Definition, Epidemiology, and Pathogenesis of Severe Community-Acquired Pneumonia.

The clinical presentation of community-acquired pneumonia (CAP) can vary widely among patients. While many individuals with mild symptoms can be managed as outpatients with excellent outcomes, there is a distinct subgroup of patients who present with severe CAP. In these cases, the mortality rate can reach approximately 25% within 30 days and even up to 50% within a year. It is crucial to focus attention on these patients who are at higher risk. Among the various definitions of severe CAP found in the literature, one commonly used criterion is the requirement for admission to intensive care unit. Notable epidemiological characteristics of these patients include the impact of acute cardiovascular diseases on clinical outcomes and the enduring, independent effect of pneumonia on long-term outcomes. Factors such as pathogen virulence, the presence of comorbidities, and the host response are important contributors to the pathogenesis of severe CAP. In these patients, the host response may be dysregulated and compartmentalized. Gaining a better understanding of the epidemiology and pathogenesis of severe CAP will provide a foundation for the development of new therapies for this condition. This manuscript aims to review the definition, epidemiology, and pathogenesis of severe CAP, shedding light on important aspects that can aid in the improvement of patient care and outcomes.

Misdiagnosis of Clostridioides difficile Infections by Standard-of-Care Specimen Collection and Testing among Hospitalized Adults, Louisville, Kentucky, USA, 2019-20201.

Although Clostridioides difficile infection (CDI) incidence is high in the United States, standard-of-care (SOC) stool collection and testing practices might result in incidence overestimation or underestimation. We conducted diarrhea surveillance among inpatients >50 years of age in Louisville, Kentucky, USA, during October 14, 2019-October 13, 2020; concurrent SOC stool collection and CDI testing occurred independently. A study CDI case was nucleic acid amplification test‒/cytotoxicity neutralization assay‒positive or nucleic acid amplification test‒positive stool in a patient with pseudomembranous colitis. Study incidence was adjusted for hospitalization share and specimen collection rate and, in a sensitivity analysis, for diarrhea cases without study testing. SOC hospitalized CDI incidence was 121/100,000 population/year; study incidence was 154/100,000 population/year and, in sensitivity analysis, 202/100,000 population/year. Of 75 SOC CDI cases, 12 (16.0%) were not study diagnosed; of 109 study CDI cases, 44 (40.4%) were not SOC diagnosed. CDI incidence estimates based on SOC CDI testing are probably underestimated.

Severity of Illness Scores and Biomarkers for Prognosis of Patients with Coronavirus Disease 2019.

The spectrum of disease severity and the insidiousness of clinical presentation make it difficult to recognize patients with coronavirus disease 2019 (COVID-19) at higher risk of worse outcomes or death when they are seen in the early phases of the disease. There are now well-established risk factors for worse outcomes in patients with COVID-19. These should be factored in when assessing the prognosis of these patients. However, a more precise prognostic assessment in an individual patient may warrant the use of predictive tools. In this manuscript, we conduct a literature review on the severity of illness scores and biomarkers for the prognosis of patients with COVID-19. Several COVID-19-specific scores have been developed since the onset of the pandemic. Some of them are promising and can be integrated into the assessment of these patients. We also found that the well-known pneumonia severity index (PSI) and CURB-65 (confusion, uremia, respiratory rate, BP, age ≥ 65 years) are good predictors of mortality in hospitalized patients with COVID-19. While neither the PSI nor the CURB-65 should be used for the triage of outpatient versus inpatient treatment, they can be integrated by a clinician into the assessment of disease severity and can be used in epidemiological studies to determine the severity of illness in patient populations. Biomarkers also provide valuable prognostic information and, importantly, may depict the main physiological derangements in severe disease. We, however, do not advocate the isolated use of severity of illness scores or biomarkers for decision-making in an individual patient. Instead, we suggest the use of these tools on a case-by-case basis with the goal of enhancing clinician judgment.

Machine-Aided Bridge Deck Crack Condition State Assessment Using Artificial Intelligence.

The Federal Highway Administration (FHWA) mandates biannual bridge inspections to assess the condition of all bridges in the United States. These inspections are recorded in the National Bridge Inventory (NBI) and the respective state's databases to manage, study, and analyze the data. As FHWA specifications become more complex, inspections require more training and field time. Recently, element-level inspections were added, assigning a condition state to each minor element in the bridge. To address this new requirement, a machine-aided bridge inspection method was developed using artificial intelligence (AI) to assist inspectors. The proposed method focuses on the condition state assessment of cracking in reinforced concrete bridge deck elements. The deep learning-based workflow integrated with image classification and semantic segmentation methods is utilized to extract information from images and evaluate the condition state of cracks according to FHWA specifications. The new workflow uses a deep neural network to extract information required by the bridge inspection manual, enabling the determination of the condition state of cracks in the deck. The results of experimentation demonstrate the effectiveness of this workflow for this application. The method also balances the costs and risks associated with increasing levels of AI involvement, enabling inspectors to better manage their resources. This AI-based method can be implemented by asset owners, such as Departments of Transportation, to better serve communities.

Association and predictive value of biomarkers with severe outcomes in hospitalized patients with SARS-CoV-2 infection.

This study analyzed the levels at admission of biomarkers for their association with and ability to predict risk of severe outcomes, including admission to the ICU, need for invasive mechanical ventilation (IMV), need for vasopressor use (VU), and in-hospital mortality (IHM) in 700 patients hospitalized with COVID-19. Biomarker data split by outcomes was compared using Mann-Whitney U tests; frequencies of biomarker values were compared using Chi-square tests and multivariable logistic regression analysis was performed to look at the impact of biomarkers by outcome. Patients that suffered IHM were more likely to have reduced platelet numbers and high blood urea nitrogen (BUN) levels among patients admitted to the ICU. Risk factors for mortality were related to hyper-coagulability (low platelet count and increased D-dimer) and decreased respiratory (PaO2/FiO2 ratio) and kidney function (BUN). Association with risks of other severe outcomes were as follows: ICU with hyper-inflammation (IL-6) and decreased respiratory function; IMV with low platelet count, abnormal neutrophil-lymphocyte ratio with reduced respiratory function, VU with inflammatory markers (IL-6), and low platelet count with respiratory function. Our studies confirmed the association of biomarkers of hematological, inflammatory, coagulation, pulmonary and kidney functions with disease severity. Whether these biomarkers have any mechanistic or causal role in the disease progress requires further investigation.

Effectiveness of oseltamivir treatment on clinical failure in hospitalized patients with lower respiratory tract infection.

BACKGROUND: Influenza is associated with excess morbidity and mortality of individuals each year. Few therapies exist for treatment of influenza infection, and each require initiation as early as possible in the course of infection, making efficacy difficult to estimate in the hospitalized patient with lower respiratory tract infection. Using causal machine learning methods, we re-analyze data from a randomized trial of oseltamivir versus standard of care aimed at reducing clinical failure in hospitalized patients with lower respiratory tract infection during the influenza season. METHODS: This was a secondary analysis of the Rapid Empiric Treatment with Oseltamivir Study (RETOS). Conditional average treatment effects (CATE) and 95% confidence intervals were computed from causal forest including 85 clinical and demographic variables. RETOS was a multicenter, randomized, unblinded, trial of adult patients hospitalized with lower respiratory tract infections in Kentucky from 2009 through 2012. Adult hospitalized patients with lower respiratory tract infection were randomized to standard of care or standard of care plus oseltamivir as early as possible after hospital admission but within 24 h of enrollment. After randomization, oseltamivir was initiated in the treatment arm per package insert. The primary outcome was clinical failure, a composite measure including failure to reach clinical improvement within 7 days, transfer to intensive care 24 h after admission, or rehospitalization or death within 30 days. RESULTS: A total of 691 hospitalized patients with lower respiratory tract infections were included in the study. The only subgroup of patients with a statistically significant CATE was those with laboratory-confirmed influenza infection with a 26% lower risk of clinical failure when treated with oseltamivir (95% CI 3.2-48.0%). CONCLUSIONS: This study suggests that addition of oseltamivir to standard of care may decrease clinical failure in hospitalized patients with influenza-associated lower respiratory tract infection versus standard of care alone. These results are supportive of current recommendations to initiate antiviral treatment in hospitalized patients with confirmed or suspected influenza as soon as possible after admission. Trial registration Original trial: Clinical Trials.Gov; Rapid Empiric Treatment With Oseltamivir Study (RETOS) (RETOS); ClinicalTrials.gov Identifier: NCT01248715 https://clinicaltrials.gov/ct2/show/NCT01248715.

Effect of Bamlanivimab vs Placebo on Incidence of COVID-19 Among Residents and Staff of Skilled Nursing and Assisted Living Facilities: A Randomized Clinical Trial.

Importance: Preventive interventions are needed to protect residents and staff of skilled nursing and assisted living facilities from COVID-19 during outbreaks in their facilities. Bamlanivimab, a neutralizing monoclonal antibody against SARS-CoV-2, may confer rapid protection from SARS-CoV-2 infection and COVID-19. Objective: To determine the effect of bamlanivimab on the incidence of COVID-19 among residents and staff of skilled nursing and assisted living facilities. Design, Setting, and Participants: Randomized, double-blind, single-dose, phase 3 trial that enrolled residents and staff of 74 skilled nursing and assisted living facilities in the United States with at least 1 confirmed SARS-CoV-2 index case. A total of 1175 participants enrolled in the study from August 2 to November 20, 2020. Database lock was triggered on January 13, 2021, when all participants reached study day 57. Interventions: Participants were randomized to receive a single intravenous infusion of bamlanivimab, 4200 mg (n = 588), or placebo (n = 587). Main Outcomes and Measures: The primary outcome was incidence of COVID-19, defined as the detection of SARS-CoV-2 by reverse transcriptase-polymerase chain reaction and mild or worse disease severity within 21 days of detection, within 8 weeks of randomization. Key secondary outcomes included incidence of moderate or worse COVID-19 severity and incidence of SARS-CoV-2 infection. Results: The prevention population comprised a total of 966 participants (666 staff and 300 residents) who were negative at baseline for SARS-CoV-2 infection and serology (mean age, 53.0 [range, 18-104] years; 722 [74.7%] women). Bamlanivimab significantly reduced the incidence of COVID-19 in the prevention population compared with placebo (8.5% vs 15.2%; odds ratio, 0.43 [95% CI, 0.28-0.68]; P < .001; absolute risk difference, -6.6 [95% CI, -10.7 to -2.6] percentage points). Five deaths attributed to COVID-19 were reported by day 57; all occurred in the placebo group. Among 1175 participants who received study product (safety population), the rate of participants with adverse events was 20.1% in the bamlanivimab group and 18.9% in the placebo group. The most common adverse events were urinary tract infection (reported by 12 participants [2%] who received bamlanivimab and 14 [2.4%] who received placebo) and hypertension (reported by 7 participants [1.2%] who received bamlanivimab and 10 [1.7%] who received placebo). Conclusions and Relevance: Among residents and staff in skilled nursing and assisted living facilities, treatment during August-November 2020 with bamlanivimab monotherapy reduced the incidence of COVID-19 infection. Further research is needed to assess preventive efficacy with current patterns of viral strains with combination monoclonal antibody therapy. Trial Registration: ClinicalTrials.gov Identifier: NCT04497987.

The elevated systemic cytokine levels in HIV patients are not associated with an elevated pulmonary cytokine environment.

BACKGROUND: HIV-positive patients on anti-retroviral therapy (ART) are at higher risk of developing many non-AIDS related chronic diseases, including chronic obstructive pulmonary disease (COPD), compared to HIV-negative individuals. While the mechanisms are not clear, a persistent pro-inflammatory state appears to be a key contributing factor. The aims of this study were to investigate whether HIV-positive patients without COPD present evidence of potentially predisposing abnormal pulmonary cytokine/chemokine environment and to explore the relationship between pulmonary and systemic cytokine levels. METHODS: This study included 39 HIV-seropositive and 34 HIV-seronegative subjects without COPD. All were subjected to outpatient bronchoscopy with bronchoalveolar lavage fluid (BALF) aspiration and blood sample collection. The levels of 21 cytokines and chemokines were measured in plasma and BALF using a bead-based multi-analyte assay. RESULTS: In plasma, HIV-infected patients showed significantly increased circulating levels of pro-inflammatory (TNFα) and Th1-associated cytokines (IL-12p70) as well as several chemokines (CXCL11 and CX3CL1). However, no statistically significant differences were found in the numbers of cells, the concentrations of protein and urea as well as cytokine levels in the BALFs of HIV-positive patients when compared to controls. Correlation analysis indicated a potential modulatory effect of the BMI in HIV-seropositive individuals. CONCLUSIONS: While our results are consistent with the existence of a systemic pro-inflammatory state in HIV-infected patients, they did not detect significant differences in cytokine levels and other inflammatory markers in the lungs of HIV-positive individuals when compared to HIV-negative controls.

Patients with Obesity Have Better Long-Term Outcomes after Hospitalization for COPD Exacerbation.

Obesity has been shown to have a paradoxical benefit in a number of conditions, but the long-term effects in obesity after chronic obstructive pulmonary disease (COPD) exacerbation is still unclear. In this study, the effects of obesity on short- and long-term outcomes after a COPD exacerbation were evaluated. This was a secondary analysis of the Rapid Empiric Treatment with Oseltamivir Study (RETOS): a prospective, randomized, unblinded clinical trial. Patients were included in the study if they were hospitalized for acute exacerbation of COPD. Obesity was noted as patients with BMI >30. Clinical outcomes of time to clinical stability, length of stay, and mortality were compared. A total of 301 patients were included in the study, 122 (41%) patients were obese. There was no significant difference in the length of stay and time to clinical stability between patients with and without obesity. Mortality for patients with and without obesity was 3% and 3% at 30 days, 7% and 18% at six months, and 8% and 28% at one year, respectively. After adjusting with multivariable regression analysis, patients with obesity had a significant reduction in odds of dying at one year (adjusted odds ratio (aOR): 0.18; 95% CI: 0.06-0.58; p = .004) and at six months (aOR: 0.28; 95% CI: 0.09-0.89; p = .031). Our study showed that obesity was associated with reduced mortality at one year and six months after a COPD exacerbation. Although patients with obesity had higher rates of comorbidities, they had reduced mortality at one year after multivariable regression analysis.

Early Clinical Response in Community-acquired Bacterial Pneumonia: From Clinical Endpoint to Clinical Practice.

BACKGROUND: Early clinical response (ECR) is a new endpoint to determine whether a drug should be approved for community-acquired bacterial pneumonia in the United States. The Omadacycline for Pneumonia Treatment In the Community (OPTIC) phase III study demonstrated noninferiority of omadacycline to moxifloxacin using this endpoint. This study describes the performance of the ECR endpoint and clinical stability relative to a posttreatment evaluation (PTE) of clinical success. METHODS: ECR was defined as symptom improvement 72-120 hours after the first dose of study drug (ECR window), no use of rescue antibiotics, and patient survival. Clinical success at PTE was an investigator assessment of success. Clinical stability was defined based on vital sign stabilization, described in the American Thoracic Society and Infectious Diseases Society of America community-acquired pneumonia treatment guidelines. RESULTS: During the ECR window, ECR was achieved in 81.1% and 82.7% of omadacycline and moxifloxacin patients, respectively. Similar numbers of patients achieved clinical stability in each treatment group (omadacycline 74.6%, moxifloxacin 77.6%). The proportion of patients with improved symptoms who were considered clinically stable increased across the ECR window (69.2-77.6% for omadacycline; 68.0-79.7% for moxifloxacin). There was high concordance (>70%) and high positive predictive value (>90%) of ECR and clinical stability with overall clinical success at PTE. CONCLUSIONS: Omadacycline was noninferior to moxifloxacin, based on a new ECR endpoint. Clinical stability was similarly high when measured in the same time frame as ECR. Both ECR and clinical stability showed high concordance and high positive predictive value with clinical success at PTE. CLINICAL TRIALS REGISTRATION: NCT02531438.

Future Research Directions in Pneumonia. NHLBI Working Group Report.

Pneumonia is a complex pulmonary disease in need of new clinical approaches. Although triggered by a pathogen, pneumonia often results from dysregulations of host defense that likely precede infection. The coordinated activities of immune resistance and tissue resilience then dictate whether and how pneumonia progresses or resolves. Inadequate or inappropriate host responses lead to more severe outcomes such as acute respiratory distress syndrome and to organ dysfunction beyond the lungs and over extended time frames after pathogen clearance, some of which increase the risk for subsequent pneumonia. Improved understanding of such host responses will guide the development of novel approaches for preventing and curing pneumonia and for mitigating the subsequent pulmonary and extrapulmonary complications of pneumonia. The NHLBI assembled a working group of extramural investigators to prioritize avenues of host-directed pneumonia research that should yield novel approaches for interrupting the cycle of unhealthy decline caused by pneumonia. This report summarizes the working group's specific recommendations in the areas of pneumonia susceptibility, host response, and consequences. Overarching goals include the development of more host-focused clinical approaches for preventing and treating pneumonia, the generation of predictive tools (for pneumonia occurrence, severity, and outcome), and the elucidation of mechanisms mediating immune resistance and tissue resilience in the lung. Specific areas of research are highlighted as especially promising for making advances against pneumonia.

Effectiveness of 13-Valent Pneumococcal Conjugate Vaccine Against Hospitalization for Community-Acquired Pneumonia in Older US Adults: A Test-Negative Design.

Background: Following universal recommendation for use of 13-valent pneumococcal conjugate vaccine (PCV13) in US adults aged ≥65 years in September 2014, we conducted the first real-world evaluation of PCV13 vaccine effectiveness (VE) against hospitalized vaccine-type community-acquired pneumonia (CAP) in this population. Methods: Using a test-negative design, we identified cases and controls from a population-based surveillance study of adults in Louisville, Kentucky, who were hospitalized with CAP. We analyzed a subset of CAP patients enrolled 1 April 2015 through 30 April 2016 who were aged ≥65 years and consented to have their pneumococcal vaccination history confirmed by health insurance records. Cases were defined as hospitalized CAP patients with PCV13 serotypes identified via culture or serotype-specific urinary antigen detection assay. Remaining CAP patients served as test-negative controls. Results: Of 2034 CAP hospitalizations, we identified PCV13 serotypes in 68 (3.3%) participants (ie, cases), of whom 6 of 68 (8.8%) had a positive blood culture. Cases were less likely to be immunocompromised (29.4% vs 46.4%, P = .02) and overweight or obese (41.2% vs 58.6%, P = .01) compared to controls, but were otherwise similar. Cases were less likely to have received PCV13 than controls (3/68 [4.4%] vs 285/1966 [14.5%]; unadjusted VE, 72.8% [95% confidence interval, 12.8%-91.5%]). No confounding was observed during adjustment for patient characteristics, including immunocompromised status, body mass index, and history of influenza and pneumococcal polysaccharide vaccination (adjusted VE range, 71.1%-73.3%). Conclusions: Our study is the first to demonstrate real-world effectiveness of PCV13 against vaccine-type CAP in adults aged ≥65 years following introduction into a national immunization program.

How can we improve clinical research in pneumonia?

PURPOSE OF REVIEW: The primary challenges in the field of clinical research include a lack of support within existing infrastructure, insufficient number of clinical research training programs and a paucity of qualified mentors. Most medical centers offer infrastructure support for investigators working with industry sponsors or government-funded clinical trials, yet there are a significant amount of clinical studies performed in the field of pneumonia which are observational studies. For this type of research, which is frequently unfunded, support is usually lacking. RECENT FINDINGS: In an attempt to optimize clinical research in pneumonia, at the University of Louisville, we developed a clinical research coordinating center (CRCC). The center manages clinical studies in the field of respiratory infections, with the primary focus being pneumonia. Other activities of the CRCC include the organization of an annual clinical research training course for physicians and other healthcare workers, and the facilitation of international research mentoring by a process of connecting new pneumonia investigators with established clinical investigators. SUMMARY: To improve clinical research in pneumonia, institutions need to have the appropriate infrastructure in place to support investigators in all aspects of the clinical research process.

Adults Hospitalized With Pneumonia in the United States: Incidence, Epidemiology, and Mortality.

BACKGROUND: Understanding the burden of community-acquired pneumonia (CAP) is critical to allocate resources for prevention, management, and research. The objectives of this study were to define incidence, epidemiology, and mortality of adult patients hospitalized with CAP in the city of Louisville, and to estimate burden of CAP in the US adult population. METHODS: This was a prospective population-based cohort study of adult residents in Louisville, Kentucky, from 1 June 2014 to 31 May 2016. Consecutive hospitalized patients with CAP were enrolled at all adult hospitals in Louisville. The annual population-based CAP incidence was calculated. Geospatial epidemiology was used to define ecological associations among CAP and income level, race, and age. Mortality was evaluated during hospitalization and at 30 days, 6 months, and 1 year after hospitalization. RESULTS: During the 2-year study, from a Louisville population of 587499 adults, 186384 hospitalizations occurred. A total of 7449 unique patients hospitalized with CAP were documented. The annual age-adjusted incidence was 649 patients hospitalized with CAP per 100000 adults (95% confidence interval, 628.2-669.8), corresponding to 1591825 annual adult CAP hospitalizations in the United States. Clusters of CAP cases were found in areas with low-income and black/African American populations. Mortality during hospitalization was 6.5%, corresponding to 102821 annual deaths in the United States. Mortality at 30 days, 6 months, and 1 year was 13.0%, 23.4%, and 30.6%, respectively. CONCLUSIONS: The estimated US burden of CAP is substantial, with >1.5 million unique adults being hospitalized annually, 100000 deaths occurring during hospitalization, and approximately 1 of 3 patients hospitalized with CAP dying within 1 year.

Role of Atypical Pathogens in the Etiology of Community-Acquired Pneumonia.

Atypical pneumonia has been described for over 100 years, but some of the pathogens attributed to it have been identified only in the past decades. The most common pathogens are Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila. The epidemiology and pathophysiology of these three pathogens have been studied since their discovery, and are reviewed herein to provide better insight when evaluating these patients, which hopefully translates into improved care. The incidence of atypical pathogens has been shown to be approximately 22% worldwide, but this probably varies with location. The history and physical exam of a patient with atypical pneumonia reveals how patients share many signs and symptoms with their counterpart patients who have typical pneumonias; therefore, the diagnosis primarily depends on laboratory identification, which is evolving and improving. What started out as simple, but difficult to yield cultures, has progressed to modern molecular-based testing assays. Treatment is missed if an empiric regimen includes only monotherapy with a ß-lactam antimicrobial; so, many country guidelines, including the Infectious Diseases Society of America/American Thoracic Society guidelines for community-acquired pneumonia, recommend using a regimen containing either a macrolide or a fluorinated quinolone. Once an atypical pathogen has been identified, evidence trends toward favoring a quinolone, but more data are needed to confirm. The concept of using combination therapy in severe patients is also explored.

Macrolide Use and Neutrophil Function/Cytokine Levels in Hospitalized Patients with Community-Acquired Pneumonia: A Pilot Study.

PURPOSE: The objective of this study was to measure plasma cytokine levels and blood neutrophil functions as well as clinical outcomes in hospitalized patients with community-acquired pneumonia (CAP) treated with or without macrolide use--a known modulator of inflammatory response. METHODS: Subjects with CAP had peripheral blood analyzed for some neutrophil functions (degranulation of secretory vesicles and specific granules, respiratory burst response and phagocytosis) and ten cytokine levels measured in serum and sputum supernatants. Neutrophil function in healthy volunteers was also measured for reference. Values were measured on the day of enrollment, days 2-4 and 5-7, depending on a patient's length of stay. Early and late clinical outcomes were also evaluated. All values were compared between those treated with or without a macrolide. RESULTS: A total of 40 subjects were in this study; 14 received macrolide treatment, and 26 did not. Neutrophil function in the macrolide group was not significantly different compared to the non-macrolide group. None of the median cytokine levels or IQRs were statistically significant between the groups. However, a trend toward decreased IL-6, IL-8, and IFN-γ levels, and favorable clinical outcomes were present in the macrolide group. CONCLUSIONS: This pilot study showed no statistical difference between cytokine levels or neutrophil activity for CAP patients prescribed a macrolide containing regimen. Considering the trend of lower cytokine levels in the macrolide group when comparing the 5- to 7-day time period with the non-macrolide group, a full study with an appropriate sample size may be warranted.

Comparing posteroanterior with lateral and anteroposterior chest radiography in the initial detection of parapneumonic effusions.

BACKGROUND: It is unclear whether anteroposterior (AP) or posteroanterior with lateral (PA/Lat) chest radiographs are superior in the early detection of clinically relevant parapneumonic effusions (CR-PPEs). The objective of this study was to identify which technique is preferred for detection of PPEs using chest computed tomography (CCT) as a reference standard. METHODS: A secondary analysis of a pneumonia database was conducted to identify patients who received a CCT within 24 hours of presentation and also received AP or PA/Lat chest radiographs within 24 hours of CCT. Sensitivity and specificity were then calculated by comparing the radiographic diagnosis of PPEs of both types of radiographs compared with CCT by using the existing attending radiologist interpretation. Clinical relevance of effusions was determined by CCT effusion measurement of >2.5 cm or presence of loculation. RESULTS: There was a statistically significant difference between the sensitivity of AP (67.3%) and PA/Lat (83.9%) chest radiography for the initial detection of CR-PPE. Of 16 CR-PPEs initially missed by AP radiography, 7 either required drainage initially or developed empyema within 30 days, whereas no complicated PPE or empyema was found in those missed by PA/Lat radiography. CONCLUSIONS: PA/Lat chest radiography should be the initial imaging of choice in pneumonia patients for detection of PPEs because it appears to be statistically superior to AP chest radiography.