226 patients over the age of 65 years who were admitted to our hospital with a diagnosis of community-acquired pneumonia over a period of 36 months, with the objective of identifying factors predicting mortality and to describe clinical features. The patients' mean age was 78.71 (65-96) years. One hundred forty-two were men (63%) and 84 were women (37%). Upon admission, 27.4% showed signs of altered mental state. The crude mortality rate was 20.8%. Multivariate analysis demonstrated the following independent risk factors associated with higher mortality: serum creatinine > 1.2 mg/dL (RR = 13.93; 95% CI 8.14-16.08); patient previously bedridden (RR = 5.73; 95% CI 3.41-6.79), PaO2/FiO2 < 200 (RR = 5; 95% CI 2.67-6.62) and neoplastic disease (RR = 4.08; 95% CI 1.96-5.24). The presence of chest pain was associated with a lower risk of mortality (RR = 0.11; 95% CI 0.01-0.54). Age itself was not a risk factor. We conclude that pneumonia in the elderly requires hospitalization and that it commonly presents with severe symptoms and high risk of mortality. Risk factors such as those identified in this study may help in the diagnosis and treatment of patients requiring special care.

Respiratory rate measurement in adults--how reliable is it?

Measurement of respiratory rate (RR) is essential in the evaluation of respiratory disorders. However, the variability in RR measurement in adults has never been adequately assessed. Respiratory rate was measured twice in 245 patients; the two measurements were performed by the same observer in 137 patients, by different observers in 58 patients and simultaneously by different observers in 50 patients. The mean (SD) difference between the first and second measurements was 0.03 (3); 95% limits of agreement-4.86-4.94 breaths min(-1), -5.7-5.7 breaths min(-1), and -4.2 to 4.4 breaths min(-1) for the same observer, different observer and simultaneous observer groups, respectively. The difference in RR measurements did not vary with RR. In conclusions on average, there is very good agreement between observers in RR measurement. Inter-observer variability may account for a difference of up to 6 breaths min(-1). This is relevant when applying clinical prediction rules based on threshold RR values.

Defining severe community-acquired pneumonia

Based on the recognition of the main pathophysiologic features of pneumonia and currently available data on prognosis and clinical severity assessment, key points for a definition of severe pneumonia are as follows: 1. Independent predictors of pneumonia severity are factors reflecting acute respiratory failure and severe sepsis or septic shock. 2. In view of the dependence of the development of acute respiratory failure on pulmonary comorbidities, radiographic extension may prove to be an additional independent predictor of severe respiratory compromise. 3. Vital sign abnormalities other than acute respiratory failure and severe hypotension may be independent predictors of severity, particularly in patients presenting in early and asymptomatic stages of severe sepsis. 4. Several pathogens have been shown to have adverse prognostic potential. Because the cause is unknown at the initial evaluation, however, pathogens cannot form part of the criteria for the initial severity assessment. 5. Because pneumonia is a dynamic process, any assessment of severity takes place at an arbitrary point of disease evolution. It would be desirable to define a set of parameters reflecting initial severity as well as a state of increased risk for early deterioration toward severe pneumonia. 6. Severity stratification within the population of patients with severe pneumonia may open the prospect of identifying patients who may have the greatest benefit from intensive care.

How should we make the admission decision in community-acquired pneumonia?

The spectrum of pneumonia patients ranges from only slightly compromised patients to patients who require life-sustaining measures. Admission decision support algorithms usually are not required for patients at either end of the spectrum. For patients presenting with intermediate severity of illness, decision support algorithms have shown that they can support clinicians in the admission decision and complement the clinicians' experience and clinical judgment with an objective tool. Clinical information systems may help overcome the existing obstacles to successful implementation. Successful guideline implementation in a clinical setting includes strategies that target not only the disease, but also include other forces that significantly influence the admission decision. Shared decision making and better managing of patients' expectations about treatment and prognosis need to be incorporated in the overall admission decision. The availability of improved outpatient management, such as outpatient intravenous antibiotic treatment and home health care, and a change in physicians' perspectives and patients' expectations may help to increase the proportion of outpatient management without compromising the quality of care. Decision support tools for pneumonia are available and show promising results. Further studies are needed, however, that show the successful dissemination and clinical implementation during routine patient care. Studies are needed that assess the impact of guidelines and prediction rules on patient outcomes. As the example of the PSI shows, the development, implementation, and dissemination of admission decision support systems is not a revolutionary, but a stepwise, evolutionary process that requires many years of research.

Pneumonia in the elderly

Pneumonia, including community-acquired, LTCF-acquired, and nosocomial infections, is a major cause of morbidity and mortality among the elderly. The aged with pneumonia often present with atypical features, including confusion, lethargy, and general deterioration of condition (silent infection). Further investigations, such as a chest radiograph frequently are required for diagnosis. The chest radiograph may be normal early on in the course of infection, particularly in dehydrated patients. The elderly are hospitalized more frequently for pneumonia, have a greater need for intravenous therapy, have a longer hospital stay, have a more prolonged course, have greater morbidity, and ultimately have a poorer outcome. Nevertheless, it may not be chronologic age per se that has a negative impact on the manifestations and outcome of pneumonia in the elderly, but rather the presence of underlying comorbid illness. The mainstay of therapy for pneumonia is antibiotics, and studies in the community and hospital have confirmed the important positive impact of early appropriate empiric therapy on outcome. Many relatively simple procedures, including attention to nutrition, influenza and pneumococcal vaccination, and avoidance of intubation, may help limit the occurrence of such infections.

Management of parapneumonic pleural effusion

Parapneumonic pleural effusion is a common and potentially serious complication of pneumonia. The management of parapneumonic pleural effusion involves early diagnosis, adequate empiric antibiotic cover, and appropriate risk categorization. High-risk patients require safe and expedient drainage of the infected pleural space. The management options include thoracentesis, tube thoracostomy, adjunctive intrapleural fibrinolytic therapy, and surgical drainage. The methods of surgical drainage include thoracoscopy, thoracotomy, and decortication. The relative clinical efficacy of these treatment options has been studied in a small number of controlled clinical trials, the results of which have been systematically reviewed by expert panels. Based on the limited clinical evidence, expert reviewers were unable to recommend a best method of pleural drainage. However, the consensus is that an aggressive approach with early surgical drainage results in shorter hospital stays and may be more cost-effective than conservative management. This review discusses the clinical evidence and describes an aggressive sequential management strategy that combines intrapleural fibrinolysis with early surgical drainage.

Study of community acquired pneumonia aetiology (SCAPA) in adults admitted to hospital: implications for management guidelines

BACKGROUND

Since the last British study of the microbial aetiology of community acquired pneumonia (CAP) about 20 years ago, new organisms have been identified (for example, Chlamydia pneumoniae), new antibiotics introduced, and fresh advances made in microbiological techniques. Pathogens implicated in CAP in adults admitted to hospital in the UK using modern and traditional microbiological investigations are described.

METHODS

Adults aged 16 years and over admitted to a teaching hospital with CAP over a 12 month period from 4 October 1998 were prospectively studied. Samples of blood, sputum, and urine were collected for microbiological testing by standard culture techniques and new serological and urine antigen detection methods.

RESULTS

Of 309 patients admitted with CAP, 267 fulfilled the study criteria; 135 (50.6%) were men and the mean (SD) age was 65.4 (19.6) years. Aetiological agents were identified from 199 (75%) patients (one pathogen in 124 (46%), two in 53 (20%), and three or more in 22 (8%)): Streptococcus pneumoniae 129 (48%), influenza A virus 50 (19%), Chlamydia pneumoniae 35 (13%), Haemophilus influenzae 20 (7%), Mycoplasma pneumoniae 9 (3%), Legionella pneumophilia 9 (3%), other Chlamydia spp 7 (2%), Moraxella catarrhalis 5 (2%), Coxiella burnetii 2 (0.7%), others 8 (3%). Atypical pathogens were less common in patients aged 75 years and over than in younger patients (16% v 27%; OR 0.5, 95% CI 0.3 to 0.9). The 30 day mortality was 14.9%. Mortality risk could be stratified by the presence of four "core" adverse features. Three of 60 patients (5%) infected with an atypical pathogen died.

CONCLUSION

S pneumoniae remains the most important pathogen to cover by initial antibiotic therapy in adults of all ages admitted to hospital with CAP. Atypical pathogens are more common in younger patients. They should also be covered in all patients with severe pneumonia and younger patients with non-severe infection.

Defining prognostic factors in the elderly with community acquired pneumonia: a case controlled study of patients aged > or = 75 yrs

Severity assessment in the elderly with community acquired pneumonia (CAP) may be different compared with younger patients. In particular, age per se may not be of prognostic significance in older patients. A case-control study in 158 patients aged > or = 75 yrs with CAP was conducted to determine the factors associated with in-hospital mortality. Cases were drawn from all patients aged > or = 75 yrs with CAP who died in 1997 in five hospitals in the mid-Trent region of the UK (Nottingham City Hospital, University Hospital Nottingham, Derby Royal Infirmary, Derby City General Hospital and Kings Hill Hospital). Controls were randomly selected from survivors also aged > or = 75 yrs. Factors associated with mortality were identified following a review of the medical casenotes and the contribution of these factors to mortality was determined using multivariate analysis. Absence of fever, tachycardia and chest radiograph features of bilateral involvement or an effusion were independently associated with mortality on multivariate analysis. The British Thoracic Society (BTS) severity rule was 50% sensitive and 64% specific in predicting death while the modified BTS rule displayed 67% sensitivity and 58% specificity. Age was not significantly associated with mortality in this group of patients aged > or = 75 yrs. Similarly, the clinical features employed in the British Thoracic Society rule, namely respiratory rate, diastolic blood pressure and blood urea, were not of prognostic significance and the rule itself performed poorly. The modified British Thoracic Society rule performed better.

Radiological-pathological correlation: alveolar pattern

This review summarizes important pathological lesions of the lung that typically present radiographically with an 'alveolar pattern'. For each entity, the latest findings as to its pathogenesis, aetiology and pathology are reviewed in the introductory remarks. We then present the typical radiological appearances alongside macroscopic and microscopic pathological photographs. It is hoped that the parallel presentation of radiological image with the pathology will enhance the understanding of the diverse range of diseases the aevolar pattern comprises.

A national confidential enquiry into community acquired pneumonia deaths in young adults in England and Wales. British Thoracic Society Research Committee and Public Health Laboratory Service

BACKGROUND

The aim of this study was to describe the frequency, causal pathogens, management, and outcome of a population of young adults who died from community acquired pneumonia (CAP).

METHODS

Pneumonia deaths in England and Wales in adults aged 15-44 were identified between September 1995 and August 1996. Patients with underlying chronic illness including HIV infection were excluded. Clinical details for each case were collected from the hospital and general practitioner records.

RESULTS

Death from CAP was identified in 27 previously well young adults (1.2 per million population per year). Twenty were known to have consulted a GP for this illness. Nine received antibiotics before hospital admission. A causative pathogen was identified in 17 cases (Streptococcus pneumoniae in eight). Bacteraemia was present in seven. All patients who reached a hospital ward received antibiotics (69% within two hours of admission). The British Thoracic Society antibiotic guidelines for severe CAP were followed in only 10 cases. Cardiac arrest at home or on arrival at hospital occurred in six cases, one of whom was successfully resuscitated. Of the remaining 21 patients, 71% had two or more markers of severe CAP. All 22 who were admitted reached an intensive care unit, but 11 of these required transfer to another hospital for some aspect of intensive care. One third of patients died within 24 hours of presenting to the hospital.

CONCLUSIONS

Death from CAP in previously fit young adults still occurs. While some deaths might be preventable by better patient management, most are unlikely to be preventable by current management practices.