Table 2.

Associations of age, race, BMI, and month of blood sample with plasma vitamin D concentration: SELECT

Unadjusted vitamin D concentrationsAdjusted vitamin D concentrationsa
Mean (SD)Pb<37.5 N (%)c37.5–<50 N (%)cMean (SD)Pb<37.5 N (%)c37.5–<50 N (%)c
Total69.2 (29.7)635 (13.4)697 (14.7)69.2 (28.8)578 (12.2)697 (14.7)
Age, y<0.001<0.001
 50–5446.6 (25.2)72 (43.6)36 (21.8)65.5 (24.6)10 (6.1)30 (18.2)
 55–5966.1 (28.9)202 (15.9)210 (16.5)66.5 (25.4)125 (9.8)234 (18.4)
 60–6470.6 (29.6)161 (11.5)209 (15)69.9 (27.6)126 (9)206 (14.8)
 65–6971.2 (29.1)125 (11.4)140 (12.7)70.1 (26.7)92 (8.4)167 (15.2)
 ≥7073.8 (30)75 (9.3)102 (12.7)71.9 (28.4)66 (8.2)100 (12.5)
Race
 White74.4 (28.3)249 (7.2)434 (12.5)73.9 (27.1)204 (5.9)441 (12.7)
 African American50.3 (25.3)<0.001349 (35)234 (23.4)52.5 (24.6)<0.001290 (29.1)244 (24.4)
 Other/unknown72 (33.3)0.02537 (13.8)29 (10.8)71.2 (31.9)0.01534 (12.7)28 (10.4)
BMI, kg/m2<0.001<0.001
 <2575.5 (31.7)99 (10.8)104 (11.4)74.4 (29.7)74 (8.1)119 (13)
 25–<3070.8 (29.8)250 (10.9)331 (14.5)70.4 (27.1)177 (7.7)363 (15.9)
 ≥3063.1 (27.1)286 (18.6)262 (17.1)64.3 (24.6)168 (10.9)295 (19.2)
Month of blood draw<0.001<0.001
 January65.3 (30)76 (18.6)60 (14.7)64.8 (28.3)64 (15.6)77 (18.8)
 February59.1 (27.3)85 (20.8)89 (21.8)59.4 (26.1)81 (19.9)74 (18.1)
 March62.3 (27.2)79 (18.8)75 (17.8)63.1 (25.4)65 (15.4)76 (18.1)
 April63.2 (26.2)67 (17)72 (18.2)63.3 (25.3)56 (14.2)71 (18)
 May65.7 (28.2)68 (17.2)60 (15.2)66.9 (25.5)40 (10.1)62 (15.7)
 June71 (27.3)46 (9.7)68 (14.3)71.4 (24.7)20 (4.2)72 (15.2)
 July74.8 (27.1)18 (8)23 (10.3)76.8 (24.4)10 (4.5)18 (8)
 August83.9 (28.3)6 (2.5)19 (8.1)82.8 (27.5)8 (3.4)12 (5.1)
 September80.6 (33)18 (5.4)40 (12)79.4 (30.7)15 (4.5)29 (8.7)
 October77.1 (30.2)37 (7)59 (11.2)76 (28.2)27 (5.1)57 (10.8)
 November71.3 (32.1)69 (13.4)69 (13.4)70.7 (29.9)55 (10.7)82 (15.9)
 December63.8 (27)66 (16.8)63 (16)64.1 (24.5)50 (12.7)64 (16.3)
  • aVitamin D values are mutually adjusted for all other variables in table before calculating categories, except for the “Total” row, which is adjusted for month only.

  • bP values are for trend, except for race, where values are for contrast with White.

  • cAll percentages are row percentages, except for the “Total” row, which is percentage of total.