CALL Score and RAS Score as Predictive Models for Coronavirus Disease 2019

Abstract

Background: Coronavirus disease 2019 (COVID-19) is a novel infectious disease of multi-system involvement with significant pulmonary manifestations. So far, many prognostic models have been introduced to guide treatment and resource management. However, data on the impact of measurable respiratory parameters associated with the disease are scarce. Objective: To demonstrate the role of Comorbidity-Age-Lymphocyte count-Lactate dehydrogenase (CALL) score and to introduce Respiratory Assessment Scoring (RAS) model in predicting disease progression and mortality in COVID-19. Methodology: Data of 252 confirmed COVID-19 patients were collected at Pak Emirates Military Hospital (PEMH) from 10th April 2020 to 31st August 2020. The CALL score and proposed factors of RAS model, namely respiratory rate, oxygen saturation at rest, alveolar arterial gradient and minimal exercise desaturation test, were calculated on the day of admission. Progression of disease was defined and correlated with measured variables. Univariate and multivariate Cox regression analysis for each variable, its hazard ratio (HR) and 95% confidence interval (CI) were calculated, and a nomogram was made using the high-risk respiratory parameters to establish the RAS model. Results: Progression of disease and death was observed in 124 (49.2%) and 49 (19.4%) patients, respectively. Presence of more than 50% of chest infiltrates was significantly associated with worsening disease and death (p-value <0.001). Death was observed in 100% of patients who had critical disease category on presentation. Regression analysis showed that the presence of comorbidity (n: 180), in contrast to other variables of CALL score, was not a good prognosticator of disease severity (p-value: 0.565). Nonetheless, the CALL model itself was validated to be a reliable prognostic indicator of disease progression and mortality. Some 10 feet oxygen desaturation test (HR: 0.99, 95%CI: 0.95-1.04, p-value: 0.706) was not a powerful predictor of the progression of disease. However, respiratory rate of more than 30 breaths/minute (b/m) (HR: 3.03, 95%CI: 1.77-5.19), resting oxygen saturation of less than 90% (HR: 2.41, 95%CI: 1.15-5.06), and an elevated alveolar-arterial oxygen gradient (HR: 2.14, 95%CI: 1.04-4.39) were considered statistically significant highrisk predictors of disease progression and death, in the formed RAS model. The model resulted in 85% (95%CI: 80%-89%) of area under the receiver operating characteristic curve (AUROC), with substantial positive (76%, 95%CI: 68%-83%) and negative predictive values (80%, 95%CI: 73%-87%) for a cutoff value of seven. Patients with higher CALL and RAS scores also resulted in higher mortality. Conclusion: CALL and RAS scores were strongly associated with progression and mortality in patients with COVID-19.

Clinical Performance of the Call Score for the Prediction of Admission to Icu and Death in Hospitalized Patients With Covid-19 Pneumonia in a Reference Hospital in Peru

“…Similarly, when the model was evaluated in the Italian population, the CALL score’s predictive power as a predictor of hospital mortality was good (AUC 0.768, IC95%: 0.705 to 0.823), differing from our result[8]. And in another study conducted in Pakistan, the call score was strongly associated with progression and mortality in patients with COVID-19[9]. The results show the importance of evaluating the validity of the clinical prediction rules developed in other countries for use in our population.…”

Comparison of the efficacy of PSI, CURB-65, CALL and BCRSS in predicting prognosis and mortality in COVID-19 patients

“…In studies comparing scoring systems in COVID-19 patients, the effects of comorbidity and symptoms on mortality were also evaluated. Kamran et al suggested that comorbidity was not area under the curve: (p = 0.565) for mortality (7) while another study evaluating 52 intensive care patients with COVID-19 reported a relationship between advanced age and comorbidities and mortality (8). Zhang et al, examined 80 patients and found a significant relationship between cardiac diseases and hypertension and mortality (9) whereas Zhu et al retrospectively observed that among 181 patients with COVID-19, comorbidities were not predictive of mortality (10).…”

“…The CALL scoring system involves the evaluation of comorbidities, age, lymphocyte, and lactate dehydrogenase, which have been emphasized to play a role in COVID-19 since the emergence of the disease, and studies have been conducted to investigate the effect of these parameters on mortality. In a study examining 252 patients with COVID-19, it was shown that CALL was a reliable model for predicting mortality and determining the progression of the disease (7). In another study, Grifoni et al similarly determined that CALL was a reliable model for predicting mortality in patients with COVID-19 but noted that it did not show disease progression at a sufficient level (19).…”

Impact of preemptive hospitalization on health outcomes at the temporary COVID-19 hospital in Mexico City: a prospective observational study

“… 12 , 20 It has been shown that the CALL score is an accurate and easy to use model for predicting the risk of progression in patients with COVID-19. 5 , 21 Therefore, we evaluated the effect preemptive hospitalization had on patient outcomes when stratifying patients by CALL score. In patients at a higher risk of disease progression (CALL score ⩾8), there were significantly fewer patients requiring HFNC (23.2% versus 44.2%), admission to the ICU (11.9% versus 23.9%) or IMV (11.9% versus 22.5%) when compared with patients who were not preemptively hospitalized.…”