Table 3. 25(OH)D level stratified by COVID-19 disease severity category before and after cosinor correction models for the annual mean as well as each patient’s date of hospitalization.

		No. (%)				p value 2-sided (between groups)	p value 2-sided (severe/critical vs. mild/moderate disease)
Characteristics		COVID-19 disease severity category (WHO)
		Mild	Moderate	Severe	Critical
Pre-infection 25(OH)D level (ng/mL) evaluated 14–730 days before positive COVID-19 test
	median	34.2	18.9	11.3	10.0
	<20	7 (8.8)	50 (58.1)	64 (86.5)	12 (92.3)	p < 0.001 §	p < 0.001†
	20–29.9	8 (10)	24 (27.9)	3 (4.1)	1 (7.7)
	30–39.9	37 (46.2)	3 (3.5)	4 (5.4)	0 (0.0)
	≥40	28 (35.0)	9 (10.5)	3 (4.0)	0 (0.0)
Predicted 25(OH)D level (ng/mL) annual mean correction based on the cosinor model [Eq 1]
	median	36.2	18.1	11.1	10.9
	<20	7 (8.8)	46 (53.5)	64 (86.5)	11 (84.6)	p < 0.001 §	p < 0.001 †
	20–29.9	11 (13.8)	26 (30.2)	3 (4.1)	2 (15.4)
	30–39.9	35 (43.8)	5 (5.8)	4 (5.4)	0 (0.0)
	≥40	27 (33.8)	9 (10.5)	3 (4.1)	0 (0.0)
Predicted 25(OH)D level (ng/mL) corrected to the hospitalization date based on the cosinor model [Eq 3]
	median	36.1	19.4	13.0	11.8
	<20	6 (7.5)	52 (60.5)	63 (85.1)	11 (84.6)	p < 0.001 §	p < 0.001 †
	20–29.9	12 (15)	18 (20.9)	4 (5.4)	2 (15.4
	30–39.9	33 (41.3)	8 (9.3)	4 (5.4)	0 (0.0)
	≥40	29 (36.3)	8 (9.3)	3 (4.1)	0 (0.0)

§ P values were determined using Kruskal-Wallis Test.

† P values were determined using Mann-Whitney Test.