Measurements

A 7-category ordinal scale was used for evaluation of short-term outcomes as previously described (19) as follows: Category 7, death; Category 6, intensive care unit (ICU) hospitalization and requiring invasive mechanical ventilation; Category 5, ICU hospitalization and not requiring invasive mechanical ventilation; Category 4, non-ICU hospitalization and requiring supplemental oxygen; Category 3, non-ICU hospitalization and not requiring supplemental oxygen; Category 2, not hospitalized but unable to resume normal activities; and Category 1, not hospitalized with the resumption of normal activities (19). The primary outcome was the clinical improvement defined as a decline of two categories from admission on the 7-category ordinal scale on Days 7, 14, 21, and 28, respectively. Secondary outcomes included worsening (an increase of one category), need for hospitalization, supplemental oxygen, and intensive care, respectively.