Healthcare-associated Pneumonia Risk Factors Research Articles

Risk Factors and outcomes associated with inappropriate empiric broad-spectrum antibiotic use in hospitalized patients with community-acquired pneumonia

Background: Inappropriate broad-spectrum antibiotic use targeting methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa can result in increased adverse events, antibiotic resistance, and Clostridioides difficile infection. In 2019, revised ATS/IDSA community-acquired pneumonia (CAP) guidelines removed healthcare-associated pneumonia (HCAP) as a clinical entity and modified patient factors warranting empiric broad-spectrum antibiotic (BSA) use. As a result, most patients hospitalized with CAP should receive empiric antibiotics targeting standard CAP pathogens. Based on revised guidelines, we evaluated predictors and outcomes associated with inappropriate BSA use among hospitalized patients with CAP. Methods: Between November 2019 and July 2022, trained abstractors collected data on non-ICU adult medical patients admitted with CAP at 67 Michigan hospitals who received either an inappropriate empiric BSA on hospital day 1 or 2 or a standard CAP regimen. Inappropriate empiric BSA use was defined as use of an anti-MRSA or anti-pseudomonal antibiotic in a patient eligible for standard CAP coverage per IDSA guidelines. Patients with immune compromise, moderate or severe chronic obstructive pulmonary disease (COPD), pulmonary complication, or guideline-concordant treatment with BSA were excluded. Data collected included comorbidities, antibiotic use and hospitalizations in the preceding 90 days, cultures in the preceding year, signs or symptoms of pneumonia, hospital characteristics, and 30-day postdischarge patient outcomes. Data were collected through chart review and patient phone calls. Predictors of inappropriate empiric BSA were evaluated using logistic general estimating equation (GEE) models, accounting for hospital-level clustering. We assessed the effect of inappropriate empiric BSA (vs standard CAP therapy) on 30-day patient outcomes using logistic GEE models controlling for predictors associated with the outcome and probability of treatment. Results: Of 8,286 included patients with CAP, 2,215 (26.7%) were empirically treated with inappropriate BSA. The median BSA treatment was 3 days (IQR, 2.5). After adjustments, factors associated with inappropriate empiric BSA treatment included hospitalization or treatment with high-risk antibiotics in preceding 90 days, transfer from a postacute care facility, hemodialysis, support with ≥3 L supplemental oxygen, severe sepsis, leukocytosis, and higher pneumonia severity index (Fig. 1). After adjustments, patients with inappropriate empiric BSA treatment had higher readmissions 30 days after discharge, more transfers to the intensive care unit, more antibiotic-associated adverse events, and longer hospitalizations (Fig. 2). Conclusions: Patients hospitalized with CAP often received inappropriate BSA as empiric coverage, and this inappropriate antibiotic selection was associated with worse patient outcomes. To improve patient outcomes, stewardship efforts should focus on reducing inappropriate BSA use in patients hospitalized for CAP with historic HCAP risk factors or severe CAP without other guideline-directed indications for BSA.Financial support. H.M.S. initiative is underwritten by Blue Cross and Blue Shield of Michigan.Disclosures: None

1298. Validation of Local Pseudomonas aeruginosa Risk Factors in Patients with Community-Onset Bacterial Pneumonia

BackgroundClinical guidelines for community-acquired pneumonia (CAP) encourage validation of local risk factors for multidrug-resistant organisms. This study aimed to validate previously derived, local risk factors for Pseudomonas aeruginosa in patients with community-onset bacterial pneumonia at Prisma Health-Midlands’ hospitals. MethodsIn this retrospective, observational cohort study, adult patients hospitalized with pneumonia MS-DRG codes from January 1, 2017 to March 31, 2020 were randomly screened. Enrolled subjects were admitted to 1 of 3 Prisma Health-Midlands’ hospitals with: diagnosis of pneumonia; receipt of inpatient antibiotics within 48 hours of symptom onset; receipt of over 48 hours of antibiotic therapy; and a causative bacterial pathogen identified via respiratory or blood culture, urinary antigen, or respiratory multiplex PCR panel. Performance of the locally derived score was compared to the Drug Resistance in Pneumonia (DRIP) Score, IDSA 2019 CAP guideline risk factors, and healthcare-associated pneumonia (HCAP) risk factors. Endpoints included sensitivity, specificity, positive and negative predictive value, overall accuracy, and over- and undertreatment rates. Overall accuracy was defined as a case in which the gram-negative antibiotic coverage recommended by the scoring schema would have been appropriate for the identified organism, i.e. neither overtreatment (overly broad-spectrum) nor undertreatment (inadequate spectrum). ResultsOf 713 patients screened, 36 patients met criteria and were enrolled. The most common bacterial pathogens identified were Pseudomonas aeruginosa (n = 10, 27.8%) and Streptococcus pneumoniae (n = 10, 27.8%). Performance characteristics for each scoring schema are summarized in Table 1.Table 1. Performance characteristics of risk scores predicting for Pseudomonas aeruginosa community-onset bacterial pneumonia. MDRO=multidrug-resistant organism; DRIP=Drug Resistance in Pneumonia Score; IDSA=Infectious Diseases Society of America 2019 Community-Acquired Pneumonia Guideline risk factors ; HCAP=healthcare-associated pneumonia risk factorsConclusionCompared to DRIP or IDSA 2019 CAP risk scores, the local risk score performed well at ruling out resistant gram-negatives given its higher specificity and lower overtreatment rate; yet, it did not perform as well at ruling in resistant gram-negatives given a lower sensitivity and undertreatment rate. All scores performed better than HCAP risk factors. Data from this study will be utilized to further refine the local risk score algorithm. Disclosures P. Brandon Bookstaver, Pharm D, ALK Abello, Inc. (Grant/Research Support, Advisor or Review Panel member)Biomerieux (Speaker’s Bureau)Kedrion Biopharma (Grant/Research Support, Advisor or Review Panel member) Hana Winders, PharmD, BCIDP, biomerieux (Grant/Research Support) Julie Ann Justo, PharmD, MS, BCPS-AQ ID, bioMerieux (Speaker’s Bureau)Merck & Co. (Advisor or Review Panel member)Therapeutic Research Center (Speaker’s Bureau)Vaxart (Shareholder)

1185. Impact of Utilizing Drug Resistance in Pneumonia (DRIP) Score on Management of Pneumonia

BackgroundPneumonia is a leading cause of infection-related admissions and death. It is imperative that appropriate antibiotic therapy is selected. Traditional scoring systems for identifying at-risk persons for drug-resistant pathogens– i.e., Healthcare-associated pneumonia (HCAP), have been inaccurate and often lead to inappropriate antibiotic selection. A novel pneumonia scoring system –“Drug Resistance in Pneumonia (DRIP)” was implemented at the Detroit Medical Center (DMC) in January 2018. The objective of this study was to evaluate the effectiveness of the DRIP score in reducing the use of broad-spectrum antibiotics and the impact on key outcomes in patients treated for pneumonia.MethodsA retrospective chart review of 89 patients admitted to the DMC for treatment of pneumonia was conducted—45 patients prior to and 44 patients post-implementation of the DRIP score. Basic demographics, signs and symptoms, antibiotics data, pneumonia severity score (CURB – 65), Charlson co-morbidity score, and outcome measures were compared. DRIP scores and HCAP risk factors were calculated for all patients. The definitions of broad-spectrum antibiotics (BSA) were consistent with DMC guidelines for the treatment of pneumonia (antibiotics targeting nosocomial Gram-negative organisms and/or methicillin-resistant Staphylococcus aureus).ResultsDemographics are shown in Table 1. 18 (40%) of the pre-implementation cohort had risk factors for resistance (HCAP risk factors) compared with 14 (32%) in the post. Conversely, 15 (33%) of the pre-implementation cohort had risk factors for resistance (DRIP ≥4) compared with 8 (18%) in the post-implementation period (Table 2). A difference in BSA prescribing was seen in patients previously characterized as having a high risk of resistance (HCAP) but with DRIP score <4 [5/7 (72%) vs.1/7 (16%) (Table 2)]. BSA use was 24 (53%) in the pre-implementation cohort and 12 (27%) in post-implementation cohort, P = 0.03. Durations of antibiotics were 8.3 days vs. 9.8 days respectively, P = 0.04. Readmission with pneumonia at 30 days was 3 (7.5%) for both groups.ConclusionThe implementation of a novel DRIP scoring system resulted in improved prescribing patterns and a significant reduction of broad-spectrum antibiotics by 26% as compared with traditional HCAP score. Disclosures All authors: No reported disclosures.

Treatment Trends and Outcomes in Healthcare-Associated Pneumonia.

The American Thoracic Society and Infectious Diseases Society of America guidelines for management of healthcare-associated pneumonia (HCAP), first published in 2005, have been controversial regarding the selection of empiric broad-spectrum antibiotics, whether the criteria for HCAP predicts the likelihood of infection with multidrug resistant organisms, and whether HCAP patients have improved outcomes when treated with empiric broad-spectrum antibiotics. A retrospective cohort study at 488 US hospitals from July 2007 to November 2011. Patients who met criteria for HCAP were included. Guideline-concordant antibiotics were assessed based on guideline recommendations. We assessed changes in hospital rates of concordant antibiotic use over time and their correlation with outcomes. Among 149,963 patients with HCAP, 19.6% received fully guideline-concordant antibiotics, 21.7% received partially concordant antibiotics, and 58.9% received discordant antibiotics. Guideline concordance increased over time. Rates of fully or partially concordant antibiotics varied across hospitals (median 36.4%; interquartile range 25.8%-49.1%). Among patients who received discordant antibiotics, 81.5% were treated according to community-acquired pneumonia (CAP) guidelines. On average, the rate of guideline concordance increased by 2.2% per 6-month interval, while hospital level rates of mortality, excess length of stay, and progression to respiratory failure did not change. In this large, nationally representative cohort, only 1 in 5 patients with risk factors for HCAP received treatment that was fully in accordance with guidelines, and many received CAP therapy instead. At the hospital level, increases in the use of concordant antibiotics were not associated with declines in mortality, excess length of stay, or progression to respiratory failure.

Antibiotic Prescribing for Adults Hospitalized in the Etiology of Pneumonia in the Community Study.

Community-acquired pneumonia (CAP) 2007 guidelines from the Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) recommend a respiratory fluoroquinolone or beta-lactam plus macrolide as first-line antibiotics for adults hospitalized with CAP. Few studies have assessed guideline-concordant antibiotic use for patients hospitalized with CAP after the 2007 IDSA/ATS guidelines. We examine antibiotics prescribed and associated factors in adults hospitalized with CAP. From January 2010 to June 2012, adults hospitalized with clinical and radiographic CAP were enrolled in a prospective Etiology of Pneumonia in the Community study across 5 US hospitals. Patients were interviewed using a standardized questionnaire, and medical charts were reviewed. Antibiotics prescribed were classified according to defined nonrecommended CAP antibiotics. We assessed factors associated with nonrecommended CAP antibiotics using logistic regression. Among enrollees, 1843 of 1874 (98%) ward and 440 of 446 (99%) ICU patients received ≥1 antibiotic ≤24 hours after admission. Ward patients were prescribed a respiratory fluoroquinolone alone (n = 613; 33%), or beta-lactam plus macrolide (n = 365; 19%), beta-lactam alone (n = 240; 13%), among other antibiotics, including vancomycin (n = 235; 13%) or piperacillin/tazobactam (n = 157; 8%) ≤24 hours after admission. Ward patients with known risk for healthcare-associated pneumonia (HCAP), recent outpatient antibiotic use, and in-hospital antibiotic use <6 hours after admission were significantly more likely to receive nonrecommended CAP antibiotics. Although more than half of ward patients received antibiotics concordant with IDSA/ATS guidelines, a number received nonrecommended CAP antibiotics, including vancomycin and piperacillin/tazobactam; risk factors for HCAP, recent outpatient antibiotic, and rapid inpatient antibiotic use contributed to this. This hypothesis-generating descriptive epidemiology analysis could help inform antibiotic stewardship efforts, reinforces the need to harmonize guidelines for CAP and HCAP, and highlights the need for improved diagnostics to better equip clinicians.

Pneumococcal urinary antigen test use in diagnosis and treatment of pneumonia in seven Utah hospitals.

The pneumocococcal urine antigen test increases specific microbiological diagnosis over conventional culture methods in pneumonia patients. Data are limited regarding its yield and effect on antibiotic prescribing among patients with community-onset pneumonia in clinical practice.We performed a secondary analysis of 2837 emergency department patients admitted to seven Utah hospitals over 2 years with international diagnostic codes version 9 codes and radiographic evidence of pneumonia.Mean age was 64.2 years, 47.2% were male and all-cause 30-day mortality was 9.6%. Urinary antigen testing was performed in 1110 (39%) patients yielding 134 (12%) positives. Intensive care unit patients were more likely to undergo testing, and have a positive result (15% versus 8.8% for ward patients; p<0.01). Patients with risk factors for healthcare-associated pneumonia had fewer urinary antigen tests performed, but 8.4% were positive. Physicians changed to targeted antibiotic therapy in 20 (15%) patients, de-escalated antibiotic therapy in 76 patients (57%). In 38 (28%) patients, antibiotics were not changed. Only one patient changed to targeted therapy suffered clinical relapse. Length of stay and mortality were lower in patients receiving targeted therapy.Pneumococcal urinary antigen testing is an inexpensive, noninvasive test that favourably influenced antibiotic prescribing in a “real world”, multi-hospital observational study.

Development and validation of a clinical risk score for predicting drug‐resistant bacterial pneumonia in older Chinese patients

Health care-associated pneumonia (HCAP) and drug-resistant bacterial pneumonia may not share identical risk factors. We have shown that bronchiectasis, recent hospitalization and severe pneumonia (confusion, blood urea level, respiratory rate, low blood pressure and 65 year old (CURB-65) score ≥ 3) were independent predictors of pneumonia caused by potentially drug-resistant (PDR) pathogens. This study aimed to develop and validate a clinical risk score for predicting drug-resistant bacterial pneumonia in older patients. We derived a risk score by assigning a weighting to each of these risk factors as follows: 14, bronchiectasis; 5, recent hospitalization; 2, severe pneumonia. A 0.5 point was defined for the presence of other risk factors for HCAP. We compared the areas under the receiver-operating characteristics curve (AUROC) of our risk score and the HCAP definition in predicting PDR pathogens in two cohorts of older patients hospitalized with non-nosocomial pneumonia. The derivation and validation cohorts consisted of 354 and 96 patients with bacterial pneumonia, respectively. PDR pathogens were isolated in 48 and 21 patients in the derivation and validation cohorts, respectively. The AUROCs of our risk score and the HCAP definition were 0.751 and 0.650, respectively, in the derivation cohort, and were 0.782 and 0.671, respectively, in the validation cohort. The differences between our risk score and the HCAP definition reached statistical significance. A score ≥ 2.5 had the best balance between sensitivity and specificity. Our risk score outperformed the HCAP definition to predict pneumonia caused by PDR pathogens. A history of bronchiectasis or recent hospitalization is the major indication of starting empirical broad-spectrum antibiotics.

Year in review 2013: Lung cancer, respiratory infections, tuberculosis, cystic fibrosis, pleural diseases, bronchoscopic intervention and imaging

This Year in Review examines the most relevant articles published on lung cancer, respiratory infections, tuberculosis (TB), cystic fibrosis (CF), pleural diseases, and interventional pulmonology and imaging in Respirology and other respiratory medicine journals during 2013. Important findings are highlighted with comments in the following sections, each of which was contributed by an author as named in the beginning of each section.

Healthcare-Associated Pneumonia among Hospitalized Patients: Is It Different from Community Acquired Pneumonia?

BackgroundThe increasing number of outpatients with multidrug-resistant (MDR) pathogens has led to a new category of pneumonia, termed healthcare-associated pneumonia (HCAP). We determined the differences in etiology and outcomes between patients with HCAP and those with community-acquired pneumonia (CAP) to clarify the risk factors for HCAP mortality.MethodsA retrospective study comparing patients with HCAP and CAP at Jeju National University Hospital. The primary outcome was 30-day mortality.ResultsA total of 483 patients (208 patients HCAP, 275 patients with CAP) were evaluated. Patients with HCAP were older than those with CAP (median, 74 years; interquartile range [IQR], 65-81 vs. median, 69 years; IQR, 52-78; p<0.0001). Streptococcus pneumoniae was the major pathogen in both groups, and MDR pathogens were isolated more frequently from patients with HCAP than with CAP (18.8% vs. 4.9%, p<0.0001). Initial pneumonia severity was greater in patients with HCAP than with CAP. The total 30-day mortality rate was 9.9% and was higher in patients with HCAP based on univariate analysis (16.3% vs. 5.1%; odds ratio (OR), 3.64; 95% confidence interval (CI), 1.90-6.99; p<0.0001). After adjusting for age, sex, comorbidities, and initial severity, the association between HCAP and 30-day mortality became non-significant (OR, 1.98; 95% CI, 0.94-4.18; p=0.167).ConclusionHCAP was a common cause of hospital admissions and was associated with a high mortality rate. This increased mortality was related primarily to age and initial clinical vital signs, rather than combination antibiotic therapy or type of pneumonia.

Health care‐associated pneumonia in haemodialysis patients: Clinical outcomes in patients treated with narrow versus broad spectrum antibiotic therapy

Although the 2005 American Thoracic Society/Infectious Disease Society of America antibiotic guidelines classify pneumonia occurring in patients receiving chronic haemodialysis as health care-associated pneumonia (HCAP), and thus recommend treatment with broad-spectrum antibiotics for these patients, little data support this classification. We compared clinical outcomes in haemodialysis patients hospitalized with pneumonia, who were treated with broad-spectrum antibiotics versus narrow-spectrum antibiotics. One hundred twenty-five haemodialysis patients with pneumonia met eligibility criteria. Categorization into the community-acquired pneumonia (CAP) group or HCAP group was based on antibiotic therapy patients received. Time to oral therapy, time to clinical stability, length of stay and mortality were compared. CAP and HCAP patients did not differ in Pneumonia Severity Index and Charlson Comorbidity index scores, but HCAP patients were more likely to meet criteria for severe pneumonia. Patients treated with HCAP therapy had a significantly longer time to oral therapy than CAP patients (9.2 vs 3.2 days, P < 0.001) and a significantly longer length of stay (11.9 vs 5.1 days, P < 0.001). Time to clinical stability was marginally longer in the HCAP group (3.1 vs 2.4 days, P = 0.07). Patients treated with HCAP therapy had longer continuation of intravenous antibiotics after reaching clinical stability (5.5 vs 0.78 days, P < 0.001). This study is the first to our knowledge to describe clinical outcomes in patients with haemodialysis as their only HCAP risk factor. Narrow-spectrum antibiotics may be safe in haemodialysis patients with no other HCAP risk factors. HCAP therapy delayed de-escalation to oral antibiotics was associated with increased duration of intravenous antibiotics and length of stay.

Poor prediction of potentially drug-resistant pathogens using current criteria of health care-associated pneumonia

Health care-associated pneumonia (HCAP) includes a broad range of patients having frequent or chronic contact with health care systems. However, the relationship between current defining criteria for HCAP and the risk of potentially drug-resistant (PDR) pathogens is controversial. We retrospectively evaluated patients admitted to Severance Hospital in South Korea with culture-positive pneumonia from January 2008 to December 2009. We analyzed the associations between risk factors for HCAP and infection with PDR pathogens, and developed a new scoring system to predict infection with PDR pathogens. Among 339 patients, PDR pathogens were observed in 122 (36.0%). PDR pathogens were more common in HCAP than community-acquired pneumonia (CAP) (48.5% versus 23.8%, P<0.001). In a logistic regression, prior hospitalization within 90 days of pneumonia (OR=2.51, P=0.003), recent treatment with antimicrobials (OR=2.35, P=0.039), and nasogastric tube feeding (OR=15.28, P<0.001) were independently associated with PDR pathogens. For the prediction of PDR pathogens, the sensitivity and specificity of current HCAP criteria were 66.4% and 60.4%, respectively, and 68.0% and 67.3%, respectively, for the new scoring system. Moreover, the new scoring system showed better diagnostic accuracy than current HCAP criteria (area under curve=0.711 versus 0.634, P<0.001). The current HCAP criteria are poor predictors of PDR pathogens and all patients with HCAP should not be empirically treated for these pathogens. To avoid excessive antibiotic use, individual risk stratification approaches should be considered.

Guideline-concordant therapy and outcomes in healthcare-associated pneumonia

Healthcare-associated pneumonia (HCAP) guidelines were first proposed in 2005 but have not yet been validated. The objective of this study was to compare 30-day mortality in HCAP patients treated with either guideline-concordant (GC)-HCAP therapy or GC community-acquired pneumonia (CAP) therapy. We performed a population-based cohort study of >150 hospitals in the US Veterans Health Administration. Patients were included if they had one or more HCAP risk factors and received antibiotic therapy within 48 h of admission. Critically ill patients were excluded. Independent risk factors for 30-day mortality were determined in a generalised linear mixed-effect model, with admitting hospital as a random effect. Propensity scores for the probability of receiving GC-HCAP therapy were calculated and incorporated into a second logistic regression model. A total of 15,071 patients met study criteria and received GC-HCAP therapy (8.0%), GC-CAP therapy (75.7%) or non-GC therapy (16.3%). The strongest predictors of 30-day mortality were recent hospital admission (OR 2.49, 95% CI 2.12-2.94) and GC-HCAP therapy (OR 2.18, 95% CI 1.86-2.55). GC-HCAP therapy remained an independent risk factor for 30-day mortality (OR 2.12, 95% CI 1.82-2.48) in the propensity score analysis. In nonsevere HCAP patients, GC-HCAP therapy is not associated with improved survival compared with GC-CAP therapy.

A retrospective study of health care-associated pneumonia patients at Aichi Medical University hospital

Health care-associated pneumonia (HCAP) was defined in the American Thoracic Society/Infectious Disease Society of America guidelines on hospital-acquired pneumonia in 2005. However, little is known about the occurrence of HCAP in Japan. A retrospective review of background characteristics, pathological conditions, causative organisms, initial treatments, and risk factors for HCAP was conducted to determine the relationship of HCAP to community-acquired pneumonia and hospital-acquired pneumonia. Thirty-five patients who were admitted to our hospital for pneumonia acquired outside our hospital were included and were stratified by disease severity according to the Japanese Respiratory Society risk stratification guidelines (A-DROP [age, dehydration, respiratory failure, orientation disturbance, and shock blood pressure] criteria). All patients had an underlying disease. A total of 70 microbial strains (25 gram-positive, 37 gram-negative, 6 anaerobic, and 2 causative of atypical pneumonia) were isolated from sputum cultures, showing high isolation frequencies of Pseudomonas aeruginosa and Staphylococcus aureus and extremely low isolation frequencies of Streptococcus pneumoniae and Haemophilus influenzae. "History of hospitalization within 90days before the onset of pneumonia" was the most common risk factor, and most of the patients had two or three risk factors. Initially, monotherapy [mainly tazobactam/piperacillin (TAZ/PIPC), sulbactam/ampicillin (SBT/ABPC), ceftriaxone (CTRX), cefepime (CPFM), carbapenems, or fluoroquinolones] or combination therapy (beta-lactam and fluoroquinolone) were administered and gave clinical effects in 63% (22/35) of cases. Bacteriological effects were seen in most strains (57%; 40/70). Since the causative organisms of HCAP were closely related to those of hospital-acquired pneumonia and not to community-acquired pneumonia, we believe that aggressive chemotherapy using broad-spectrum antimicrobials is needed in the initial treatment.

1407 Incidence and Risk Factors for Healthcare-Associated Pneumonia in a Pediatric Intensive Care Unit

1407 Incidence and Risk Factors for Healthcare-Associated Pneumonia in a Pediatric Intensive Care Unit

Health-Care-Associated Pneumonia

Health-Care-Associated Pneumonia

What Are the Important Risk Factors for Healthcare-Associated Pneumonia?

Healthcare-associated pneumonia (HCAP) is a category of nosocomial pneumonia defined by the 2005 American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines to include any patient who has been hospitalized in an acute care hospital for 2 or more days within the past 90 days; residents of a nursing home or long-term care facility; recipients of recent intravenous antibiotic therapy, chemotherapy, or wound care within the past 30 days; or patients who have attended a hospital or hemodialysis clinic. In creating this relatively new category the ATS/IDSA acknowledged that these patients are at increased risk for infection with antibiotic-resistant organisms and that initial inadequate antibiotic coverage leads to increased mortality. Risk factors for the development of pneumonia and the development of pneumonia caused by drug-resistant pathogens, primarily methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, are not the same among the subgroups of HCAP (i.e., dialysis patients have different risks than nursing home patients). Furthermore there is significant heterogeneity of risk factors for HCAP within the subgroups due to variations in contextual factors such as local microbiology and methods of health care delivery and variations of individual risk factors such as functional status or prior antibiotic exposure. This review examines the evidence for the creation of the category of HCAP, including the risk factors for drug-resistant pneumonia in each of the subgroups that constitute HCAP. This review demonstrates that the guidelines have effectively targeted a population at greater risk for pneumonia caused by drug-resistant pathogens. However, within the broad range of HCAP infections, there is significant heterogeneity in terms of the magnitude of the risk as well as the type of risk (i.e., risk for MRSA, multidrug-resistant gram-negative bacilli (MDR-GNB), or both).