Table 1.
Descriptive characteristics and differences in the study population at 31 (1997) and 46 years (2012–2013) by 25(OH)D cutoffs in nmol/L
| 31 years (n = 3541–3650) |
46 years (n = 3462–3650) |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| < 30 | 30–50 | 50–75 | > 75 | P | < 30 | 30–50 | 50–75 | > 75 | P | |
| Femalesa, % (n) | 60.7 (210) | 55.3 (671) | 56.7 (897) | 54.0 (276) | 0.23 | 51.1 (47) | 55.2 (422) | 55.9 (972) | 57.9 (610) | 0.445 |
| Marital statusa, % (n) | 0.97 | 0.016 | ||||||||
| Married | 75.4 (258) | 75.1 (903) | 75.0 (1,176) | 74.1 (375) | 73.3 (63) | 75.3 (545) | 79.4 (1,319) | 81.0 (825) | ||
| Unmarried | 24.6 (84) | 24.9 (300) | 25.0 (391) | 25.9 (131) | 26.7 (23) | 24.7 (202) | 20.6 (343) | 19.0 (193) | ||
| Occupational statusa, % (n) | 0.03 | 0.27 | ||||||||
| Higher level employee | 18.2 (59) | 21.8 (258) | 17.0 (261) | 16.7 (83) | 10.7 (9) | 18.2 (131) | 17.9 (295) | 18.2 (184) | ||
| Lower level employee/entrepreneur | 41.2 (134) | 40.2 (475) | 41.6 (640) | 41.0 (204) | 31.0 (26) | 29.0 (209) | 28.3 (467) | 27.9 (282) | ||
| Manual worker/farmer | 30.2 (98) | 27.1 (321) | 27.4 (421) | 28.1 (140) | 52.4 (44) | 46.0 (332) | 49.6 (819) | 48.8 (493) | ||
| Not working | 10.5 (34) | 10.9 (129) | 14.0 (215) | 14.3 (71) | 6.0 (5) | 6.8 (49) | 4.2 (70) | 5.1 (52) | ||
| BMIb, kg/m2 | 24.6 ± 4.2 | 24.5 ± 4.0 | 24.6 ± 4.2 | 23.9 ± 3.4 | 0.013 | 27.9 ± 5.4 | 28.2 ± 5.5 | 26.8 ± 4.7 | 25.8 ± 4.2 | < 0.001 |
| Physical activityb,c, MET hours/week, median (IQR) | 10.2 (13.4) | 10.9 (15.8) | 11.9 (17.7) | 12.9 (19.7) | 0.007 | 10.1 (21.9) | 11.9 (16.5) | 13.1 (16.8) | 15.6 (18.8) | < 0.001 |
| Smokinga, % (n) | 0.84 | < 0.001 | ||||||||
| Non-smoker | 49.1 (168) | 50.3 (601) | 47.4 (740) | 49.5 (251) | 43.0 (37) | 53.9 (387) | 55.4 (914) | 54.9 (554) | ||
| Former smoker | 26.3 (90) | 25.3 (302) | 27.5 (430) | 26.4 (134) | 20.9 (18) | 25.8 (185) | 26.9 (444) | 29.6 (299) | ||
| Current smoker | 24.6 (84) | 24.5 (293) | 25.1 (392) | 24.1 (122) | 36.0 (31) | 20.3 (146) | 17.6 (291) | 15.5 (156) | ||
| Alcohol consumptiona,d, % (n) | 0.015 | < 0.001 | ||||||||
| Abstainer | 11.9 (40) | 11.4 (134) | 9.2 (140) | 6.2 (31) | 12.8 (11) | 12.0 (87) | 10.9 (182) | 8.3 (85) | ||
| Low-risk drinker | 83.8 (280) | 84.5 (996) | 85.6 (1,306) | 87.8 (441) | 68.6 (59) | 78.4 (569) | 82.1 (1,366) | 85.0 (870) | ||
| High-risk drinker | 4.2 (14) | 4.2 (49) | 5.2 (80) | 6.0 (30) | 18.6 (16) | 9.6 (70) | 7.0 (116) | 6.7 (69) | ||
| Season of the blood samplinga,e, % (n) | < 0.001 | < 0.001 | ||||||||
| High VitD season | 24.9 (86) | 39.5 (475) | 77.5 (1,216) | 89.0 (455) | 13.0 (12) | 26.3 (201) | 44.7 (778) | 51.4 (541) | ||
| Low VitD season | 75.0 (260) | 60.5 (728) | 22.5 (354) | 11.0 (56) | 86.2 (81) | 73.7 (564) | 55.3 (962) | 48.6 (512) | ||
| Latitudea,f, % (n) | < 0.001 | < 0.001 | ||||||||
| 60 °N | 16.5 (57) | 20.5 (249) | 12.7 (201) | 7.6 (39) | 17.4 (16) | 15.4 (118) | 18.7 (325) | 24.0 (253) | ||
| 65 °N | 16.5 (57) | 20.1 (244) | 21.0 (332) | 24.5 (125) | 27.2 (25) | 32.5 (249) | 28.5 (496) | 26.4 (278) | ||
| ≥ 65 °N | 67.0 (232) | 59.3 (719) | 66.3 (1,048) | 67.8 (346) | 55.4 (51) | 52.0 (398) | 52.8 (919) | 49.6 (522) | ||
Values are displayed as percentages with numbers in parentheses as % (n) or mean (SD), unless otherwise indicated
MET metabolic equivalent of task
aDifferences between the groups were tested using Pearson’s Chi-squared test for categorical variables
bDifferences between the groups were tested using one-way analysis of variance for normally distributed and the Kruskal–Wallis test for non-parametric continuous variables
cThe MET physical activity scores in hours per week (frequency and duration of leisure time activities)
dAlcohol intake: abstainer (0 g/d), low-risk drinker (males ≤ 40 g/d, females ≤ 20 g/d), and high-risk drinker (males > 40 g/d, females > 20 g/d)
eHigh VitD season: summer (1 June–30 August) and autumn (1 September–31 October). Low vitamin D season: winter (1 November–31 March) and spring (1 April–31 May)
fLatitude: 60°N, Helsinki and surrounding areas; 65°N, the city of Oulu; > 65°N, the northernmost provinces of Oulu and Lapland