Admission is not always necessary for patients with community-acquired pneumonia in risk classes IV and V diagnosed in the emergency room

Department of Medicine, University of Alberta, Edmonton, Alberta Correspondence: Dr Thomas J Marrie, Faculty of Medicine and Dentistry, 2J2.01 – Walter C Mackenzie Health Sciences Centre, 8440–112 Street, Edmonton, Alberta T6G 2R7. Telephone 780-492-9728, fax 780-492-7303, e-mail tom.marrie@ualberta.ca TJ Marrie, JQ Huang. Admission is not always necessary for patients with community-acquired pneumonia in risk classes IV and V diagnosed in the emergency room. Can Respir J 2007;14(4):212-216.

C ommunity-acquired pneumonia (CAP) is a common and serious illness affecting over five million people in the United States each year, of whom approximately 600,000 are hospitalized, resulting in a cost of approximately US$9 billion per annum (1,2).In a carefully conducted study of CAP, Fine et al (3) developed a pneumonia-specific severity of illness scoring system based on 20 factors, including demographic, clinical and laboratory features.Patients were grouped into five risk classes for mortality -classes I to III (90 points or less) were at low risk for death, while the mortality rates were 9% in class IV and 27% in class V (3).Based on these data, the authors concluded that patients in risk classes I and II could generally be managed on an ambulatory basis and that patients in classes IV and V should be admitted (3).It should be noted that age is a major factor in this scoring system, because male patients receive one point per year of age, while female patients have 10 points subtracted from the total age points.Thus, it is usually elderly patients who are in risk classes IV and V.
In a prospective study of CAP (4), we noted that 316 of 2251 patients (14%) in classes IV and V were managed on an ambulatory basis.The present paper compares the two groups of patients and provides data that should allow physicians to manage some of their class IV and V patients in an ambulatory setting.

Study sites
The present study involved all six hospitals and one clinic with an emergency room in the Edmonton, Alberta, area.There were two ©2007 Pulsus Group Inc.All rights reserved

ORIGINAL ARTICLE
tertiary care hospitals, two hospitals that provided secondary and some tertiary care, and two community hospitals.The study was approved by the Research Ethics Committee at the University of Alberta, Edmonton, Alberta.

Development of a pneumonia pathway
A multidisciplinary team developed a comprehensive pathway for the management of CAP (5).The pathway consisted of an admission guideline (5).In general, treatment on an outpatient basis was recommended for those in risk classes I to III and on an inpatient basis for those in classes IV and V; however, a note on each guideline indicated that physician judgment was to take precedence in the final decision as to site of care.In addition, medical staff were given preprinted orders covering the routine aspects of care, an algorithm for administration and discontinuation of supplemental oxygen and antimicrobial therapy (levofloxacin orally or cefuroxime plus azithromycin intravenously were the options provided), but other options were not prohibited.Reminders to medical staff regarding assessment of vaccination status for pneumococcal and influenza vaccines were provided, and a recommendation for administration of these vaccines, if indicated, was included in the order sheet.In addition, counselling and literature regarding cessation of smoking were made available to those who were tobacco smokers.
The inpatient components of the pathway (6)(7)(8) are not detailed here because they are not pertinent to the present study.A follow-up phone call was made to patients who were discharged from the emergency department within 72 h of discharge.

Pneumonia definition
A diagnosis of pneumonia was defined as two or more symptoms or signs of CAP (cough [productive or nonproductive], pleuritic chest pain, shortness of breath, temperature higher than 38°C, and crackles or bronchial breathing on auscultation) plus radiographic evidence of pneumonia as interpreted by the emergency room physician or internal medicine consultant.Patients were excluded from the pathway if they required admission to intensive care from the emergency room, or were thought to have aspiration pneumonitis (defined as pulmonary opacities with recent loss of consciousness, vomiting or observation of respiratory distress within 30 min of feeding), tuberculosis or cystic fibrosis.Pregnant and nursing mothers and immunosuppressed patients (greater than 10 mg prednisone per day for more than one month or other immunosuppressive drugs) were also excluded.Those with HIV infection were excluded if their CD 4 counts were less than 250/mm 3 .During the second year of the study, patients with aspiration pneumonia were included (during the first year of the study the authors could not agree on a therapeutic regimen for patients with aspiration pneumonia).All patients with aspiration pneumonia were admitted.

Data analysis
For analyses of data, SPSS version 12.0 was used (SPSS Inc, USA).Predisposing factors, clinical, laboratory and radiological findings, and mortality in ambulatory and admitted patients were compared using a univariate model.The predictors with P<0.10 in the univariate analysis were used in the multivariate analysis.Backward selection with the entry probability of 0.05 and removal probability of 0.1 were used to select the final model.The Hosmer-Lemeshow lack-of-fit test was used to evaluate the adequacy of the logistic regression models.

RESULTS
Three hundred nineteen of the 2354 patients in risk groups IV and V (13.5%) were treated as outpatients.The characteristics of the ambulatory and hospitalized patients are shown in Table 1.Male patients predominated among class IV and V patients treated on an ambulatory basis (233 of 316 patients [73.7%]).The admission rates of class IV and V patients varied by site, from 83.2% to 89.8%.Site G had outpatient facilities only, and patients from that site who required admission were transferred to one of the other sites.It is noteworthy that the patients' residence before admission seemed to influence the admission decision, in that 82.5% of those who were living at home were admitted, while 100% of those who were living in a chronic care facility were admitted.Not unexpectedly, all eight homeless persons and seven persons residing in jail were admitted.Those who were discharged from the emergency department were less likely to have definite pneumonia on chest radiograph (as read by a radiologist) (37% versus 51.4% for the admitted group).Other key differences were: 65.5% of the ambulatory group was fully functional, compared with 44% of the admitted group; 9% of the ambulatory group was in class V, compared with 36% of the admitted group; and aspiration pneumonia was more common in the admitted group.Only 0.6% of the ambulatory patients died, compared with 13.8% of the hospitalized patients.
Table 2 shows the percentage of outpatients and inpatients with selected symptoms.
The objectively measured physiological parameters of temperature, respiratory rate and pulse rate were all higher in the admitted group.Table 3 gives vital signs and laboratory data for the two groups of patients expressed as the percentage with an abnormal value.It is noteworthy that oxygen saturation was less than 90% in 25% of the outpatients and 57.6% of the inpatients, and that 46.8% and 59%, respectively, had abnormal urea levels.The potassium level was abnormal in 15.6% of outpatients and 21.6% of inpatients.Table 4 shows the number and types of comorbidities in each group.Nineteen per cent of the outpatients and 39.4% of the inpatients had three or more comorbidities.In general, a much higher percentage of the inpatients had any of the indicated comorbidities than the outpatients.
Table 5 gives the blood culture results for both groups.Only 22% of the outpatients and 68% of the inpatients had these tests completed.The positivity rates were 2.8% and 7.9%, respectively.Only two of the outpatients had positive blood cultures -one for Streptococcus pneumoniae and the other for Staphylococcus aureus.Both were subsequently admitted.Thirty-nine per cent of the 105 isolates from the inpatient group were positive for S pneumoniae.It is interesting to note that S aureus accounted for 17% and Escherichia coli for 16% of the isolates.Fifteen other micro-organisms made up the remaining 27.6% of isolates.
The results of the multivariate analysis of the factors predictive of admission are given in Table 6.The following factors were independently predictive of admission: definite or possible pneumonia on chest radiograph as read by a radiologist, functional impairment, altered mental status, substance abuse, psychiatric disorder, abnormal white blood cell count, abnormal lymphocyte count, oxygen saturation less than 90% and antibiotic administration in the week before admission.If chest pain was present, admission was less likely.Follow-up of the outpatients revealed that only two died.

DISCUSSION
Just over 13% of the patients in risk classes IV and V were treated as outpatients.In the original study (3) describing this severity of illness scoring system for CAP, only 41 of 2287 patients (1.8%) in risk classes IV and V were treated as outpatients.However, the Fine et al (3) study differed from the current study in that only patients with radiographs read by a radiologist were enrolled.In our study, only 50% of the group treated as outpatients had radiologist-confirmed pneumonia.However, even if one adjusts for this there are still at least three times as many patients treated as outpatients in these risk groups than in the original study.It is noteworthy that in a randomized trial of a critical pathway for the treatment of pneumonia conducted at 19 hospitals in Canada from January to July 1998 (4), 87% of the patients in risk classes IV and V in the intervention arm, and 88% in the conventional treatment arm were admitted to hospital -values identical to those in the current study.
Our study also provides information as to which patients in risk classes IV and V are likely to do well with treatment on an ambulatory basis -patients who are fully functional, mentally alert, not hypoxemic, not substance abusers, do not have a concomitant psychiatric diagnosis, have normal total white blood cell and lymphocyte counts and normal respiratory rates, and have not received antibiotics in the past week.In a detailed analysis of factors that predicted mortality in the entire study population requiring admission to hospital, we noted that some of the factors that were predictive of admission in the class IV and V patients (in addition to being in one or the other of these two risk classes) were predictive of mortality (4).These included functional status, abnormal lymphocyte count and substance abuse, in addition to age and risk score.
We also noted that 13.7% of those treated on an ambulatory basis required home care.This has the obvious implication   that such services have to be available to care for these patients.
Only 22% of the outpatients had blood cultures, and of these, only two patients had a positive result -one with S pneumoniae and one with S aureus.Both these patients were admitted (the only ones who required subsequent admission).
Our study has some limitations.Our follow-up consisted of a phone call at 72 h after discharge and checking hospital records for subsequent admission.Thus, we may have missed patients who were admitted to hospitals outside our area following discharge from the emergency department, and we also could have underestimated the number of patients who died for the same reasons.

CONCLUSIONS
We have shown that a significant percentage of patients in risk classes IV and V can be safely treated at home.In addition, we have elucidated factors which will help the clinician in selecting the subset of patients in these two risk classes who can be sent home.Other micro-organism isolated, n

Streptococcus pyogenes 4
Streptococcus viridans 3 Marrie and HuangCan Respir J Vol 14 No 4 May/June 2007 214 Admission not always necessary for class IV and V CAP Can Respir J Vol 14 No 4 May/June 2007 215

TABLE 1 -
CONTINUEDA comparison of the single-visit outpatient and admitted community-acquired pneumonia populations in risk classes IV and V *Mean ± SD; † Data excluded inpatients who died or remained in the hospital; ‡ X-ray reports for 15 inpatients were missing; § Data for 112 inpatients were not recorded.ADLs Activities of daily living; CAP Community-acquired pneumonia; ER Emergency room

TABLE 3
Comparisons of abnormal vital signs and laboratory values for single-visit community-acquired pneumonia outpatients and inpatients in risk classes IV and V

TABLE 5
Comparisons of blood culture results between single-visit outpatient and admitted community-acquired pneumonia population in risk classes IV and V