Urinary cotinine cut-off concentrations in children under 5 years for assessing environmental tobacco smoke exposure: a systematic review and meta-analysis protocol
Bibliographic record
Abstract
INTRODUCTION: Environmental tobacco smoke (ETS) is generally known as secondhand smoke. Assessing the magnitude of children's exposure to ETS from early infancy is essential for public health and research endeavours. Urinary cotinine is now widely recognised as the primary indicator for assessing exposure to ETS across all age groups. This systematic review and meta-analysis aim to synthesise all the published evidence on the urinary cotinine cut-off concentrations used to categorise children under 5 years as being exposed to ETS. METHODS AND ANALYSIS: We will conduct a systematic review according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses. A comprehensive search will be conducted from various databases including PubMed, EMBASE, Scopus and Cochrane Library. This search will be performed from the earliest published articles up to the latest available studies until February 2025. We will include all the experimental and observational studies, such as cohort, case-control and cross-sectional, that measure urinary cotinine concentrations in children under 5 years old. Data extraction will be conducted using a standardised data extraction form, and the study quality will be evaluated according to the guidelines specified by the Newcastle-Ottawa Scale. The extracted data will be pooled and combined for meta-analysis. Two reviewers will independently screen, select and assess the quality of the included study. The result will be tabulated in a table of characteristics of the included study, which consists of the cut-off cotinine concentrations, analytical technique, method referred, study design, study area and respondents' characteristics. ETHICS AND DISSEMINATION: Ethics approval is not required as this is a review of collected published data. Findings will be disseminated in peer-reviewed publications and conference presentations, as well as with key stakeholders, health policymakers and healthcare professionals. PROSPERO REGISTRATION NUMBER: CRD42024556969.
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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 | 0.061 | 0.084 |
| Meta-epidemiology (narrow) | 0.006 | 0.005 |
| Meta-epidemiology (broad) | 0.025 | 0.029 |
| Bibliometrics | 0.013 | 0.010 |
| Science and technology studies | 0.003 | 0.004 |
| Scholarly communication | 0.007 | 0.007 |
| Open science | 0.006 | 0.005 |
| Research integrity | 0.008 | 0.005 |
| Insufficient payload (model declined to judge) | 0.063 | 0.007 |
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".