Association between prehospital shock index and mortality among patients with COVID-19 disease

BACKGROUND: There exists a need for prognostic tools for the early identification of COVID-19 patients requiring intensive care unit (ICU) admission and mortality. Here we investigated the association between a clinical (initial prehospital shock index (SI)) and biological (initial prehospital lactatemia) tool and the ICU admission and 30-day mortality among COVID-19 patients cared for in the prehospital setting. METHODS: We retrospectively analysed COVID-19 patients initially cared for by a Paris Fire Brigade advanced (ALS) or basic life support (BLS) team in the prehospital setting between 2020, March 08th and 2020, May 30th. We assessed the association between prehospital SI and prehospital lactatemia and ICU admission and mortality using logistic regression model analysis after propensity score matching with Inverse Probability Treatment Weighting (IPTW) method. Covariates included in the IPTW propensity analysis were: age, sex, body mass index (BMI), initial respiratory rate (iRR), initial pulse oximetry without (SpO2i) and with oxygen supplementation (SpO2i.O2), initial Glasgow coma scale (GCSi) value, initial prehospital SI and initial prehospital lactatemia. RESULTS: We analysed 410 consecutive COVID-19 patients [254 males (62%); mean age, 64 ± 18 years]. Fifty-seven patients (14%) deceased on the scene, of whom 41 (72%) were male and were significantly older (71 ± 12 years vs. 64 ± 19 years; P 〈10(−3)). Fifty-three patients (15%) were admitted in ICU and 39 patients (11%) were deceased on day-30. The mean prehospital SI value was 1.5 ± 0.4 and the mean prehospital lactatemia was 2.0 ± 1.7 mmol.l(−1). Multivariate logistic regression analysis on matched population after IPTW propensity analysis reported a significant association between ICU admission and age (adjusted Odd-Ratio (aOR), 0.90; 95% confidence interval (95%CI): 0.93–0.98;p = 10(−3)), SpO2i.O2 (aOR, 1.10; 95%CI: 1.02–1.20;p = 0.002) and BMI (aOR, 1.09; 95% CI: 1.03–1.16;p = 0.02). 30-day mortality was significantly associated with SpO2i.O2 (aOR, 0.92; 95% CI: 0.87–0.98;p = 0.01 P < 10(−3)) and GCSi (aOR, 0.90; 95% CI: 0.82–0.99;p = 0.04). Neither prehospital SI nor prehospital lactatemia were associated with ICU admission and 30-day mortality. CONCLUSION: Neither prehospital initial SI nor lactatemia were associated with ICU admission and 30-day mortality among COVID-19 patients initially cared for by a Paris Fire Brigade BLS or ALS team. Further prospective studies are needed to confirm these preliminary results.