COMMUNITY-ACQUIRED PNEUMONIA - ETIOLOGY AND USEFULNESS OF SEVERITY CRITERIA ON ADMISSION

Background - Community acquired pneumonia remains an important cause o f hospital admission and carries an appreciable mortality, Criteria fo r the assessment of severity during admission have been developed by t he British Thoracic Society (BTS). A study was performed to determine the sensitivity and specificity of a severity rule based on a modifica tion of the BTS prognostic rules applied on admission, to compare seve rity as assessed by medical staff with the modified rule, and to deter mine the microbiological cause of community acquired pneumonia in Chri stchurch. Methods - A 12 month study of all adults admitted to Christc hurch Hospital with community acquired pneumonia was undertaken. Three hundred and sixteen consecutive patients with suspected community acq uired pneumonia were screened for inclusion, Variables obtained from t he history, examination, investigations, and initial treatment were ex amined for association with mortality. Results - Two hundred and fifty five patients met the inclusion criteria. Their mean age was 58 years (range 18-97). A microbiological diagnosis was made in 181 cases (71% ), Streptococcus pneumonia (39%), Mycoplasma pneumonia (16%), Legionel la species (11%), and Haemophilus influenzae (11%) being the most comm only identified organisms. Patients had a 36-fold increased risk of de ath if any two of the following were present on admission: respiratory rate greater than or equal to 30/min, diastolic BP less than or equal to 60 mm Hg, urea >7 mmol/1, or confusion. The severity rule identifi ed 19 of the 20 patients who died and six of eight patients admitted t o the intensive care unit acquired pneumonia. The sensitivity of the m odified rule for predicting death was 0.95 and the specificity 0.71. I n 47 cases (21%) the clinical team appeared to underestimate the sever ity of the illness. Conclusions - The organisms responsible for commun ity acquired pneumonia in Christchurch are similar to those reported f rom other centres except for Legionella. species which were more commo n than in most studies. The modification of the BTS prognostic rules a pplied as a severity indicator at admission performed well and could b e incorporated into management guidelines.