The Perme Mobility Index: A new concept to assess mobility level in patients with coronavirus (COVID-19) infection.

Introduction: The Coronavirus Disease 2019 (COVID-19) outbreak is evolving rapidly worldwide. Data on the mobility level of patients with COVID-19 in the intensive care unit (ICU) are needed.
Objective: To describe the mobility level of patients with COVID-19 admitted to the ICU and to address factors associated with mobility level at the time of ICU discharge.
Methods: Single center, retrospective cohort study. Consecutive patients admitted to the ICU with confirmed COVID-19 infection were analyzed. The mobility status was assessed by the Perme Score at admission and discharge from ICU with higher scores indicating higher mobility level. The Perme Mobility Index (PMI) was calculated [PMI = ΔPerme Score (ICU discharge-ICU admission)/ICU length of stay]. Based on the PMI, patients were divided into two groups: "Improved" (PMI > 0) and "Not improved" (PMI ≤ 0).
Results: A total of 136 patients were included in this analysis. The hospital mortality rate was 16.2%. The Perme Score improved significantly when comparing ICU discharge with ICU admission [20.0 (7-28) points versus 7.0 (0-16) points; P < 0.001]. A total of 88 patients (64.7%) improved their mobility level during ICU stay, and the median PMI of these patients was 1.5 (0.6-3.4). Patients in the improved group had a lower duration of mechanical ventilation [10 (5-14) days versus 15 (8-24) days; P = 0.021], lower hospital length of stay [25 (12-37) days versus 30 (11-48) days; P < 0.001], and lower ICU and hospital mortality rate. Independent predictors for mobility level were lower age, lower Charlson Comorbidity Index, and not having received renal replacement therapy.
Conclusion: Patients' mobility level was low at ICU admission; however, most patients improved their mobility level during ICU stay. Risk factors associated with the mobility level were age, comorbidities, and use of renal replacement therapy.
Competing Interests: The authors have declared that no competing interests exist.