Table 3.
Vitamin D concentrations in the study population by survey year and according to sex and age, 1986–2014
| Survey year | |||||||
|---|---|---|---|---|---|---|---|
| Vitamin D concentration (ng/mL) | 1986 | 1990 | 1994 | 1999 | 2004 | 2009 | 2014 |
| Men (n = 5459) | |||||||
| Standardized mean valuea | 18.1 | 20.5 | 20.8 | 18.9 | 16.6 | 18.6 | 19.5 |
| Adjusted mean difference (95% CI)b | Ref. | 2.4 (1.7, 3.2) | 2.5 (1.8, 3.2) | 1.2 (0.5, 2.0) | − 2.2 (− 2.9, − 1.5) | 0.6 (− 0.1, 1.3) | 1.4 (0.7, 2.2) |
| Women (n = 5670) | |||||||
| Standardized mean valuea | 18.7 | 21.7 | 23.2 | 20.4 | 17.4 | 20.1 | 22.7 |
| Adjusted mean difference (95% CI)b | Ref. | 3.0 (2.2, 3.8) | 3.9 (3.2, 4.7) | 2.0 (1.2, 2.8) | − 1.7 (− 2.5, − 0.9) | 1.3 (0.5, 2.1) | 4.7 (3.8, 5.5) |
| Age < 35 years (n = 1959) | |||||||
| Standardized mean valuea | 18.1 | 20.9 | 22.3 | 19.4 | 17.7 | 19.0 | 20.2 |
| Adjusted mean difference (95% CI)b | Ref. | 3.2 (2.0, 4.4) | 4.5 (3.4, 5.7) | 2.0 (0.7, 3.2) | 0.0 (− 1.3, 1.3) | 1.3 (− 0.1, 2.6) | 2.5 (1.1, 3.9) |
| Age 35–44 years (n = 2303) | |||||||
| Standardized mean valuea | 18.9 | 21.1 | 20.8 | 18.6 | 15.8 | 18.2 | 20.2 |
| Adjusted mean difference (95% CI)b | Ref. | 2.3 (1.3, 3.4) | 2.0 (1.0, 3.1) | 0.5 − 0.7, 1.6) | − 2.7 (− 3.8, − 1.6) | − 0.4 (− 1.5, 0.7) | 1.7 (0.5, 2.9) |
| Age 45–54 years (n = 2481) | |||||||
| Standardized mean valuea | 19.3 | 21.0 | 21.4 | 19.4 | 15.9 | 18.8 | 20.6 |
| Adjusted mean difference (95% CI)b | Ref. | 2.1 (1.1, 3.1) | 2.3 (1.3, 3.3) | 0.7 (− 0.3, 1.8) | − 3.1 (− 4.2, − 2.1) | − 0.1 (− 1.2, 1.0) | 1.8 (0.7, 2.9) |
| Age ≥ 55 years (n = 4386) | |||||||
| Standardized mean valuea | 18.2 | 21.6 | 22.6 | 20.7 | 17.0 | 20.9 | 23.3 |
| Adjusted mean difference (95% CI)b | Ref. | 3.4 (2.3, 4.5) | 4.6 (3.6, 5.5) | 3.2 (2.2, 4.1) | − 0.9 (− 1.9, 0.0) | 2.9 (1.9, 3.8) | 5.3 (4.3, 6.2) |
CI confidence interval
aStandardized to the age (< 35, 35–44, 45–54, ≥ 55 years) and sex distribution, respectively, of the entire Swedish population in 2000
bEstimated from a linear regression model adjusted for sex, age (continuous using 4-knot restricted cubic splines, years), month of sampling (January/February, March/April), country of birth (Sweden, other), civil status (married/cohabiting, other), educational level (university, non-university), smoking status (current, non-current), and body mass index (< 25, 25–29, ≥ 30 kg/m2)