Results of a new score to predict the risk of rapid progression to severe disease in hospitalized patients with COVID-19, based on easily accessible data such as age, sex, BMI, dyspnea, and inflammatory parameters, were published in Open Forum Infectious Diseases. The BAS²IC score had negative and positive predictive values of 87% and 49%, respectively, based on a cut-off of greater than six points.
To develop the risk score, investigators used data from a prospective non-interventional cohort study, which included adult patients with confirmed COVID-19 hospitalized in March at Strasbourg University or Mulhouse hospitals in France. Severe disease was defined as admission to the intensive care unit (ICU) or death within 7 days after admission. Overweight and obese were defined according to the WHO as a body mass index (BMI) of ≥25 kg/m² and ≥30 kg/m², respectively. Dyspnea was defined as a score of greater than zero according to the modified Medical Research Council breathlessness scale.
In a derivation cohort of 1045 patients, researchers performed a Bayesian logistic regression to identify risk factors for severe COVID-19. Investigators identified advanced age (β coefficient = .4), male sex (β coefficient = .735), overweight (β coefficient = .490), obesity (β coefficient = .776), dyspnea (β coefficient = .913), C-reactive protein level ≥ 100 and < 200 mg/L at admission (β coefficient = .489), C-reactive protein level ≥ 200 mg/L (β coefficient = 1.397), neutrophil count ≥8000/μL (β coefficient = .747) and lymphocyte count <1000/μL (β coefficient = .364) as factors associated severe disease. The score was evaluated based on positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity in the derivation cohort. Clinically relevant cuts-offs were also determined to be NPV >85% and PPV >60%. Finally, the scores performance was validated using an external cohort of 153 patients hospitalized for COVID-19 during the same period in Colmar Hospital, France.
Investigators defined a prognostic BAS²IC score including BMI, age, sex, shortness of breath, and inflammatory parameters to screen patients who were at risk of developing early severe disease based on the previously identified prognostic factors. In a receiver-operating characteristics analysis, the area under the curve was 0.76 (0.73–0.79). Using a cut-off of greater than six points, the NPV and PPV were 87% and 49%, respectively, with a sensitivity of 93% and a specificity of 32%. At a cut-off of more than fourteen, NPV was 66%, PPV was 66%, sensitivity was 33%, and specificity was 88%.
In the validation cohort, using a cut-off of greater than 6 points, the NPV, PPV, sensitivity, and specificity were 88%, 38%, 87%, and 40%, respectively. At a cut-off of greater than fourteen points the NPV, PPV, sensitivity, and specificity were 73%, 58%, 16%, and 95%, respectively.
The BAS²IC score was based on a large multicenter prospective cohort and has several advantages over previous published scores. The score can predict the development of early complications by relying on easily accessible, simple, and inexpensive clinical and laboratory parameters. They believe the score could be easily implemented in routine clinical practice to help distinguish between low- and high-risk patients. The score also included two important risk factors not previously taken into account: patients being overweight and exhibiting certain inflammatory parameters.
The performance level of the BAS2IC score is not very high. Some factors associated with poor outcome, such as high levels of D-dimer and interleukine-6, were not taken into account. They were omitted as they are not tested for in routine clinical practice. Incorporation of other risk factors would have rendered the score difficult to use for clinicians. The study was also conducted at the beginning of the outbreak and few patients benefited from specific therapies (eg, corticosteroids, immunomodulatory treatments), which may have impacted the numbers of severe cases.
Investigators conclude that this score, which is easy to use and implement in routine practice, can help physicians identify patients at high-risk of developing early severe COVID-19. “This simple score may be useful for triage of patients with COVID-19 and to identify those who should be closely monitored.” They did however caution that BAS²IC, “should not replace common clinical sense for deciding whether the patients require hospitalization or specific therapy,” adding that further studies are needed to confirm the performance and validate proposals for COVID-19 management depending on the score.
Kaeuffer C, Ruch Y, Fabacher T, et al. The BAS²IC score: a useful tool to identify patients at high risk of early progression to severe COVID-19 [published online September 1, 2020]. Open Forum Infect Dis. doi: 10.1093/ofid/ofaa405