CURB-65 Score Calculator: A tool for Assessing Pneumonia Severity

The available literature shows that extensive research was done to assess the performance of the CURB-65 score, which has been utilized extensively to predict ICU admissions and mortality rates in patients with community-acquired pneumonia (CAP). This scoring system demonstrates several notable characteristics (and some limitations): ^{[1], [2]}

1. It demonstrates a very high sensitivity of 78.4% for ICU admissions and 92.8% for mortality prediction. However, it has shown low specificity, as patients with low scores (≤2) are still frequently admitted to the ICU. One study reported an area under the curve (AUC) of 0.73-0.77, with mortality rates of 0.6% for a score of 0-1, 5.7% for a score of 2, and 12.8% for a score of 3-5. ^[3]

2. Another study comparing the CURB-65 score to the NEWS score, involving 570 CAP patients with a median age of 74, found that the CURB-65 score had a good discriminatory power with an AUC of 0.728, similar to the NEWS score (0.710), with no statistical difference between them. ^[4]

3. The CURB-65 score has shown associations with both 30-day mortality rates and the need for mechanical ventilation. In addition, there are no significant statistical differences between the CURB-65 score and the simpler CRB-65 score. Both scores exhibit very similar AUC values at 0.870 and 0.864, respectively, for predicting 30-day mortality rates. ^[5]

   A study noted that patients with a CURB-65 score of 2 could be further categorized into two groups with statistically different mortality rates based on the PSI risk class: Classes I-III had a 2.6% 30-day mortality, while PSI classes IV-V had an 11.1% mortality rate. For scores greater than or equal to 3, the majority of patients (92.6%) fell into PSI risk classes IV-V, and the mortality rate in this group was 28.5%. These conclusions were drawn from a prospective study involving 1776 patients over approximately four years. ^[5]

4. A study conducted in 2020 on 279 patients with COVID-19 showed that a high CURB-65 score (≥3) was strongly associated with poor outcomes, with hazard ratios of 1.84 for a score of 2 and 4.18 for a score of ≥3. Notably, 21.1% of patients with a score of 0-1 still experienced poor outcomes, indicating the score's low specificity, particularly in the context of COVID-19. ^[6]

5. In a study comparing the CURB-65 score to the PSI risk score in 408 cases of CAP, the PSI risk score demonstrated higher sensitivity and specificity than the CURB-65 score. The PSI score was a better predictor of 30-day mortality at high scores (PSI IV-V) and ICU admissions at low scores (PSI I-II), albeit with increased diagnostic complexity. The authors emphasized the need for a new score that maintains relative ease-of-use while providing greater precision than the CURB-65 score. ^[7]

While the CURB-65 score has proven useful in assessing the severity of CAP, its limitations in terms of specificity and performance in certain contexts, such as COVID-19, highlight the need for further research and the development of improved scoring systems.