REFERENCE STANDARDS FOR BOYS AND GIRLS TOTAL BODY BONE MINERAL CONTENT
Bibliographic record
Abstract
Our ability to diagnose and treat children at risk from osteoporosis remains limited, as the current reference standards are incomplete. This paper presents reference standards for total body (TB) bone mineral content (BMC). Children were drawn from the Saskatchewan Pediatric Bone Mineral Accrual Study, a longitudinal study that ran from 1991 through to 1998. Data are presented from 85 boys and 67 girls (entry age range 8 to 14 years). Factors taken into consideration included age, weight and height, sitting height and leg length; plus in girls' menarche attainment. The latter anthropometric indices were included as surrogate measures of maturation, since peak leg length velocity precedes peak height velocity, which in turn precedes peak sitting height velocity. TB BMC was measured annually for 7 consecutive years by DXA (Hologic 2000 QDR array mode analysed with software version 5.67A). Anthropometric values were measured bi-annually. Predictive equations were developed using a multilevel modelling approach, with subjects aligned on chronological age. Models were compared using the likelihood ratio statistic. In the boys' age (centred around 14 years), weight (wt), leg length (leglen), sitting height (sith), weight by height (wtbyht), leg length by sitting height (lebysit),) and the interactions of age and height (ageht) and age and weight (agewt) all had significant independent effects on TB BMC gain, in that the slope coefficients for these variables were greater than their respective standard error estimates. Boys' TB BMC = −3444.4 - 384.1* age - 3.1*age2 + 0.31* age3 + 87.4*wt - 119.2* wtbyht + 56.2*sitht −58.3*lenglen + 45.4*legbysit + 2.92*ageht - 1.35* agewt. In contrast to boys' leglen, legbysit and the interaction of agewt were not significant predictors of girls' TB BMC, however menarcheal status was (menar û 1 = yes, 0 = no). Girls' TB BMC = 137.1 - 90.5*age - 7.0*age2 - 0.48*age3 + 0.13*age4 + 49.8*wt û 60.7*wtbyht + 10.8*sitht + 0.93*ageht + 63.5*menar. The variance's at level 2 of the models were used to calculate 95% CI's for each model. These predictive equations incorporate the important determinants of TB BMC, namely somatic growth and maturation. Supported by National Health Research and Development Program
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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 | 0.015 | 0.023 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.012 | 0.008 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.006 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.010 | 0.009 |
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".