Table 4.

Subgroup analyses for the Primary and validation cohorts

A.Primary cohort subanalysis
Serum 25(OH)D < 50 nmol/L and association with hospitalization
Subgroup	OR (95% CI)	P value
Female	2.15 (1.78-2.61)	<0.005
Male	2.10 (1.75-2.52)	<0.005
Age ≥ 60 years	2.46 (2.12-2.86)	<0.005
Age < 60 years	2.68 (2.02-3.55)	<0.005
25(OH)D measured in spring/summer	2.14 (1.69-2.72)	<0.005
25(OH)D measured in autumn/winter	2.19 (1.87-2.57)	<0.005
Serum 25(OH)D < 25 nmol/L and association with hospitalization
Subgroup	OR (95% CI)	P value
Female	3.56 (2.91-4.35)	<0.005
Male	3.59 (3.00-4.28)	<0.005
Age ≥ 60 years	3.68 (3.15-4.31)	<0.005
Age < 60 years	4.11 (3.17-5.32)	<0.005
25(OH)D measured in spring/summer	4.54 (3.58-5.75)	<0.005
25(OH)D measured in autumn/winter	3.42 (2.91-4.01)	<0.005
B.Validation cohort subanalysis
Serum 25(OH)D < 50 nmol/L and association with hospitalization
Subgroup	OR (95% CI)	P value
Female	2.15 (1.70-2.72)	<0.005
Male	1.92 (1.54-2.40)	<0.005
Age ≥ 60 years	2.47 (2.06-2.97)	<0.005
Age < 60 years	2.39 (1.71-3.36)	<0.005
25(OH)D measured in spring/summer	2.30 (1.71-3.10)	<0.005
25(OH)D measured in autumn/winter	2.05 (1.69-2.48)	<0.005
Serum 25(OH)D < 25 nmol/L and association with hospitalization
Subgroup	OR (95% CI)	P value
Female	3.30 (2.62-4.16)	<0.005
Male	2.93 (2.38-3.59)	<0.005
Age ≥ 60 years	3.19 (2.67-3.82)	<0.005
Age < 60 years	3.43 (2.53-4.64)	<0.005
25(OH)D measured in spring/summer	4.28 (3.25-5.64)	<0.005
25(OH)D measured in autumn/winter	3.00 (2.50-3.61)	<0.005

Abbreviations: 25(OH)D, 25-hydroxyvitamin D; OR, odds ratio.