Table 2.

Clinical outcomes of the patients

Outcomes	Melatonin (n = 109)	Control (n = 117)	Difference or Odds Ratio	P-value
Primary outcome
In-hospital mortality until day 28	73/109 (67.0)	110/117 (94.0)	7.75 (3.27–18.35)	< 0.001
Invasive mechanical ventilation	56/109 (51.4)	83/117 (70.9)	2.31 (1.34–4.00)	< 0.001
Secondary outcome
Clinical status at day 7a	4.0 (4.0–4.0)	4.0 (4.0–5.0)	– 0.34 ( – 0.93–0.06)	0.014
Clinical status at day 14a	3.0 (2.0–4.0)	4.0 (3.0–5.0)	– 0.12 ( – 1.77–0.71)	< 0.001
Time to clinical improvementb	12.0 (9.0–13.0)	16.0 (10.0–19.0)	3.92 (1.69–6.14)	0.038
LOS in hospital until dischargec	15.0 (13.0–17.0)	21.0 (14.0–24.0)	5.00 (0.15–9.84)	0.026
LOS in ICUc	9.0 (6.0–10.0)	13.0 (7.0–15.0)	3.59 (1.95–5.24)	< 0.001
Ventilator-free days	15.5 (7.0–18.0)	6.0 (4.0–9.0)	6.00 (3.98–8.03)	< 0.001

Values were presented as median (IQR) for continuous variables and n (%) for categorical variables. Primary and secondary outcomes were analyzed in the intent-to-treat population (patients received at least one dose of melatonin). Comparison between groups was performed using the Mann–Whitney U test or the Fisher’s exact test. p < 0.05 was considered as statistically significant

ICU intensive care unit, LOS length of stay

^aMedian value for clinical status on the ordinal scale at day 7 and 14

^bMedian number of days until improvement by ≥ 2 on the ordinal scale in clinical status

^cMedian number of days until hospital/ICU discharge for alive patients