Pre-discharge systolic blood pressure in hospitalized COVID-19 patients is an independent predictor of imrovement in 6-minute walk test during 1-month follow-up

Abstract

Objective: To study the relation of hypertensive status and systolic blood pressure (SBP) pre-discharge values to the dynamics of functional re-conditioning as assessed by 6-minute walk distance during the 1-month follow-up after hospitalization for COVID-19. Design and method: 6-minute walk distance (6MWD) was assessed pre-discharge in 176 patients hospitalized for COVID-19 (40% hypertensive, 47% male, mean age 53,2 ± 13,5 years) using the 20 m walkway and an extended protocol that included monitoring of peripheral pulse and capillary blood oxygen saturation (SpO2) every 30 seconds via bluetooth-connected pulse oximeter. The repeated evaluation was performed after 1 month of follow-up. Results: Hypertensive participants were characterised by older age (57,8±11,8 vs 50,7±13,9, p < 0,001), higher weight and body mass index (31,7±5,3 vs 27,4±4,4 kg/m2, p < 0,001). As a result, 6MWD in them was shorter (378±57 vs 418±75 m, p = 0,001) but no difference in reached percent of predicted distance (6MWD%) was detected (63,0±8,5 vs 63,2±11,1 %, p = 0,939). The described relation persisted at 1 month, with no difference in absolute (72±43 vs 68±43 m, p = 0,324) and percentage gain of 6MWD (12,8±6,6 vs 11,2±7,5 %, p = 0,266) between groups. Multiple regression analysis has allowed to build the model that accounted for 94% of variability in the 6MWD% gain between visits (85% for dedicated hypertensive cohort model). After adjustment for age, sex, height, weight, Remdesivir treatment, minimal SpO2 levels during acute COVID-19, changes of SpO2 and pulse rate throughout the 6MWT, SBP remained a potent independent predictor of 6MWD% gain, with 10 mmHg higher values at baseline evaluation being associated with 21,5% lesser 6MWD% gain in hypertensive subjects and 8,2% lesser – in normotensives. Conclusions: Hypertensive status did not have an impact on 6MWD% in pre-discharge COVID-19 patients. Moderate-to-high quality multiple regression models have demonstrated an independent role of SBP, demographic and anthropometric data, changes of SpO2 and pulse rate throughout the 6MWT in prediction of 6MWD% gain during 1 month after discharge, both in hypertensive and normotensive patients.