Thomas J. Marrie, MD

20 June, 2018

Community-acquired pneumonia, or CAP, is associated with morbidity and mortality throughout the world, yet there is great variation in treatment. A study investigated the results of CAP treatment using a critical pathway. 9,558 patients were assessed. 7,734 were enrolled in the pathway and 55% of these patients were treated as outpatients.

Epidemiological analysis confirmed that the rate of admission increased with age. The rate was significantly higher for men in all age groups over 65, and was also higher in some of the younger age groups.

Younger pneumonia patients had a higher admission rate to the intensive care unit. 20-35% of patients aged under 45 years were admitted to ICU, while only 5-10% of those aged over 80 years were admitted to ICU.

A sputum culture was taken in 5% of outpatients and 35% of inpatients with positive pathogen identification in 44% and 29%, respectively. A blood culture was performed for 20% of outpatients and 66% of inpatients with a positive identification rate of 5.2% and 6.9%, respectively. Therefore a significant number of patients with mild bacteremic pneumonia were managed at home.

58.9% of all patients in the pathway were treated with one antibiotic and this was invariably levofloxacin, administered to at least 90% of patients initially. Oral therapy worked in this pathway.

Some of the most common combination strategies included levofloxacin plus metronidazole, administered for suspected Clostridium difficile diarrhea, and levofloxacin switched to clindamycin for aspiration pneumonia.

The total mortality rate was 8.1%, with almost 30% of deaths occurring within three days of admission. The mortality rate according to time from admission then dropped until increasing again at more than 28 days, often associated with exacerbations in co-morbidity. Multivariate analysis demonstrated that different factors predict early versus late mortality.

Analysis of mortality according to severity of pneumonia (defined by the Pneumonia Severity Index or PSI score ) demonstrated that patients in classes I, II and III had a lower risk of mortality whereas classes IV and V had a higher mortality risk.

Risk of death was closely related to age and severity of pneumonia by risk score. However time to receiving first antibiotic was not associated with an increased risk of mortality. Socio-economic status as measured by income had no significance.

Using PSI score, risk classes I and II had a very low mortality rate, class III had a mortality rate of 2.1%, rising to 6.5% in Class IV. The highest mortality rate was 23.5% in class V, slightly lower than other reports, possibly due to the exclusion of ICU patients.

Functional status on admission was associated with different mortality rates. Patients that required a wheelchair or were bedridden had mortality rates over 20%.

Patients able to rise and walk three meters in less than 20 seconds had a 1.6% mortality rate compared to a 4.1% mortality for those who failed this test. Impaired mental status was also associated with increased mortality.

The mortality rate for patients according to antibiotic administered showed that those treated with levofloxacin only or cefuroxime axetil plus azithromycin had a lower mortality rate compared to patients treated with other agents.

Early mortality within the first five days of admission was associated with poor functional status, low lymphocyte count and high potassium levels. Use of the clinical pathway was protective.

Late mortality was higher in patients with functional impairment and those who consulted a specialist. In contrast, levofloxacin was the only factor protective against late mortality. This study confirmed that the clinical pathway was beneficial for the treatment of pneumonia and oral levofloxacin is adequate for many patients requiring admission for CAP.