Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study

TLDR

In assessing severity of community‑acquired pneumonia, the modified British Thoracic Society rule identifies patients with severe disease but fails to flag those suitable for home management. This multicentre study aimed to derive and validate a practical severity assessment model to stratify adults hospitalized with CAP into distinct management groups using data from three prospective studies in the UK, New Zealand, and the Netherlands. The authors used an 80 % derivation cohort from the combined data, applied multiple logistic regression with 30‑day mortality as the outcome to identify prognostic variables, and then tested the resulting model on the remaining 20 % validation cohort. The resulting six‑point score—confusion, urea >7 mmol/L, respiratory rate ≥30/min, low blood pressure, and age ≥65—accurately stratified mortality risk from 0.7 % to 57 % and was confirmed in an independent cohort, supporting its use to guide CAP management.

Abstract

In the assessment of severity in community acquired pneumonia (CAP), the modified British Thoracic Society (mBTS) rule identifies patients with severe pneumonia but not patients who might be suitable for home management. A multicentre study was conducted to derive and validate a practical severity assessment model for stratifying adults hospitalised with CAP into different management groups.Data from three prospective studies of CAP conducted in the UK, New Zealand, and the Netherlands were combined. A derivation cohort comprising 80% of the data was used to develop the model. Prognostic variables were identified using multiple logistic regression with 30 day mortality as the outcome measure. The final model was tested against the validation cohort.1068 patients were studied (mean age 64 years, 51.5% male, 30 day mortality 9%). Age >/=65 years (OR 3.5, 95% CI 1.6 to 8.0) and albumin <30 g/dl (OR 4.7, 95% CI 2.5 to 8.7) were independently associated with mortality over and above the mBTS rule (OR 5.2, 95% CI 2.7 to 10). A six point score, one point for each of Confusion, Urea >7 mmol/l, Respiratory rate >/=30/min, low systolic(<90 mm Hg) or diastolic (</=60 mm Hg) Blood pressure), age >/=65 years (CURB-65 score) based on information available at initial hospital assessment, enabled patients to be stratified according to increasing risk of mortality: score 0, 0.7%; score 1, 3.2%; score 2, 3%; score 3, 17%; score 4, 41.5% and score 5, 57%. The validation cohort confirmed a similar pattern.A simple six point score based on confusion, urea, respiratory rate, blood pressure, and age can be used to stratify patients with CAP into different management groups.