Vitamin D Status and Respiratory Tract Infections: A Systematic Review and Meta‐Analysis of Observational Evidence
Bibliographic record
Abstract
Background Vitamin D is postulated to have antimicrobial properties, reduce inflammation, and has been implicated in respiratory health. Serum 25‐hydroxyvitamin D (25[OH]D) has been associated with risk and severity of respiratory tract infections (RTIs) in some, but not all, observational studies. Methods We searched MEDLINE, EMBASE, CCTR, AMED, and LILACS (through August 1, 2014) to identify observational studies (with the exception of case reports). Odds ratios, dichotomizing serum 25(OH)D at 50 and 75 nmol/L, were pooled using generic inverse variance methods with random‐effects models. Heterogeneity was assessed using Cochrane's Q and quantified by the I 2 statistic. Subgroups included age, location of infection, and study design. Results We included 19 studies (n = 44, 301) in one or more meta‐analyses. Serum 25(OH)D levels < 50 nmol/L were associated with an increased odds of RTIs (OR = 2.63, 95% CI: 1.45‐4.76). Subgroup analyses revealed that the effect remained significant in children (OR = 2.80, 95% CI: 1.31‐5.96), lower RTIs (OR = 2.06, 95% CI: 1.16‐3.55), and in case‐control studies (OR = 2.25, 95% CI: 1.14‐4.45). Similar results were obtained when serum 25(OH)D was dichotomized at 75 nmol/L. Moderate heterogeneity was observed in all analyses (I 2 蠅 42%). Conclusions Low serum 25(OH)D was associated with an increased risk of RTIs and remained significant in various subgroup analyses. Future studies are required to elucidate these subgroup effects.
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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 | 0.013 | 0.034 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.018 | 0.032 |
| Bibliometrics | 0.007 | 0.009 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| 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".