Performance of SOAR (systolic blood pressure, oxygenation, age and respiratory rate) scoring criteria in community-acquired pneumonia: a prospective multi-centre study

Background: severity assessment in community-acquired pneumonia (CAP) is important as it is associated with significant mortality. In this study, we compared a previously suggested severity assessment rule for CAP- SOAR (systolic blood pressure, oxygenation, age and respiratory rate)- against the CURB-65 criteria.

Methods: we conducted a prospective study in three hospitals in Norfolk and Suffolk, UK. Consecutive patients with CAP were scored for severity with CURB-65 (n = 190), and SOAR (when there was sufficient information, n = 112). Mortality data was collected at 6 weeks.

Results: there were 100 males (53%). The age range was 18–101 years (mean 72 years, median 76 years). Sixty-five (34%) had severe pneumonia by CURB-65, and 56 patients out of 112 (50%) had severe pneumonia by SOAR. Patients with severe CAP were significantly more likely to be older, female, and to have higher urea levels and a lower PaO2:FiO2 ratio on admission. There were a total of 54 deaths during follow-up (33 of these in the SOAR-categorised group). There were 32 deaths (50%) in the severe and 22 deaths (18%) in the non-severe groups by CURB-65. There were 23 deaths (70%) in the severe and 22 deaths (30%) in the non-severe groups by SOAR. For CURB-65, sensitivity, specificity, positive and negative predictive values were 60.6, 72.2, 47.6 and 81.4%. For SOAR, the respective values were 69.7%, 58.2, 41.1 and 82.1%.

Conclusion: SOAR had demonstrably better sensitivity, but lower specificity compared with CURB-65 in this patient cohort. SOAR might be more suitable for assessing disease severity as an alternative or adjunct to CURB-65, particularly in the elderly.