Crude and adjusted odds ratios for the associations between serum 25-hydroxyvitamin D (25(OH)D) levels and impaired lung function or development of impaired lung function and stratified by smoking status in a random sample of Norwegian adults, the Nord-Trøndelag Health (HUNT) Study, 1996–1997 to 2006–2008
| Cross-sectional study FEV1/FVC ratio <70% | Follow-up study FEV1/FVC ratio <70% | |||||
| n (%) | Crude | Adjusted | n (%) | Crude | Adjusted | |
| Subjects n | 1220 | 869 | ||||
| Overall | 1220 | 816¶ | ||||
| 25(OH)D <50.0 nmol·L−1# | 487 (40) | 0.9 (0.6–1.5) | 1.0 (0.6–1.6) | 342 (42) | 1.9 (1.0–3.3) | 2.2 (1.2–4.2) |
| Each 25-nmol·L−1 reduction | 1.2 (0.9–1.6) | 1.3 (1.0–1.8) | 1.6 (1.1–2.3) | 1.8 (1.2–2.7) | ||
| Never-smokers | 525 | 352¶ | ||||
| 25(OH)D <50.0 nmol·L−1# | 185 (35) | 0.4 (0.2–1.2) | 0.5 (0.2–1.5) | 135 (38) | 1.3 (0.3–4.9) | 0.9 (0.2–3.9) |
| Each 25-nmol·L−1 reduction | 0.9 (0.6–1.4) | 1.1 (0.6–1.8) | 1.0 (0.5–2.2) | 0.7 (0.3–1.8) | ||
| Ever-smokers | 464¶ | |||||
| 25(OH)D <50.0 nmol·L−1# | 695 | 1.2 (0.7–2.1) | 1.2 (0.6–2.2) | 207 (45) | 1.9 (1.0–3.7) | 2.4 (1.2–4.9) |
| Each 25-nmol·L−1 reduction | 302 (43) | 1.4 (1.0–1.9) | 1.4 (1.0–2.0) | 1.7 (1.1–2.6) | 1.9 (1.2–3.0) | |
Data are presented as OR (95% CI), unless otherwise stated. Logistic regression models for forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <70% adjusted for body mass index, socioeconomic status, season, physical activity, age, sex and height. Model for overall study population adjusted for smoking status. #: reference category was serum 25(OH)D level ≥50 nmol·L−1; ¶: subjects with FEV1/FVC ratio <70% at baseline were excluded from the longitudinal analysis.