Fukuchi-Manabe Score for Infection Control Measures During the Very Early COVID-19 Pandemic Period When Access to Reverse Transcription-Polymerase Chain Reaction Testing Was Poor in Japan: A Single-Center Observational Prospective Cohort Study

Abstract

Background: During the early stages of the COVID-19 pandemic in Japan, access to reverse transcription-polymerase chain reaction (RT-PCR) testing was limited. All patients with COVID-19 required hospitalization, and isolation of suspected COVID-19 patients had not yet been implemented. With the recently acquired evidence on COVID-19, it is important to develop a risk stratification system for isolation rooms in the context of limited resources for better resource management.

Objective: This study aimed to develop and validate a COVID-19 risk-scoring strategy, the Fukuchi-Manabe score, to safely stratify and manage isolation rooms, personal protective equipment (PPE), and RT-PCR testing in the context of limited RT-PCR testing and a short supply of PPE.

Methods: This single-center prospective study consecutively enrolled suspected COVID-19 adult inpatients between March 1 and August 31, 2020. The primary and secondary outcomes were a positive RT-PCR test and the occurrence of nosocomial infections during the study period, respectively. Factors related to patient history, symptoms, chest computed tomography findings, and laboratory data suggestive of COVID-19 were scored, totaled, and divided into four categories ("probable," "possible," "less likely," and "non-suspicious") based on the likelihood of COVID-19. Sensitivity, specificity, and positive and negative predictive values were evaluated for each probability category.

Findings: Twenty of 224 inpatients were positive on the RT-PCR test, including 18 "probable" patients (90.0%), one "possible" patient, and one "less likely" patient. The area under the curve (AUC) (95% confidence interval: 0.841-0.977), sensitivity, and specificity were 0.909, 90.0%, and 80.4%, respectively. The positive and negative predictive values and accuracy for the "probable" category were 0.90, 0.80, and 0.82, respectively. The mean and standard deviation of AUCs, validated by bootstrap analysis, were 0.910±0.034. No nosocomial infections were observed.

Conclusion: The Fukuchi-Manabe score will be helpful when other novel pathogens emerge in the future before the availability of genetic testing methods.

Keywords: covid-19; infection control measures; quarantine; risk-scoring strategy; sars-cov-2.

Figure 1. Chest CT imaging of typical COVID-19 pneumonia. Bilateral GGO dominant in the lower lobe and subpleural area makes a score of "3" using the Fukuchi-Manabe score

(A) Coronal chest CT images (B). Just above the tracheal bifurcation level. (C) Heart level CT: computed tomography, COVID-19: coronavirus disease 2019, GGO: ground-glass opacity

Figure 2. Chest CT imaging of atypical COVID-19 pneumonia. Unilateral GGO makes a score of "1" using the Fukuchi-Manabe score

(A) Coronal chest CT images. (B) Tracheal bifurcation level. (C) Heart level CT: computed tomography, COVID-19: coronavirus disease 2019, GGO: ground-glass opacity

Figure 3. Patient flow in a prospective cohort study as per the Fukuchi-Manabe score

COVID-19: coronavirus disease 2019, RT-PCR: reverse transcription-polymerase chain reaction, SARS-CoV-2: severe acute respiratory syndrome coronavirus 2

Figure 4. ROC curve of the Fukuchi–Manabe score. The AUC was 0.909 (95% confidence interval: 0.841–0.977), sensitivity was 90.0%, and specificity was 80.4%

ROC: receiver operating characteristic, AUC: area under the curve