Looking at it more closely, it looks like there's

Looking at it more closely, it looks like there's reason to believe the patients pools were similar. Of course we don't know the S/C ratio. But RLFTF excluded ECMO and LL did not.

Here's the inclusion criteria for RLFTF:
Inclusion Criteria:

Critical COVID-19 with respiratory failure
Physician determination that patient is on maximal conventional medical therapy
Exclusion Criteria:

Pregnancy (pregnant women may apply for open label treatment under compassionate care IND
Age <18 years
Mechanical ventilation for more than 7 days in primary cohort. Mechanical ventilation>21 days in the exploratory cohort
Mean Arterial Pressure < 65 mm Hg with use of pressor per ICU protocol
Irreversible condition (other than COVID-19) with projected fatal course
ECMO
Current or recent (within 30 d) enrollment in another investigational trial of anti-IL6 drug;
Active diagnosis of Acquired immune deficiency syndrome;
Transplant patients currently immunosuppressed;
Chemotherapy-induced neutropenia (granulocyte count <1000/mm3);
Cardiogenic shock; congestive heart failure - NYHA Class 3 or 4;
Recent myocardial infarction - within last 6 months and troponin > 0.5
Anuria (urine output < 50 ml/d) or other signs of multi-organ failure
Severe liver disease with portal hypertension;
Recent stroke or head trauma within last 12 months
Increased intracranial pressure, or other serious neurologic disorder;
Liquid Diarrhea more than 3x/day; defined as more than 3 non-bloody watery stools within a 24-hour period, requiring additional fluid and electrolyte supplementation