Empiric management of community-acquired pneumonia in Australian emergency departments

Community-acquired pneumonia (CAP) produces significant worldwide morbidity and mortality.1 Use of antibiotics for management of respiratory tract infections, including CAP, has been estimated to represent 75% of global antibiotic consumption,2 so judicious antibiotic prescribing for respiratory conditions is essential. Australian data on the incidence and management of CAP are lacking,3 although it has been estimated that CAP occurs in two per 1000 of the adult population per year and represents 2% of all overnight hospital admissions.4

Initial antibiotic management of CAP in hospital emergency departments (EDs) is mostly empiric. Causative organisms are typically unknown at presentation and are not always detected despite extensive diagnostic testing.5 Therefore, it is important to ensure that initial antibiotic choice covers the key bacterial pathogens likely to be responsible for the disease: Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella species.1,3,6 Patients with severe disease may require broad-spectrum antibiotic therapy to cover Legionella pneumophila, Staphylococcus aureus and enteric gram-negative bacilli.6 The readily available and widely accepted national guidelines, Therapeutic guidelines: antibiotic (Guidelines)6 advocate use of the pneumonia severity index (PSI),7 and empiric antibiotic therapy based on the most likely bacterial pathogens and disease severity.

CAPTION (Community-Acquired Pneumonia: Towards Improving Outcomes Nationally) is a multicentre quality improvement study funded and supported by the National Prescribing Service.8 The project aims to promote and implement the CAP recommendations of the Guidelines in Australian EDs. The first stage of the project involved collecting data on CAP management of adult patients in participating hospital EDs before the commencement of targeted education or interventions. This article evaluates current CAP management practices against the Guidelines.

Participating hospitals were recruited on a voluntary basis through state-based quality use of medicines organisations. Endorsement by institutional ethics committees in each participating hospital was required,9 with some hospitals requiring a full ethics committee review before any study-related activities could begin.

A retrospective medical record review was conducted on 20 consecutive adult patients presenting to the ED with a presumptive diagnosis of pneumonia documented by the attending ED doctor. Patients were identified by medical record coding using the International Classification of Diseases, 10th revision, Australian Modification (ICD-10-AM) or through ED electronic information systems. Medical records were reviewed according to predefined exclusion criteria (Box 1). Patients not prescribed antibiotics in the ED were excluded.

Data collected included:

• patient demographics;

• documented use of the PSI;

• placement after ED;

• length of stay;

• inpatient mortality;

• prior antibiotic use;

• antibiotics initiated in the ED;

• medical team initiating antibiotic therapy; and

• penicillin allergy (nil documented, immediate [urticaria, angioedema, bronchospasm or anaphylaxis within 1 hour of drug administration] or non-immediate hypersensitivity).

Data required to calculate a PSI score were also collected (Box 2). Electronic pathology and radiology reporting systems were consulted if data were not located in the medical records. Undocumented data were considered normal. If insufficient information was provided to determine the nature of a documented penicillin allergy, the reaction was assumed to be non-immediate.

A data collection form was developed by quality use of medicines groups in collab-oration with the National Prescribing Service, and was piloted in two hospitals. De-identified data were entered into an electronic database, Auditmaker. The database was designed to automatically calculate the PSI and assess concordance of initial management (PSI and antibiotic therapy prescribed) based on the presumptive diagnosis. An automated feedback report for each hospital described all data collected and concordance with the Guidelines. The automated PSI calculation and feedback report functionality were validated during the pilot phase.

Thirty-seven hospitals participated: 22 principal referral hospitals, six large major city hospitals, four large regional hospitals, four medium hospitals and one private hospital.10 No hospitals from tropical regions of Australia were included.

We identified 740 CAP ED presentations. Thirteen were excluded because antibiotics were not prescribed in the ED, and another 36 were excluded because the presentation occurred before publication of the Guidelines (April 2003). In total, 691 CAP presentations (April 2003 to February 2005) were included in the baseline cohort. The mean age was 63 years (range, 18–103), 55% were older than 65 years, and 54% were men.

There are few published audits on current management of lower respiratory infections in Australian hospitals.11,12 CAPTION provides cross-sectional data from 37 hospitals of varying types across Australia. This audit has demonstrated that documented use of the PSI is low (5%) and that initial empiric antibiotic therapy is, in general, not concordant with national guidelines (18% concordance).

Certain limitations of the study must be considered, including the retrospective patient identification and data collection and the number of personnel collecting the data. In addition, the sample size of 20 patients per hospital may not be representative of the broader prescribing habits. The use of ICD-10-AM codes restricts identification of patients to those with a documented respiratory illness at the time of discharge. Patients who presented to the ED with CAP but were documented to have a different diagnosis at discharge may have been excluded. It is also acknowledged that relying on documentation in medical notes/progress notes may be thought to weaken the PSI tool. However, the PSI was derived and validated retrospectively in separate cohorts of 38 039 inpatients and 2287 inpatients and outpatients, with the assumption that any missing values were normal.7

The low documented use of the PSI may reflect a lack of awareness or perceived usefulness of the tool. Alternatively, it may reflect lack of documentation by those using the PSI. Doubts have been raised regarding the suitability of the PSI beyond its originally intended purpose of identifying low-risk CAP patients amenable to outpatient therapy. The strong influence of age and comorbidities on the PSI score has been cited as a major problem likely to result in severely unwell younger CAP patients being “missed”.13 We argue firstly that the Guidelines recommendations are qualified by advising caution on the application of the PSI: “choice of management options using the PSI is a guide only and should always take into account the patient’s clinical and social context”. Secondly, data emerging from the ongoing Australian Community-Acquired Pneumonia Study indicate that the PSI is superior to both the British Thoracic Society’s CURB-65 and the modified American Thoracic Society criteria in predicting CAP severity.14 However, all three tools underestimate severity in selected patients requiring admission to an intensive care unit.14 Finally, the Victorian Coroner recently recommended use of a pneumonia severity assessment tool at a Victorian hospital; the hospital subsequently adopted the PSI.15

Recommendations for empiric antibiotic therapy vary around the world,1,16 with ongoing debate surrounding the most appropriate IV β-lactam antibiotic. Debate is fuelled by the fact that various broad- and narrow-spectrum antibiotics are effective; hence, it is not surprising that we found no difference in ALOS or mortality when non-concordant antibiotics were used. However, local and international opinion leaders have expressed concern over the frequent use of third-generation cephalosporins as empiric treatment for CAP and potential “collateral damage” associated with their use.17-19 The Guidelines recommend these agents for patients with severe disease (class V) or patients with a non-immediate penicillin allergy requiring intravenous therapy. In this study, 114 patients (16%) satisfied these criteria; however, 44% of patients were prescribed ceftriaxone or cefotaxime. This result is consistent with previous Australian studies, which also demonstrated a high level of third-generation cephalosporin use outside Guidelines recommendations.12,20

The issue of antibiotic monotherapy with a β-lactam antibiotic or “atypical” cover versus combination therapy of a β-lactam and “atypical” cover in empiric management of CAP continues to be vigorously debated.1,21-23 The Guidelines recommend that all CAP patients receive combination therapy6 with two exceptions: moxifloxacin/gatifloxacin is recommended for patients with immediate hypersensitivity to penicillin, and the addition of gentamicin is recommended for all class V patients prescribed IV benzylpenicillin and IV erythromycin. In this audit, 21% of patients were prescribed monotherapy (excluding moxifloxacin monotherapy) in the ED. More than half of these patients (54%) had moderate to severe disease (class III–V).

In this cohort, 28% of patients had been prescribed antibiotic therapy before presenting to the ED. Perceptions of failed oral antibiotic therapy in the community, or oral intolerance, may have influenced prescribers to initiate IV antibiotic therapy in the ED, irrespective of disease severity.

The CAP management algorithm in the Guidelines recommends alternative antibiotic choices for patients with a penicillin allergy. To ensure the most appropriate alternative is prescribed, a detailed history of penicillin reaction is needed. At least seven patients in this audit were documented to have a non-specific penicillin allergy, with antibiotic choice therefore likely to have been based on an assumption as to the type of previous reaction to penicillin. Additionally, 15 patients with documented immediate hypersensitivity were prescribed a cephalosporin and six patients with non-immediate hypersensitivity were prescribed penicillin. Although no adverse effects were reported, prescribing was inappropriate in these patients given the documented allergies, demonstrating the need to improve both knowledge about penicillin allergy and documentation of previous adverse drug reactions.

Therapeutic guidelines: antibiotic has been typically accepted as the best practice standard for antimicrobial prescribing in Australian hospitals and general practice. However, clinical judgement remains paramount and individual patients’ clinical and social needs should always be considered. As such, attaining 100% concordance with the Guidelines is not necessary or appropriate. Nevertheless, it is important that clinicians be aware of current guidelines to ensure that clinical judgement is complemented by the most up-to-date knowledge and best standard of care.

Dissemination of guidelines alone is not effective in influencing prescribing practice.24,25 A suite of tailored interventions, including academic detailing, audit and feedback, posters, stickers, PSI calculators and electronic point-of-prescribing prompts will be made available through CAPTION to assist in implementing Guideline recommendations. Further audits will be conducted to evaluate the effect of these interventions and to inform future intervention activities.

3 Management of community-acquired pneumonia in adults using the pneumonia severity index from Therapeutic guidelines: antibiotic. Version 126

Reproduced with permission from Therapeutic Guidelines Limited.