The roth score as a triage tool for detecting hypoxaemia in general practice: A diagnostic validation study in patients with possible COVID-19

Aim: To validate the Roth score as a triage tool for detecting hypoxaemia. Backgrounds: The virtual assessment of patients has become increasingly important during the corona virus disease (COVID-19) pandemic, but has limitations as to the evaluation of deteriorating respiratory function. This study presents data on the validity of the Roth score as a triage tool for detecting hypoxaemia remotely in potential COVID-19 patients in general practice. Methods: This cross-sectional validation study was conducted in Dutch general practice. Patients aged ≥18 with suspected or confirmed COVID-19 were asked to rapidly count from 1 to 30 in a single breath. The Roth score involves the highest number counted during exhalation (counting number) and the time taken to reach the maximal count (counting time). Outcome measures were (1) the correlation between both Roth score measurements and simultaneous pulse oximetry (SpO2) on room air and (2) discrimination (c-statistic), sensitivity, specificity and predictive values of the Roth score for detecting hypoxaemia (SpO2 < 95%). Findings: A total of 33 physicians enrolled 105 patients (52.4% female, mean age of 52.6 ± 20.4 years). A positive correlation was found between counting number and SpO2 (r s = 0.44, P < 0.001), whereas only a weak correlation was found between counting time and SpO2 (r s = 0.15, P = 0.14). Discrimination for hypoxaemia was higher for counting number [c-statistic 0.91 (95% CI: 0.85-0.96)] than for counting time [c-statistic 0.77 (95% CI: 0.62-0.93)]. Optimal diagnostic performance was found at a counting number of 20, with a sensitivity of 93.3% (95% CI: 68.1-99.8) and a specificity of 77.8% (95% CI: 67.8-85.9). A counting time of 7 s showed the best sensitivity of 85.7% (95% CI: 57.2-98.2) and specificity of 81.1% (95% CI: 71.5-88.6). Conclusions: A Roth score, with an optimal counting number cut-off value of 20, maybe of added value for signalling hypoxaemia in general practice. Further external validation is warranted before recommending integration in telephone triage.