Positive Association Between 25-Hydroxyvitamin D and C-Reactive Protein is Confounded by Hormonal Contraceptive Use
Bibliographic record
Abstract
BACKGROUND: Studies of the relationship between vitamin D and inflammation are equivocal. This may be due to unaccounted confounding. Hormonal contraceptive (HC) use is associated with elevated circulating 25-hydroxyvitamin D [25(OH)D] in Caucasians and African-Americans, but its effects on 25(OH)D in other ethnicities are unclear. HC use is associated with elevated C-reactive protein (CRP), an inflammatory biomarker. Our objectives were to assess the effect of HC use on 25(OH)D across ethnic groups, and to examine the association between HC, 25(OH)D and CRP in an ethnically diverse population of young adults. METHODS: We recruited Caucasian, East Asian, and South Asian individuals (n=1,403) from Toronto, Canada. Fasting blood measures of 25(OH)D and CRP were obtained. RESULTS: Across ethnic groups, women HC users (n=280) had higher 25(OH)D and CRP than women HC non-users (n=695) and men (n=428) (p<0.008 and p<0.0001, respectively). Circulating 25(OH)D was positively associated with CRP in the entire population in models not accounting for HC use (β=0.010±0.003; p<0.0001). There was no association when men and women HC non-users were examined separately. Among women HC users, there was no association after accounting for hormone dose. A positive association between 25(OH)D and CRP among individuals above the median 25(OH)D (≥51.9 nmol/L) was not significant after adjustment for HC use. No association was observed among individuals below the median. CONCLUSIONS: HC use and 25(OH)D were positively associated across ethnic groups. We found no association between 25(OH)D and CRP when HC use was accounted for. HC use confounds the association between 25(OH)D and CRP.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.012 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".