Table 3.

Unadjusted Risk Ratios for Hospitalization With an Infection and Hospitalization Without an Infection in a Cohort of Medicare Beneficiaries According to Serum 25-Hydroxyvitamin D Concentration as an Ordinal Variable (n = 1,713), United States, 2001–2004^a,b

Serum 25(OH) D Concentration, ng/mL	Hospitalization With Infection vs. No Hospitalization		Hospitalization Without Infection vs. No Hospitalization
	RR	95% CI	RR	95% CI
<10	4.8	1.7, 13.4	1.8	0.8, 4.2
10–19	1.9	1.0, 3.5	2.0	1.2, 3.2
20–29	1.3	0.7, 2.4	1.7	1.1, 2.6
≥30	1.0	Referent	1.0	Referent

Abbreviations: CI, confidence interval; 25(OH)D, 25-hydroxyvitamin D; RR, risk ratio.

^a Data from the 2001–2002 and 2003–2004 cycles of the National Health and Nutrition Examination Survey.

^b Global test of the null hypothesis—likelihood ratio test: P < 0.01; Wald test: P < 0.01.