Comment on: Less sodium and more potassium to reduce cardiovascular risk and the PURE study
Bibliographic record
Abstract
The authors response is available at https://doi.org/10.1093/ehjopen/oead097. We read with interest the commentary by Muiesan et al. but are concerned the PURE study was cited to describe the association between dietary sodium and blood pressure (BP).1 The PURE study used 24-h urine sodium estimated from a fasting morning spot urine sample and the Kawasaki equation, a method which has been shown to have a large systematic and random error in estimating 24-h urine sodium.2 Twenty-four-hour sodium estimated from the Kawasaki equation (and other estimating equations) markedly alter the association of sodium to BP relative to measured 24-h. urine sodium and have an association with BP independent of sodium values.2 The PURE study has been variably reported as showing that there is no significant association of dietary sodium with BP below 3000 mg/day, and that the association is curvilinear with less impact at lower levels of dietary sodium. Meta-analyses of randomized controlled trials (RTCs) utilizing 24-h. urine sodium samples show a linear graded association with BP at greater than 800 mg sodium/day.3 The association between sodium and BP occurs in infants, children, and the elderly and in those with normal BP and hypertension.3 Those of older age, with hypertension and Black ancestry have greater changes in BP with changes in dietary sodium.3 Spot urine samples with estimating equations have been recommended by major international and national health organizations not to be used to estimate 24-h. urine sodium in individuals especially in association with health outcomes2 The most recent recommendation clearly states ‘It is strongly recommended to not conduct, fund, or publish research studies that use spot urine samples with estimating equations to assess individuals’ sodium (salt) intake in association with health outcomes’.2 The recommendations further state ‘Manuscripts reviewing the literature on the health impacts of reducing dietary sodium that include studies that have used spot and short duration timed urine samples with estimating equations to assess individual sodium intake in association with health outcomes need to fully acknowledge the limitations of this method (i.e. that the method is recommended not to be used and that it is associated with spurious associations)’.2 The PURE study provides a good example (case study) that using an inappropriate methodology even with a large sample size can produce spurious results. Randomized controlled trial evidence should be cited to support the association of dietary sodium with BP and cardiovascular disease.3 N.R.C.C. drafted the letter, which was reviewed revised, and approved by F.J.H., R.M.M., F.P.C., and G.M.M. None.
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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 | 0.022 | 0.118 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.005 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.004 | 0.004 |
| Scholarly communication | 0.004 | 0.005 |
| Open science | 0.007 | 0.003 |
| Research integrity | 0.053 | 0.046 |
| Insufficient payload (model declined to judge) | 0.027 | 0.017 |
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".