A number of members of the Pneumonia Editorial Board engaged in a discussion and were in agreement that the lack of an accepted and widely used definition or classification of pneumonia is a significant problem. However, there was less agreement on how pneumonia should be defined and classified and how this issue should be tackled. Perspectives from high-income settings included the poor correlation between radiologic appearance and systems for International Classification of Disease ICD for hospital admissions, and an appeal for a definition that recognises certain aspects particular to older adults.
The diagnosis of pneumonia in the intensive care setting was noted as being particularly unreliable, although the evolving use of lung ultrasound offers more clarity. The Editorial Board members who participated in the discussion would most likely agree that pneumonia is an acute infection distinguishable from chronic infections, although this should not be confused with several other acute lower respiratory tract infections with well-recognised and distinguishable patterns, such as bronchiolitis and bronchitis.
So, how can the field of pneumonia care and research overcome the current lack of clarity concerning definition and classification? There was a call to reach a consensus on definitions of pneumonia in both resource-limited and well-resourced settings.
Pneumonia was first described by Hippocrates [ 5 ] — BC. The first descriptions of its clinical and pathological features were made 22 centuries later in by Laennec [ 6 ] while Rokitansky [ 7 ] in was the first to differentiate lobar and bronchopneumonia. During the next 47 years at least 28 terms were used to identify pneumonia [ 8 ], and by the total number of terms listed in the Manual of the International List of Causes of Death had grown to 94, with 12 sub-terms [ 9 ].
ICD codes usually include subcategories so there are still many classifications for pneumonia. It states that pneumonia is not a single disease but a group of specific infections, each with a different epidemiology, pathogenesis, presentation and clinical course [ 11 ].
The lack of accepted, widely understood and commonly used definition s for pneumonia causes a fundamental problem where related but heterogeneous pathologies and clinical phenotypes are poorly classified. The lack of clear classification results in difficulty with clinical decision making and a potential for poorly formulated research.
The magnitude of this problem is most evident in the common inability to identify the infectious organism s causing lung infection, necessitating empiric antibiotic therapy. If a specific diagnosis could be made, specific therapy could be provided which would be of similar efficacy to empiric wide spectrum therapy [ 13 ] and avoid millions of prescriptions of broad-spectrum antibiotics and the associated risks of antibiotic resistance.
The magnitude of the problem is less evident in the field of pneumonia research. In a qualitative sense, the problem may be distilled to a lack of homogeneity in clinical and pathological phenotypes under investigation. In studies of heterogeneous groups the research problems that may arise include an inability to determine aetiology due to a limited range of methods; pathology or microbiology with disparate patterns; and conflicting results between studies that investigate risk factors, diagnostic methods or treatments.
Heterogeneous groups may result in disparate and unfocused studies, which fail to target the most important types of pneumonia and the most important questions, and make limited contributions. In epidemiologic terms, investigation of heterogeneous groups will, to a lesser or greater extent, threaten the internal validity of studies. When heterogeneous groups are studied, invalid estimates of effect occur due to misclassification bias [ 14 ].
In the field of pneumonia research, determining aetiology is a common difficulty. For example, in the absence of specimens from the lung, studies of aetiology may misclassify causality to organisms detected in nasopharyngeal or sputum samples—in this situation, misclassification bias occurs due to the difficulty in accurately determining the aetiology of lung infection.
However, taken to an extreme, the pursuit of representativeness can defeat the goal of identifying causal biological relations. In laboratory science, it is routine for investigators to conduct experiments using animals with characteristics selected to enhance the validity of the experimental work rather than to represent a target population.
Concerns about generalisability only become important after it is accepted that the study results are valid for the restricted group. Likewise, epidemiologic study designs are stronger if participant selection is guided by the need to make a valid comparison, which may call for severe restriction of eligibility to a narrow range of characteristics, rather than attempting to make the participants generally representative [ 14 ].
To minimise the threats to the validity of research outlined above, homogeneous study groups should be selected with respect to clinical phenotype, pathology and important confounders. Once effect estimates are established by studies designed to maximise validity, generalisation to other groups becomes simpler. To a large extent, generalisation is a question of whether the factors that distinguish populations from the study group somehow modify the effect in question.
To answer this question, epidemiologic data will be of help, but other sources of information such as pathophysiology may also play an important role. In relation to pneumonia research, the internal validity of studies will be improved if participants are more homogenous with respect to factors associated with the outcome. For example, when comparing antibacterial therapies in patients with pneumonia, the internal validity of the study will be improved if the patient group is restricted to those with a proven bacterial cause; antibacterial therapy cannot benefit patients with viral pneumonia.
The question of generalising study results to wider populations is a separate consideration. Heterogeneity of research participants is not always bad and may be required when findings need to be generalised to wider populations. The focus here is to illustrate the value of studying homogenous groups when the current lack of clarity in the classification of pneumonia results in a tendency towards the inclusion of heterogenous groups.
Two examples of pneumonia research that have substantially advanced the field illustrate the scientific benefit of using restrictive criteria to study homogenous patient subgroups.
To attain a homogeneous group of participants, research studies must classify patients according to some given criteria. It is clear that all of the systems of classification have significant deficiencies, primarily relating to an inability to determine the aetiology of cases of pneumonia, and substantial heterogeneity of aetiology, phenotype and pathology. A theme also emerges where the classification systems that are designed to guide clinical care and treatment e.
Given that empiric prescription of antibiotics and antimicrobial resistance are such a concern and that pneumonia research using definitions and classifications that lead to substantial heterogeneity is relatively common, it would appear that a fresh perspective would benefit the field. The aim of this commentary is to stimulate debate towards consensus classifications for clinical terminology, separating bronchiolitis from pneumonia, examining the value of the community- and hospital-acquired classification, and purposeful refinement of classifications based on microbiology, aetiology, radiology, severity, complications, important age groups and subgroups.
In the interim, better ways to determine the aetiology of pneumonia need to be sought, and researchers should consider the benefits of using methods of classification to provide more homogeneous groups, the study of which is likely to provide clearer answers to research questions.
The radiologic diagnosis of pneumonia in children. Article Google Scholar. Aston SJ. The role of rapid diagnostic tests in managing adults with pneumonia in low-resource settings. Rylance J, Waitt P. Pneumonia severity scores in resource poor settings. Rasanen J, Gavriely N. Childhood pneumonia screener: a concept. The genuine works of Hippocrates, In: Translated from the Greek with a preliminary discourse and annotations by Francis Adams.
London: Sydenham Society; Google Scholar. Laennec RT. A treatise on the diseases of the chest and on mediate auscultation.
In: Translated from the 3rd French ed. Forbes, with notes of Prof. Andral from the 4th ed. Wood; Rokitansky C. Inflammations of the lungs pneumoniae. In: Manual of Pathological Anatomy. Wells EF. Introduction to study of pneumonic fever. United States Bureau of the Census. Manual of the international list of causes of death: based on the fourth decenial revision by the International Commission, Paris, October 16 to 19, Washington: Government Printing Office; ICD Version.
Accessed 9 Dec Levison ME. New York: McGraw-Hill; Effect of age, polymicrobial disease, and maternal HIV status on treatment response and cause of severe pneumonia in South African children: a prospective descriptive study. Comparison between pathogen directed antibiotic treatment and empirical broad spectrum antibiotic treatment in patients with community acquired pneumonia: a prospective randomised study. Validity in Epidemiologic Studies, Ch 9. Modern epidemiology. Standardization of interpretation of chest radiographs for the diagnosis of pneumonia in children.
Accessed 3 Oct World Health Organisation. Revised WHO classification and treatment of childhood pneumonia at health facilities - Evidence Summaries. Mild signs and symptoms often are similar to those of a cold or flu, but they last longer.
Newborns and infants may not show any sign of the infection. Or they may vomit, have a fever and cough, appear restless or tired and without energy, or have difficulty breathing and eating. See your doctor if you have difficulty breathing, chest pain, persistent fever of F 39 C or higher, or persistent cough, especially if you're coughing up pus. For some older adults and people with heart failure or chronic lung problems, pneumonia can quickly become a life-threatening condition.
Many germs can cause pneumonia. The most common are bacteria and viruses in the air we breathe. Your body usually prevents these germs from infecting your lungs. But sometimes these germs can overpower your immune system, even if your health is generally good. Pneumonia is classified according to the types of germs that cause it and where you got the infection.
Community-acquired pneumonia is the most common type of pneumonia. It occurs outside of hospitals or other health care facilities. It may be caused by:. Some people catch pneumonia during a hospital stay for another illness.
Hospital-acquired pneumonia can be serious because the bacteria causing it may be more resistant to antibiotics and because the people who get it are already sick. People who are on breathing machines ventilators , often used in intensive care units, are at higher risk of this type of pneumonia.
Health care-acquired pneumonia is a bacterial infection that occurs in people who live in long-term care facilities or who receive care in outpatient clinics, including kidney dialysis centers. Like hospital-acquired pneumonia, health care-acquired pneumonia can be caused by bacteria that are more resistant to antibiotics. Aspiration pneumonia occurs when you inhale food, drink, vomit or saliva into your lungs.
Aspiration is more likely if something disturbs your normal gag reflex, such as a brain injury or swallowing problem, or excessive use of alcohol or drugs. Even with treatment, some people with pneumonia, especially those in high-risk groups, may experience complications, including:.
Examples of pneumonia in a Sentence He caught pneumonia over the winter. Recent Examples on the Web One of the child mummies interred in the catacombs that was previously examined by researchers is that of Rosalia Lombardo, who died of pneumonia at the age of two in Wang, New York Times , 25 Dec. First Known Use of pneumonia , in the meaning defined above.
Buying Guide Our team at The Usage has selected the best pulse oximeters. Learn More About pneumonia. Time Traveler for pneumonia The first known use of pneumonia was in See more words from the same year.
From the Editors at Merriam-Webster. Style: MLA. English Language Learners Definition of pneumonia.
0コメント