Lionel A Mandell MD FRCPC1, Thomas J Marrie MD FRCPC2, Ronald F Grossman MD FRCPC FACP3, Anthony W Chow MD FRCPC FACP4, Robert H Hyland MD FRCPC5, and the Canadian CAP Working Group* McMaster University, Hamilton, Ontario; Dalhousie University, Halifax, Nova Scotia; QEII Health Sciences Centre, Halifax, Nova Scotia; University of British Columbia, Vancouver, British Columbia; St Michael’s Hospital, Toronto, Ontario

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Canadian Guidelines for the Initial Management of Community-Acquired Pneumonia: An Evidence-Based Update by the Canadian Infectious Diseases Society and the Canadian Thoracic Society

Community-acquired pneumonia is an important cause of acute respiratory symptoms (eg, cough) in the ambulatory care setting. Distinguishing pneumonia from other causes of respiratory illnesses, such as acute bronchitis and upper respiratory tract infections, has important therapeutic and prognostic implications. The reference standard for diagnosing pneumonia is chest radiography, but it is likely that many physicians rely on the patient's history and their physical examination to diagnose or exclude this disease. A review of published studies of patients suspected of having pneumonia reveals that there are no individual clinical findings, or combinations of findings, that can rule in the diagnosis of pneumonia for a patient suspected of having this illness. However, some studies have shown that the absence of any vital sign abnormalities or any abnormalities on chest auscultation substantially reduces the likelihood of pneumonia to a point where further diagnostic evaluation may be unnecessary. This article reviews the literature on the appropriate use of the history and physical examination in diagnosing community-acquired pneumonia.

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Does this patient have community-acquired pneumonia? Diagnosing pneumonia by history and physical examination.

The initial management of patients suspected of having community-acquired pneumonia is challenging because of the broad range of clinical presentations, potential life-threatening nature of the illness, and associated high costs of care. The initial testing strategies should accurately establish a diagnosis and prognosis in order to determine the optimal treatment strategy. The diagnosis is important in determining the need for antibiotic therapy, and the prognosis is important in determining the site of care. This paper reviews the test characteristics of the history, physical examination, and laboratory findings, individually and in combination, in diagnosing community-acquired pneumonia and predicting short-term risk for death from the infection. In addition, we consider the implications of these test characteristics from the perspective of decision thresholds. The history and physical examination cannot provide a high level of certainty in the diagnosis of community-acquired pneumonia, but the absence of vital sign abnormalities substantially reduces the probability of the infection. Chest radiography is considered the gold standard for pneumonia diagnosis; however, we do not know its sensitivity and specificity, and we have limited data on the costs of false-positive and false-negative results. In the absence of empirical evidence, the decision to order a chest radiograph needs to rely on expert opinion in seeking strategies to optimize the balance between harms and benefits. Once community-acquired pneumonia is diagnosed, a combination of history, physical examination, and laboratory items can help estimate the short-term risk for death and, along with the patient's psychosocial characteristics, determine the appropriate site of treatment.

Testing Strategies in the Initial Management of Patients with Community-Acquired Pneumonia

BACKGROUND: Diagnostic tests enabling general practitioners (GPs) to differentiate rapidly between pneumonia and other lower respiratory tract infections (LRTIs) are needed to prevent increase of bacterial resistance by unjustified antibiotic prescribing. AIMS: To assess the diagnostic value of symptoms, signs, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) for pneumonia; to derive a prediction rule for the presence of pneumonia; and to identify a low-risk group of patients who do not require antibiotic treatment. DESIGN OF STUDY: Cross-sectional. SETTING: Fifteen GP surgeries in the southern part of The Netherlands. METHOD: Twenty-five GPs recorded clinical information and diagnosis in 246 adult patients presenting with LRTI. Venous blood samples for CRP and ESR were taken and chest radiographs (reference standard) were made. Odds ratios, describing the relationships between discrete diagnostic variables and reference standard (pneumonia or no pneumonia) were calculated. Receiver operating characteristic analysis of ESR, CRP, and final models for pneumonia was performed. Prediction rules for pneumonia were derived from multiple logistic regression analysis. RESULTS: Dry cough, diarrhoea, and a recorded temperature of > or = 38 degrees C were independent and statistically significant predictors of pneumonia, whereas abnormal pulmonary auscultation and clinical diagnosis of pneumonia by the GPs were not. ESR and CRP had higher diagnostic odds ratios than any of the symptoms and signs. Adding CRP to the final 'symptoms and signs' model significantly increased the probability of correct diagnosis. Applying a prediction rule for low-risk patients, including a CRP of < 20, 80 of the 193 antibiotic prescriptions could have been prevented with a maximum risk of 2.5% of missing a pneumonia case. CONCLUSION: Most symptoms and signs traditionally associated with pneumonia are not predictive of pneumonia in general practice. The prediction rule for low-risk patients presented here, including a CRP of < 20, can considerably reduce unjustified antibiotic prescribing.

Contributions of symptoms, signs, erythrocyte sedimentation rate, and C-reactive protein to a diagnosis of pneumonia in acute lower respiratory tract infection.

Objectives To quantify the diagnostic accuracy of selected inflammatory markers in addition to symptoms and signs for predicting pneumonia and to derive a diagnostic tool.

Design Diagnostic study performed between 2007 and 2010. Participants had their history taken, underwent physical examination and measurement of C reactive protein (CRP) and procalcitonin in venous blood on the day they first consulted, and underwent chest radiography within seven days.

Setting Primary care centres in 12 European countries.

Participants Adults presenting with acute cough.

Main outcome measures Pneumonia as determined by radiologists, who were blind to all other information when they judged chest radiographs.

Results Of 3106 eligible patients, 286 were excluded because of missing or inadequate chest radiographs, leaving 2820 patients (mean age 50, 40% men) of whom 140 (5%) had pneumonia. Re-assessment of a subset of 1675 chest radiographs showed agreement in 94% (κ 0.45, 95% confidence interval 0.36 to 0.54). Six published “symptoms and signs models” varied in their discrimination (area under receiver operating characteristics curve (ROC) ranged from 0.55 (95% confidence interval 0.50 to 0.61) to 0.71 (0.66 to 0.76)). The optimal combination of clinical prediction items derived from our patients included absence of runny nose and presence of breathlessness, crackles and diminished breath sounds on auscultation, tachycardia, and fever, with an ROC area of 0.70 (0.65 to 0.75). Addition of CRP at the optimal cut off of >30 mg/L increased the ROC area to 0.77 (0.73 to 0.81) and improved the diagnostic classification (net reclassification improvement 28%). In the 1556 patients classified according to symptoms, signs, and CRP >30 mg/L as “low risk” ( 20%), the prevalence of pneumonia was 31%. The positive likelihood ratio of low, intermediate, and high risk for pneumonia was 0.4, 1.2, and 8.6 respectively. Measurement of procalcitonin added no relevant additional diagnostic information. A simplified diagnostic score based on symptoms, signs, and CRP >30 mg/L resulted in proportions of pneumonia of 0.7%, 3.8%, and 18.2% in the low, intermediate, and high risk group respectively.

Conclusions A clinical rule based on symptoms and signs to predict pneumonia in patients presenting to primary care with acute cough performed best in patients with mild or severe clinical presentation. Addition of CRP concentration at the optimal cut off of >30 mg/L improved diagnostic information, but measurement of procalcitonin concentration did not add clinically relevant information in this group.

https://www.bmj.com/content/bmj/346/bmj.f2450.full.pdf

Use of serum C reactive protein and procalcitonin concentrations in addition to symptoms and signs to predict pneumonia in patients presenting to primary care with acute cough: diagnostic study.

Adults presenting to an emergency department with acute respiratory illness were studied prospectively in an effort to identify sensitive clinical criteria for the diagnosis of pneumonia. Of 308 patients studied, 118 (38%) had definite or equivocal infiltrates and were considered to have pneumonia. No single symptom or sign was reliably predictive of pneumonia. Cough was the most common symptom in patients with pneumonia (86%), but was equally common in those with other respiratory illness. Fever was absent in 36 patients with pneumonia (31%). Abnormal findings on lung examination, that is, rales, rhonchi, decreased breath sounds, wheezes, altered fremitus, egophony, and percussion dullness, were each found in fewer than half of the patients with pneumonia. Twenty-six patients (22%) with a completely normal chest examination had pneumonia. Abnormal vital signs (temperature greater than 37.8 degrees C (100 degrees F), pulse greater than 100/min, or respirations greater than 20/min) were 97% sensitive for the detection of pneumonia. These criteria retained their sensitivity when films were subjected to a second, blinded interpretation by a senior radiologist. We conclude that restricting chest roentgenograms to patients with at least one abnormal vital sign will detect almost all radiographically demonstrable pneumonia in adult emergency department patients.

Clinical criteria for the detection of pneumonia in adults: Guidelines for ordering chest roentgenograms in the emergency department

Objective: To determine the frequency of local and systemic adverse reactions following the simultaneous administration of multiple vaccines.

Adverse reactions associated with simultaneous administration of multiple vaccines to travelers

Background The purpose of this study was to determine adult patients' knowledge about their history of age-appropriate routine vaccinations and vaccine preventable diseases.

Methods This was a prospective descriptive study using a self-administered questionnaire. During a 9-month period, all patients older than 18 years of age answered a questionnaire at the time of their first visit to a health department travelers' clinic. Questions included knowledge of vaccines that they might have received (against tetanus, diphtheria, polio, measles, rubella, influenza, and pneumococcus); knowledge of illnesses that they might have had (measles and rubella); incidence of visits to a regular physician; and incidence of chronic illness.

Results Two hundred and twenty patients answered the questionnaire. Eighty-two percent had a regular physician whom they had visited within 5 years. Respondents reported their age-appropriate vaccination history as follows: Td-69%; polio-48%; measles-41%; rubella-38%; influenza-68%; and pneumococcal-13%. For any vaccine, approximately one-third of respondents did not know their status. Age, gender, or a regular source of medical care did not influence the results.

Conclusions Adult patients frequently did not receive, or do not know whether they received, recommended immunizations. Until physicians giving primary medical care improve patient education about vaccination status and develop a better system for having patients keep records of their routine vaccinations, travel clinics will have to function, in part, as primary health care providers.

Cathey Falvo

Papers

Clinical criteria for the detection of pneumonia in adults: Guidelines for ordering chest roentgenograms in the emergency department

Adverse reactions associated with simultaneous administration of multiple vaccines to travelers

Assessment of an Adult Population's Knowledge Regarding Vaccine-Preventable Diseases