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Clinical Investigations: INFECTION |

Evaluation of the Winthrop-University Hospital Criteria to Identify Legionella Pneumonia* FREE TO VIEW

Samir K. Gupta, MD; Thomas F. Imperiale, MD; George A. Sarosi, MD, FCCP
Author and Funding Information

*From the Division of Infectious Diseases (Dr. Gupta) and the Division of Gastroenterology (Dr. Imperiale), Indiana University School of Medicine (Dr. Sarosi), Indianapolis, IN.

Correspondence to: Samir K. Gupta, MD, Indiana University School of Medicine, Whishard Hosptial OPW-430, 1001 W 10th St, Indianapolis, IN 46202; e-mail: sgupta1@iupui.edu



Chest. 2001;120(4):1064-1071. doi:10.1378/chest.120.4.1064
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Study objective: To measure the ability of a set of clinical parameters, the Winthrop-University Hospital (WUH) criteria, to identify Legionella pneumonia while discriminating against bacteremic pneumococcal pneumonia at the time of hospitalization for community-acquired pneumonia (CAP).

Design: Retrospective case-control study.

Setting: An urban county hospital and a tertiary-care Veterans Affairs hospital.

Patients: Thirty-seven patients with Legionella pneumonia (diagnosed by a positive result of a urinary Legionella antigen test) and 31 patients with bacteremic pneumococcal pneumonia. A subgroup of patients with all required laboratory criteria were studied further.

Results: The WUH criteria correctly identified 29 of 37 patients with Legionella pneumonia (sensitivity, 78%; 95% confidence interval [CI], 61 to 90%), while successfully excluding legionellosis in 20 of 31 patients with bacteremic pneumococcal pneumonia (specificity, 65%; 95% CI, 45 to 80%). The positive and negative predictive values, adjusted for a relative prevalence of 1:3 between Legionella and Streptococcus pneumoniae bacteremia, were 42% (95% CI, 25 to 61%) and 90% (95% CI, 74 to 97%), respectively. In the subgroup analysis, the WUH criteria were successful in identifying 20 of 23 patients with Legionella pneumonia (sensitivity, 87%; 95% CI, 65 to 97%), while excluding legionellosis in 9 of 18 patients with bacteremic pneumococcal pneumonia (specificity, 50%; 95% CI, 27 to 73%). The adjusted positive and negative predictive values for a 1:3 relative prevalence were 37% (95% CI, 20 to 59%) and 92% (95% CI, 62 to 98%), respectively. The predictive values were changed in the directions expected for an increased relative prevalence of 1:1. The areas under the receiver operating characteristic curves were 0.72 ± 0.06 for the entire study group and 0.68 ± 0.09 for the subgroup.

Conclusions: Although the WUH criteria discriminated fairly well between cases (mean ± SE) and control subjects, the sensitivity is not high enough to exclude legionellosis confidently. These results suggest that empiric therapy for Legionella pneumonia should be included in the initial antibiotic regimen for hospitalized patients with CAP.

Current American Thoracic Society recommendations for the treatment of community-acquired pneumonia (CAP) not requiring intensive-care support advise the empiric use of β-lactam antibiotics, while leaving the decision to treat the patient for Legionella to the individual physician.1Because appropriate antibiotic therapy should be started within hours of presentation,2the decision to treat a patient for Legionella must be made quickly. Because of the low mortality rate associated with untreated cases of legionellosis in their study, Mundy et al3have called into question the routine use of macrolide antibiotics to cover atypical pathogens. However, their conclusion was based on a paucity of cases of Legionella pneumonia diagnosed at their institution. Studies from other institutions within the United States46 and around the world,78 however, suggest that the prevalence for legionellosis is significantly higher, ranging from 3 to 12.2%. Also, bacterial resistance to these antibiotics is emerging as their use increases.911 If legionellosis could be diagnosed or excluded on hospital admission, appropriately specific therapy could be initiated and the emergence of resistance possibly could be slowed. Rapid diagnostic procedures currently available include direct fluorescent antibody (DFA) and urine Legionella antigen testing. The DFA test is not highly sensitive. The urine antigen test, although highly specific, only identifies Legionella pneumophila serogroup 1 and may not yield positive test results for several days after the onset of symptoms.12 Therefore, the diagnosis of Legionella pneumonia at the time of hospital admission by clinical criteria, especially in high-prevalence regions, might affect the timing and choice of appropriate antibiotic therapy and reduce the potentially severe morbidity and mortality associated with this disease.1314

In 1998, Cunha15published a weighted point evaluation scale, the Winthrop-University Hospital (WUH) criteria, to identify legionellosis based on clinical criteria. This comprehensive set of criteria incorporates most clinical symptoms and signs that previously were believed to be associated with legionellosis1620 and arbitrarily assigns points that are weighted more heavily for extrapulmonary manifestations that are thought to be more specific for this etiology of pneumonia. Negative points are given for signs or symptoms classically associated with other pathogens, such as pneumococcus or Mycoplasma. Cunha15 successfully tested this scale with three case reports of legionellosis from the medical literature, but no systematic evaluation has been performed.

We hypothesized that this scale would be neither highly sensitive in diagnosing Legionella pneumonia nor satisfactorily discriminatory against another lethal etiology of CAP, Streptococcus pneumoniae. Legionellosis is common in our patient population and may be comparable in presentation to pneumococcal pneumonia.7,2125 Therefore, we attempted to evaluate the utility of these clinical criteria to identify Legionella pneumonia at the time of hospital admission for CAP by performing a retrospective case-control study between groups of hospitalized patients known definitively to have either Legionella or pneumococcal pneumonia.

Patient Population

The patients in this study were hospitalized either at the Indianapolis Roudebush Veterans Hospital (a tertiary-care referral center for Indiana, eastern Illinois, and western Ohio) or the Wishard Memorial Hospital (a county hospital serving the residents of Marion County, which includes Indianapolis). Both are large tertiary-care academic facilities that primarily serve underinsured or noninsured patients.

Inclusion and Exclusion Criteria

Patients admitted to the hospital between January 1994 and November 1999 were screened for inclusion in the study by examining the laboratory records for positive results of urine Legionella antigen tests and for blood cultures positive for S pneumoniae. All patients included in the study had initial clinical presentations and chest radiograph findings that were consistent with CAP. Patients with positive results of urine Legionella antigen tests but no evidence of coinfection were included in the Legionella case group. The control group with pneumococcal pneumonia consisted of patients with at least two serial blood cultures that were positive for S pneumoniae but negative for the urinary Legionella antigen. Patients were excluded from the study if there was any evidence of coinfection (ie, by sputum Gram’s stain, culture, or serology) for any other pathogen. Patients also were excluded from the study if their clinical history either was unavailable or incompatible with acute CAP.

Scoring System, Variables Studied, and Definitions

The WUH point scoring scale is shown in Table 1 with three hypothetical examples of its use. A score of < 5 makes legionellosis unlikely, a score from 5 to 9 makes the diagnosis probable, and a score of ≥ 10 makes legionellosis highly probable. These cutoffs were arbitrarily chosen by Cunha.15 Data were considered abnormal if the values were outside the range of normal for the particular assay used for each hospital at the time of hospital admission (B. Cunha, MD; personal communication; December 1, 1999). According to Cunha, any otherwise unexplained abnormality of laboratory values from the time of hospital admission through the first 7 days of hospitalization (ie, as the disease progresses and becomes more apparent) may be used to fulfill the WUH criteria. Relative bradycardia (ie, an inappropriately low heart rate for the elevation of temperature) has been defined previously.,15 Increases in serum creatinine, bilirubin, or transaminase levels or decreases in serum sodium or phosphorus levels were considered to be positive results by Cunha only if they were transient, as opposed to persistently abnormal despite appropriate treatment. This would prevent the inclusion of patients with non-Legionella causes of these abnormalities. Microscopic hematuria was defined as more than two RBCs per high-power field.

If data were not available for a particular criterion, they were assumed to be normal, and no score was assigned. Aspartate aminotransferase levels were used (as opposed to alanine aminotransferase levels or a combination of the two) because aspartate aminotransferase data were more frequently available. Since all patients did not have a comprehensive laboratory evaluation, proportions were not based on the total sample sizes, but, rather, on the number of data points available. A subset analysis was subsequently performed on patients with all required laboratory data.

In addition to the information required for the WUH scale, other data collected for each patient included gender, length of hospital stay (ie, the number of days from hospital admission to discharge or death), initial leukocyte count, requirement for ventilatory assistance (either invasive or noninvasive), and mortality. Underlying comorbidities, including HIV status, also were recorded.

Laboratory Analysis

All Legionella antigen testing for both hospitals was performed in one centralized laboratory. Before March 25, 1996, specimens underwent a procedure incorporating a direct, sandwich-type, solid-phase radioimmunoassay using radioactive iodine labeling.26 Since then, Legionella antigen testing has been performed by horseradish peroxidase-labeled enzyme-linked immunosorbent assay. The two methods are equivalent in performance specifications (J. Smith-Davis, R. Kohler, MD; personal communication; January 12, 2000). Specimens for blood cultures were obtained and observed for growth using standard laboratory methods.

Statistical Analysis

All data were analyzed using computer software (Statistical Analysis System; SAS Institute; Cary, NC). The Student’s t test was used to compare the continuous baseline characteristics of the cohorts (ie, age, total leukocyte count, and length of stay) and the WUH scores obtained at hospital admission and through the first week of hospitalization. Fisher’s Exact Test orχ 2 test was used to compare the groups’ binary clinical characteristics and the proportions of patients that scored in the highly probable category. All significance testing was two-sided. A p value of < 0.05 was considered to be statistically significant. Comparisons between the two groups’ actual laboratory values were not documented, as only the presence of a laboratory abnormality (and not the degree of the abnormality) was required. Sensitivities and specificities were derived for the WUH scale, defining scores in the highly probable category as positive; scores in the other two categories were classified as negative. Ninety-five percent confidence intervals (CIs) were derived for sensitivities, specificities, and predictive values of the WUH scale. The receiver operating characteristic (ROC) curve area was measured as an index of discrimination between pneumococcal and Legionella cohorts.

Because this study only considered pneumonias caused by Legionella and S pneumoniae, relative prevalences between these two pathogens, as determined from US epidemiologic studies of CAP,46 were used to adjust the calculated predictive values. These studies, the patient populations in which were similar to that in our study in that they did not exclude patients because of disease severity and that they utilized the urine Legionella antigen assay in their hospital admission diagnostic panel, have shown that the relative ratios of Legionella to S pneumoniae as the cause of CAP range from 1:3 to 1:1. We subsequently used prevalence estimates of 25% and 50% for Legionella, when considering only populations consisting of these two etiologies of CAP in calculating the ranges of possible, adjusted predictive values.

Forty patients had Legionella pneumonia but no evidence of pneumococcal infection. Two patients subsequently were excluded for coinfections (one for Klebsiella pneumoniae in the sputum and the other for a K. pneumoniae urinary tract infection). Another patient was excluded because no hospital admission history and physical examination were found. Thus, 37 patients remained eligible for study in the Legionella group. All patients with S pneumoniae in blood cultures and with chest radiographs and clinical presentations that were consistent with CAP (32 patients in all) were screened for inclusion in the pneumococcal control group. All were found to have at least two blood cultures that were positive for this pathogen but immunoassays that were negative for the urine Legionella antigen. One patient was excluded because of concomitant Enterobacter bacteremia. The remaining 31 patients comprised the pneumococcus group.

Baseline Characteristics

The baseline characteristics seen in Table 2 were comparable between the two groups. There were more men than women in both groups, primarily due to the inclusion of patients from the Veterans Affairs hospital. The only statistical difference between the groups was the greater proportion of patients who were HIV-positive in the pneumococcus group than in the Legionella group (19% vs 2.7%, respectively; p = 0.04). Ventilatory assistance and mortality were higher in the pneumococcus group, but the differences were not statistically significant. Due to the small number of end points, no correlation analysis between WUH score and ventilatory assistance or mortality could be performed. These three characteristics of the two groups (ie, HIV positivity, ventilatory assistance, and mortality) were similar to those seen in other studies.46,2732

Main Analysis

Lethargy was significantly more common in the Legionella group on hospital admission (43% vs 3.2%, respectively; p < 0.001), whereas pleuritic chest pain was more common in the pneumococcus group (61% vs 16%, respectively; p < 0.001). As expected, nonresponse toβ -lactam therapy alone was seen only in the Legionella group. The proportions of patients with electrolyte or renal abnormalities (eg, hyponatremia, hypophosphatemia, increased creatinine, or microscopic hematuria) were greater in the Legionella cohort, although only hematuria reached statistical significance (p = 0.03). These findings did not change appreciably when data gathered through the first 7 days after hospital admission were analyzed (data not shown). It should be noted that titers for cold agglutinins (used as an indicator for Mycoplasma pneumonia) were not drawn on any patient. A subgroup analysis for patients with complete data follows (vide infra).

Table 3 summarizes the results applying the WUH scale to the 37 and 31 patients, respectively, with either Legionella or pneumococcal pneumonia. For the Legionella group, the mean hospital admission score of 14.6 was significantly higher than the corresponding score of 7.5 for the S pneumoniae group (p < 0.001). More patients in the Legionella group scored in the highly probable category (29 of 37 patients; 78%) on hospital admission compared to the pneumococcal group (11 of 31 patients; 35%; p < 0.001). These differences persisted through the first week after hospital admission (data not shown).

If the category of “highly probable” is defined as “positive for the diagnosis of legionellosis,” sensitivity for the WUH criteria is 78% (95% CI, 61 to 90%) and specificity is 65% (95% CI, 45 to 80%). The positive predictive value is 73% (95% CI, 56 to 85%), while the negative predictive value is 71% (95% CI, 51 to 86%). Following adjustment for a prevalence of 25% for Legionella, the positive predictive value fell to 42% (95% CI, 25 to 61%) and the negative predictive value increased to 90% (95% CI, 74 to 97%). For a prevalence of 50% for Legionella, the positive and negative predictive values become 69% (95% CI, 54 to 84%) and 75% (95% CI, 54 to 87%), respectively. The mean (±SE) ROC curve area of 0.72 ± 0.06 is consistent with a moderate degree of discrimination of the WUH clinical criteria between the two causes of CAP.

Subgroup Analysis

All patients in the subgroup analysis had complete laboratory data available, including those for the major extrapulmonary criteria to support the diagnosis of legionellosis (ie, serum sodium, phosphorus, aminotransferase, bilirubin, and creatinine levels and urinalysis results) by the WUH criteria. The most common reason for failure to meet the full criteria was the lack of data on serum phosphorus levels. This occurred primarily after June 1998 when phosphorus level was no longer part of the standardized comprehensive metabolic panel. Twenty-three patients in the Legionella group and 18 patients in the pneumococcus group remained for analysis. The clinical characteristics of this subgroup were no different than those of the overall study group. Lethargy (48% vs 0%, respectively; p < 0.001) and pleuritic chest pain (61% vs 17%, respectively; p < 0.01) were significantly more common in the Legionella and pneumococcus groups, respectively. The trends observed in the main analysis for extrapulmonary manifestations and in electrolytic, renal, and hepatobiliary laboratory tests were present in the subgroup analysis. No differences in laboratory criteria were statistically significant, except for the presence of microscopic hematuria seen in the Legionella group compared with that in the pneumococcus group (61% vs 22%, respectively; p = 0.03).

Table 4 shows the WUH scores at hospital admission for those patients with complete laboratory data. As before, there was a significantly greater proportion of patients in the Legionella subgroup (20 of 23 patients; 87%) than in the pneumococcus group (9 of 18 patients; 50%) who scored in the highly probable category on hospital admission (p = 0.02). The three patients in the Legionella subgroup who did not qualify for the highly probable category all had elevated transaminase levels, but none fulfilled any of the criteria on the 5-point list of criteria (ie, abdominal pain with or without diarrhea, acute renal failure, relative bradycardia, and no response to β-lactam therapy). These three patients had WUH scores at hospital admission of 3, 3, and 9. The other 20 patients had at least one of the criteria on the 5-point list. Hospital admission sensitivity in this subgroup analysis was 87% (95% CI, 65 to 97%), and specificity was 50% (95% CI, 27 to 73%). The positive predictive value of 69% (95% CI, 49 to 84%) decreased to 37% (95% CI, 20 to 59%) when adjusted for a 25% prevalence of Legionella, and the negative predictive value subsequently increased from 75% (95% CI, 43 to 93%) to 92% (95% CI, 62 to 98%). Using a 50% prevalence for Legionella, the positive and negative predictive values became 64% (95% CI, 44 to 81%) and 79% (95% CI, 46 to 94%), respectively. The ROC curve area of 0.68 ± 0.09 in this subgroup is similar in magnitude to that found in the main analysis.

Legionella is a leading cause of CAP, especially in those patients requiring hospitalization.46,2729,33 The difficulty lies in making a timely diagnosis with subsequent decisions about therapy. Many physicians treat less severe cases of CAP only withβ -lactam antibiotics, which are ineffective against Legionella. In this study, 11 of the 37 patients in the Legionella group, some of whom were hospitalized as recently as 1999, were started on a regimen ofβ -lactam therapy alone. Only when a positive result for the urine antigen test was received did appropriate anti-Legionella therapy begin. However, there is a growing fear that the widespread use of the newer-generation macrolides and fluoroquinolones may result in bacterial resistance to these drugs. A highly sensitive, specific, and rapid screening test for legionellosis at the time of hospital admission is desirable. DFA and urine antigen testing are both rapid tests. However, the former is insensitive and depends on the expertise of the laboratory, whereas the latter has so far been proven useful only for the detection of L pneumophila serogroup 1 and its results may become positive only several days after the onset of symptoms.,12,34 Therefore, clinical criteria that would identify all cases of legionellosis and would discriminate Legionella pneumonia from other causes on hospital admission might be useful for directing the choice of the initial antibiotic therapy.

Olaechea et al35designed a clinical prediction rule to distinguish atypical from typical etiologies of CAP, but this rule was derived from and designed only for patients requiring intensive care. These patients should automatically receive treatment for Legionella according to current guidelines. Keller and colleagues36 have derived a clinical predictive model for distinguishing patients with Legionnaires disease as the cause of CAP requiring hospitalization; however, neither the model nor confirmatory studies have yet been published. As far as we know, the WUH scale is the only published set of clinical criteria for identifying legionellosis requiring hospitalization that is not limited to intensive care. The criteria seen in Table 1 are primarily based on the initial observational studies of Legionella pneumonia from the late 1970s,1618,30,3738 and permit the WUH scale to be fairly comprehensive. All of these criteria were examined in this study. Some clinical findings were significantly more common in the Legionella group, whereas others were equally prevalent in both groups.

The comparisons of WUH scores should not be affected by confounding baseline characteristics, as the two groups were similar in age, gender, and most comorbid conditions. The only significant difference between the two groups was the larger proportion of HIV-infected patients in the pneumococcus group. However, this should not affect the clinical criteria scores in the pneumococcus group as the presence of HIV infection does not typically affect the presentation or severity of bacteremic pneumococcal pneumonia.39

We tested the ability of these clinical criteria to discriminate between Legionella and pneumococcal pneumonia. The testing modalities of urinary antigen testing for Legionella and bacteremia with pneumococcus were chosen because of their clinical practicality, specificity, reproducibility, and established use in definitively identifying the etiology for CAP on hospital admission.6,2829,34 Requiring positive sputum cultures or serologic tests for the diagnosis of Legionella pneumonia is impractical and insensitive. The utility of positive sputum cultures for pneumococcal pneumonia is debated due to questionable specificity. Since all patients in the pneumococcus group had negative results of Legionella antigen tests, legionellosis was considered in the initial differential diagnosis, making the comparison between the two groups using the WUH scale more valid clinically.

The WUH system was applied in this study at the time of hospital admission. Cunha15 also uses this scale with data gathered through the first 7 days of hospitalization, but this would not be practical as a screening modality at the onset of hospitalization. We examined the records of the study patients gathered through the first week (data not shown), but this information did not appreciably affect the comparison between the two groups.

Because prior experience has shown that it is difficult to distinguish Legionnaires disease from other pneumonia syndromes,7,2125 we hypothesized that the WUH system would not prove useful as a screening or discriminatory test for legionellosis at hospital admission for pneumonia. Contrary to our hypothesis, the sensitivities on hospital admission for the WUH system were higher than anticipated at 78% and 87%, respectively, for the main analysis and subgroup analysis. These are comparable to that of the urinary antigen test for L pneumophila serogroup 1. However, the specificities on hospital admission were just 65% and 50%, respectively, for the main cohort and the subgroup. The positive predictive values on hospital admission were low, ranging from 37 to 64% for the subgroup population, whereas the negative predictive values ranged from 79 to 92%. The predictive values changed in the expected directions for a range of relative prevalences between Legionella and S pneumoniae bacteremia. However, the predictive values of the WUH criteria still do not reliably and accurately discriminate between the two pathogens, even for a relative prevalence of 50%. Although the sensitivity of the WUH system was higher than initially suspected, the false-negative rates would be 22% and 13% for the main analysis and subgroup analysis, respectively. Considering the potential lethality of Legionella pneumonia, the inability to identify and subsequently treat 13 to 22% of patients with this disease is clinically unacceptable. Therefore, the sensitivity of the WUH system is not high enough to allow the withholding of antibiotics for legionellosis empirically when the prediction rule indicates that Legionella is not highly probable.

The ROC curve areas were only fair to moderate for discrimination between the two groups. Thus, the WUH scale cannot be used clinically to distinguish Legionella from bacteremic pneumococcal pneumonia. It should be remembered that these performance characteristics were based on the inclusion of only two causes of CAP (albeit two of the more morbid and fatal causes) and that the Legionella patients in the study were restricted to those infected with L pneumophila serogroup 1. When applying the WUH criteria to all patients with CAP regardless of the etiologic pathogen, the sensitivity and negative predictive value may decrease further while the specificity and positive predictive value may improve. Therefore, a more refined set of clinical criteria, based only on the more discriminatory parameters found in this study along with other relevant clinical variables, may prove useful. If a rule can be developed with sensitivity higher than the WUH scale, then anti-Legionella therapy could be safely withheld in those patients with low scores. The number of cases with low scores would likely increase if consecutive cases of CAP were then prospectively studied.

A strength of the study is the strict inclusion criteria, as there were no confounding criteria between the two analyzed etiologies of pneumonia, Legionella and S pneumoniae. The study, though, has several limitations. One limitation is the sampling strategy for the study groups. It would have been preferable to test the WUH system on a cohort of consecutive patients with CAP who required hospitalization, all of whom would have undergone extensive diagnostic testing for a specific etiology. However, this methodology was neither feasible nor practical. Thus, we performed a retrospective case-control study and adjusted the test characteristics for the literature-based relative prevalence of Legionella and pneumococcus. However, as the study group is not a consecutive cohort, both cases (patients) and control subjects may be biased with respect to the spectrum of disease in that those patients selected for specific microbiological diagnostic testing may have had more classic manifestations. This type of bias might overestimate the performance of the WUH system.

A second important limitation is the small sample size. Although all patients at two large academic hospitals who received diagnoses of pneumonia were screened over a period of 6 years, a total of only 68 patients (Legionella group, 37 patients; pneumococcus group, 31 patients) met the inclusion criteria. This is explained by the fact that most patients with pneumonia did not have Legionella testing performed, although it was readily available. Also, because of the usually rapid positive culture results for pneumococcal bacteremia, it was not clinically imperative to test for Legionella. A large number of patients never had Legionella tests performed, even in the face of negative blood test and sputum culture results. This most likely was due to a lack of clinical suspicion for legionellosis. Another possibility is that the initial antimicrobial therapy may have included quinolones or macrolides. These agents would treat Legionella empirically and would reduce the need for a precise microbiological diagnosis. Conversely, urine antigen testing was probably pursued more often in those patients who had clinical features that were more classically consistent with Legionella. If this were the case, then the resulting incorporation bias would tend to make the WUH criteria appear better than they truly were. Also, a significant proportion of the overall group of patients did not have full laboratory data available, primarily due to the lack of data on serum phosphorus levels after June 1998. This further limited the number of patients for whom complete data were available. One other possible limitation of this study was the WUH system itself. Any laboratory data outside the range of normal could fulfill diagnostic criteria; the degree of the abnormality was not important.

In summary, the WUH criteria are not adequately sensitive to warrant general use as a type of prediction rule for diagnosing legionellosis on hospital admission. Therefore, it should be assumed that Legionella might be the cause of CAP, and empiric anti-Legionella therapy should be included in the initial treatment regimen for all patients with CAP requiring hospitalization. If a more sensitive rule could be derived, however, it might be possible to withhold treatment for Legionella in patients with low scores. More specific antibiotic therapy then would help prevent antibiotic resistance. Such a prediction rule would require prospective validation on consecutive patients with CAP to determine its utility for guiding decisions about initial antibiotic therapy in this clinical setting.

The newly revised American Thoracic Society guidelines for the initial management of adults with CAP advise the use of empiric therapy directed at Legionella pneumonia in all patient groups, including ambulatory and hospitalized patients with nonsevere presentations. Our conclusion that anti-Legionella therapy should be part of the initial antimicrobial regimen is not adversely affected by the new guidelines and only serves to corroborate them.

Abbreviations: CAP = community-acquired pneumonia; CI = confidence interval; DFA = direct fluorescent antibody; ROC = receiver operating characteristic; WUH = Winthrop-University Hospital

This research was supported in part by grant No. DK02756–01 (T.F.I.).

Table Graphic Jump Location
Table 1. WUH Scoring System With Examples*
* 

Example 1 shows that there is a high probability of legionellosis upon hospital admission. Example 2 demonstrates that the diagnosis of legionellosis upon hospital admission is probable. Example 3 shows that upon hospital admission it is unlikely that the patient has legionellosis. Values in parentheses represent the WUH point score.

Table Graphic Jump Location
Table 2. Baseline Characteristics of the Legionella and Pneumococcus Groups*
* 

Values given as No. (%), unless otherwise indicated.

 

Three in the pneumococcus group were receiving antiretrovirals and prophylactic antibiotic therapy; all others were not being treated.

 

One patient required long-term steroid use and the other was not taking any immunosuppressives.

§ 

The patient did not require long-term steroid therapy.

 

Metastatic lung cancer.

Table Graphic Jump Location
Table 3. WUH Point Score Comparison: Main Analysis*
* 

Values given as No. (%), unless otherwise indicated.

Table Graphic Jump Location
Table 4. WUH Point Score Comparison for Patients With Complete Data: Subgroup Analysis*
* 

Values given as No. (%), unless otherwise indicated.

We thank Dr. Richard B. Kohler and Ms. Jennifer Smith-Davis for their assistance in compiling a portion of the data used in this study.

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Torres, A, Serra-Batlles, J, Ferrer, A, et al Severe community-acquired pneumonia: epidemiology and prognostic factors.Am Rev Respir Dis1991;144,312-318. [PubMed]
 
Cohen, ML, Broome, CV, Paris, AL, et al Fatal nosocomial Legionnaires disease: clinical and epidemiological characteristics.Ann Intern Med1979;90,611-613. [PubMed]
 
Bangsborg, JM, Jensen, BN, Friis-Moller, A, et al Legionellosis in patients with HIV infection.Infection1990;18,342-346. [PubMed]
 
Allam, AA, Kamholz, SL Legionella pneumonia and AIDS.Chest1989;95,707-708
 
MacFarlane, JT, Finch, RG, Ward, MJ, et al Hospital study of adult community-acquired pneumonia.Lancet1982;2,255-258. [PubMed]
 
Stout, JE, Yu, VL Legionellosis.N Engl J Med1997;337,682-687. [PubMed]
 
Olaechea, PM, Quintana, JM, Gallardo, MS, et al A predictive model for the treatment approach to community-acquired pneumonia in patients needing ICU admission.Intensive Care Med1996;22,1294-1300. [PubMed]
 
Keller DW, Lipman HB, Marston BJ, et al. Clinical diagnosis of Legionnaires disease using a multivariate model [abstract]. In: Proceedings of the 35th Interscience Conference on Antimicrobial Agents and Chemotherapy; September 17–20, 1995; San Francisco, CA; abstract K55.
 
Sharrar, RG, Friedman, HM, Miller, WT, et al Summertime pneumonias in Philadelphia in 1976: an epidemiologic studyAnn Intern Med1979;90,577-580. [PubMed]
 
Gregory, DW, Schaffner, W, Alford, RH, et al Sporadic cases of Legionnaires disease: the expanding clinical spectrum.Ann Intern Med1979;90,518-521. [PubMed]
 
Schneider, RF, Rosen, MJ Pneumococcal infections in HIV-infected adults.Semin Respir Infect1999;14,237-242. [PubMed]
 

Figures

Tables

Table Graphic Jump Location
Table 1. WUH Scoring System With Examples*
* 

Example 1 shows that there is a high probability of legionellosis upon hospital admission. Example 2 demonstrates that the diagnosis of legionellosis upon hospital admission is probable. Example 3 shows that upon hospital admission it is unlikely that the patient has legionellosis. Values in parentheses represent the WUH point score.

Table Graphic Jump Location
Table 2. Baseline Characteristics of the Legionella and Pneumococcus Groups*
* 

Values given as No. (%), unless otherwise indicated.

 

Three in the pneumococcus group were receiving antiretrovirals and prophylactic antibiotic therapy; all others were not being treated.

 

One patient required long-term steroid use and the other was not taking any immunosuppressives.

§ 

The patient did not require long-term steroid therapy.

 

Metastatic lung cancer.

Table Graphic Jump Location
Table 3. WUH Point Score Comparison: Main Analysis*
* 

Values given as No. (%), unless otherwise indicated.

Table Graphic Jump Location
Table 4. WUH Point Score Comparison for Patients With Complete Data: Subgroup Analysis*
* 

Values given as No. (%), unless otherwise indicated.

References

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Torres, A, Serra-Batlles, J, Ferrer, A, et al Severe community-acquired pneumonia: epidemiology and prognostic factors.Am Rev Respir Dis1991;144,312-318. [PubMed]
 
Cohen, ML, Broome, CV, Paris, AL, et al Fatal nosocomial Legionnaires disease: clinical and epidemiological characteristics.Ann Intern Med1979;90,611-613. [PubMed]
 
Bangsborg, JM, Jensen, BN, Friis-Moller, A, et al Legionellosis in patients with HIV infection.Infection1990;18,342-346. [PubMed]
 
Allam, AA, Kamholz, SL Legionella pneumonia and AIDS.Chest1989;95,707-708
 
MacFarlane, JT, Finch, RG, Ward, MJ, et al Hospital study of adult community-acquired pneumonia.Lancet1982;2,255-258. [PubMed]
 
Stout, JE, Yu, VL Legionellosis.N Engl J Med1997;337,682-687. [PubMed]
 
Olaechea, PM, Quintana, JM, Gallardo, MS, et al A predictive model for the treatment approach to community-acquired pneumonia in patients needing ICU admission.Intensive Care Med1996;22,1294-1300. [PubMed]
 
Keller DW, Lipman HB, Marston BJ, et al. Clinical diagnosis of Legionnaires disease using a multivariate model [abstract]. In: Proceedings of the 35th Interscience Conference on Antimicrobial Agents and Chemotherapy; September 17–20, 1995; San Francisco, CA; abstract K55.
 
Sharrar, RG, Friedman, HM, Miller, WT, et al Summertime pneumonias in Philadelphia in 1976: an epidemiologic studyAnn Intern Med1979;90,577-580. [PubMed]
 
Gregory, DW, Schaffner, W, Alford, RH, et al Sporadic cases of Legionnaires disease: the expanding clinical spectrum.Ann Intern Med1979;90,518-521. [PubMed]
 
Schneider, RF, Rosen, MJ Pneumococcal infections in HIV-infected adults.Semin Respir Infect1999;14,237-242. [PubMed]
 
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