Effect of heated mittens on physical hand function in people with hand osteoarthritis: randomised controlled trial.
Bartholdy C, Døssing A, Stisen ZR, Nielsen SM, Christensen R, Danneskiold-Samsøe B, Bliddal H, Henriksen M, Ellegaard K
- DOI
- 10.1136/bmj-2023-078222
- Record issued
- 2026-08-16
- Engine
- 7.39.0
- Exported
- 2026-09-22
Prepared by Alpha1. This document is confidential: it is intended for the recipient it was shared with and must not be redistributed. The live record at alpha1science.com/verify/41f80e39-1875-4933-854a-84898c24e7e6 is authoritative.
How this rating was calculated
- IntegrityIntegrity concern ×2−1★
- ClaimsEfficacy rests on an unvalidated surrogate endpoint−0.5★
- ClaimsTreatment effect not shown to be clinically meaningful−0.5★
- ReportingData & code availability partially met−0.25★
- The numeric-impossibility checks (GRIM/GRIMMER/DEBIT/SPRITE) did not run: 15 reported means were read, and their group size is not stated where the values are printed (this source has no machine-readable table structure). These checks need the count the mean was averaged over, so none was performed.
- No data or code availability links were detected to verify.
- 01Efficacy rests on an unvalidated surrogate endpoint
The primary outcome is the AUSCAN function subscale, a patient-reported measure of physical function, which is a surrogate for clinical benefit. The paper does not provide evidence of target engagement at the tested dose (e.g., skin temperature measurements) nor does it cite validated evidence linking changes in AUSCAN function to hard clinical outcomes. The minimal clinically important difference is not established, and the observed difference of 3.0 points is below the estimated 8-point target used for powering.
“The primary outcome was change in hand function measured on the function subscale of the Australian/Canadian hand osteoarthritis index (AUSCAN; score 0-100 points) at six weeks.”
- 02Treatment effect not shown to be clinically meaningful
The primary outcome showed a between-group difference of 3.0 points (95% CI -0.4 to 6.3; P=0.09), which was not statistically significant and is below the minimal clinically important difference of 4 points for within-group changes and the 8-point target used for powering. The paper itself notes the trial may have been underpowered for small but potentially clinically relevant differences.
“The between group difference for change in AUSCAN function at week 6 was 3.0 points (95% confidence interval (CI) −0.4 to 6.3; P=0.09) in favour of heated mittens.”
This Kaimen Rigor review uses Kaimen Rigor reviewers trained on a curated corpus of high-fidelity and retracted papers, with expert supervision and curation. It can still make mistakes; verify each finding against the source before relying on it.
This is a well-conducted and well-reported randomized controlled trial with rigorous design, clear ethical approvals, and appropriate statistical methods. The main weakness is the vague data availability statement, which lacks a concrete access mechanism, and a few minor copyedit issues including an inverted confidence interval and a percentage typo in Table 1.
Both reviewers agreed on all dimensions and study type (interventional RCT); no divergence to reconcile. The statistics verification covered only 1 test (limited coverage), so most statistical results remain unverified but not flagged as problematic. The copyedit pass flagged minor issues, and the integrity check noted two internal contradictions (inverted CI and Table 1 percentage) that are likely typographical.
Numerical inconsistencies
1 finding · worst lowValues that contradict each other or are impossible for the stated sample: recomputed p-values and test statistics, GRIM/GRIMMER checks on summary numbers, percentages against their own counts, totals against their parts, and estimates against their own confidence intervals.
- Internal contradictions in the reported numbersAssessed
Recomputed 1 test: 1 consistent, 0 inconsistent; 1 via agent-written checks.
- CONSISTENTreported p = .090 · recomputed p = .079Reviewers 1, 2Primary outcome between-group difference p-value from CI
“The mean between group difference was 3.0 points (95% CI −0.4 to 6.3; P=0.09)”
Taken as given: The CI is a 95% confidence interval for the difference in means.; The estimate is the difference in means (3.0).; The CI is symmetric on the linear scale (not log).Method: Recomputed two-sided p-value from the estimate and 95% CI using the normal approximation.How we recomputed it: pCI(3.0, -0.4, 6.3, 0)
- lowinternal contradictionThe confidence interval for the difference in self-reported mitten use days is reported as (95% CI 2.5 to 3.8) with a point estimate of 1 day, which is inconsistent (the CI does not contain the point estimate).
“with a group difference in self-reported mittens use of 1 day (95% CI 2.5 to 3.8 days)”
ResultsFind in source - lowinternal contradictionIn Table 1, the percentage for 'Other' analgesics in the control group is reported as 20%, but the count is 8 out of 100, which would be 8%. This appears to be a typographical error.
“Other | 9 (9) | 8 (20) | 17 (8.5)”
Table 1Find in source
Overstated conclusions
2 findings · worst highConclusions that reach past what the paper's own results support — including a significance claim that no longer holds when the statistic is recomputed, and efficacy resting on an unvalidated surrogate endpoint.
- Efficacy rests on an unvalidated surrogate endpointAssessed
- Treatment effect not shown to be clinically meaningfulAssessed
3 major claims checked against the paper's own evidence: all adequately supported.
- supportedReviewers 1, 2Use of electrically heated mittens for six weeks was not related to a positive change in physical hand function compared with control mittens.The primary outcome showed no statistically significant difference (P=0.09), supporting the claim of no positive change.Evidence: Primary outcome between-group difference: 3.0 points (95% CI −0.4 to 6.3; P=0.09).
“Use of electrically heated mittens for six weeks was not related to a positive change in physical hand function compared with control mittens.”
ConclusionFind in source - supportedReviewers 1, 2Heated mittens provided no additional benefits on global rating of hand osteoarthritis related problems and grip strength.The between-group differences for these outcomes were not statistically significant, with CIs crossing zero.Evidence: Global rating difference: 2.8 points (95% CI −3.7 to 9.2); grip strength right hand: 2.3 newtons (95% CI −16.3 to 21.0).
“Heated mittens provided no additional benefits on global rating of hand osteoarthritis related problems and grip strength.”
ConclusionFind in source - supportedReviewers 1, 2A small benefit was detected for hand pain, but this could have been overestimated.The secondary outcome for pain showed a statistically significant difference, but the authors acknowledge the risk of overestimation due to unsuccessful masking.Evidence: AUSCAN pain difference: 5.9 points (95% CI 2.2 to 9.5).
“A small benefit was detected for hand pain, but this could have been overestimated.”
ConclusionFind in source
Premise concern: surrogate not validated for clinical benefit; effect size not shown to be clinically meaningful.
- INADEQUATESurrogate endpointThe primary outcome is the AUSCAN function subscale, a patient-reported measure of physical function, which is a surrogate for clinical benefit. The paper does not provide evidence of target engagement at the tested dose (e.g., skin temperature measurements) nor does it cite validated evidence linking changes in AUSCAN function to hard clinical outcomes. The minimal clinically important difference is not established, and the observed difference of 3.0 points is below the estimated 8-point target used for powering.
“The primary outcome was change in hand function measured on the function subscale of the Australian/Canadian hand osteoarthritis index (AUSCAN; score 0-100 points) at six weeks.”
- INADEQUATEEffect sizeThe primary outcome showed a between-group difference of 3.0 points (95% CI -0.4 to 6.3; P=0.09), which was not statistically significant and is below the minimal clinically important difference of 4 points for within-group changes and the 8-point target used for powering. The paper itself notes the trial may have been underpowered for small but potentially clinically relevant differences.
“The between group difference for change in AUSCAN function at week 6 was 3.0 points (95% confidence interval (CI) −0.4 to 6.3; P=0.09) in favour of heated mittens.”
Data authenticity concerns
None foundAn adversarial read for patterns associated with data that may not be genuine: results that look too clean, implausibly large effects, duplicated data or images, and methods that do not match the results reported.
Checked — nothing surfaced.
Reporting gaps
1 finding · worst mediumRequired detail the manuscript never states — study design, biological variables, ethics approval and consent, key resources, statistical reporting, data and code availability, and overall transparency.
- Data/code availability incompleteAssessed
The paper cites prior research on heat therapy and systematic reviews, acknowledges the low quality of underlying trials, and notes the lack of consensus. It clearly links the premise to the study objective and states a hypothesis. Limitations of prior research are addressed by noting the need for higher-quality trials and the practical advantages of mittens.
“Systematic reviews looked at the effect of these treatments, with the overall conclusion that a symptom moderating effect was possible.”
“We hypothesised that wearing heated mittens would result in greater improvement in hand function and relief of symptoms than wearing control mittens in people with hand osteoarthritis.”
“The recommendation was conditional based on the limited number and low methodological quality of the underlying randomised controlled trials.”
“Systematic reviews looked at the effect of these treatments, with the overall conclusion that a symptom moderating effect was possible.”
“The recommendation was conditional based on the limited number and low methodological quality of the underlying randomised controlled trials.”
“The use of heated mittens as a symptom moderation tool to treat hand osteoarthritis has never been tested.”
Randomization used permuted random blocks of variable sizes, with allocation concealment via a masked third party. Blinding was attempted but not successful, which is acknowledged. A priori sample size calculation is provided. Inclusion/exclusion criteria are described, and the analysis populations (ITT and per-protocol) are defined. Missing data handling is specified. The trial is a single pivotal trial, so independent replication is not applicable.
“we randomised participants in a 1:1 ratio based on permuted random blocks of variable sizes (2-6 in each block) generated before enrolment.”
“180 participants providing 80.2% power to detect an 8 point mean difference in AUSCAN function scores.”
“we randomised participants in a 1:1 ratio based on permuted random blocks of variable sizes (2-6 in each block) generated before enrolment.”
“The mittens were coded A or B to conceal the allocation from participants, clinical and non-clinical staff, and outcome assessors.”
“180 participants providing 80.2% power to detect an 8 point mean difference in AUSCAN function scores.”
The study reports age, sex, BMI, and disease duration in the results and baseline table. Since both sexes are enrolled, sex justification is not applicable. Species/strain and housing conditions are not applicable for a human trial.
“87% (n=173) were women”
“Median disease duration was 10 years (interquartile range 5-15 years).”
“87% (n=173) were women”
“Median disease duration was 10 years (interquartile range 5-15 years).”
The paper states that the project was deemed exempt from approval by the local Health Research Ethics Committee (ref: 20020569) and approved by the Danish Data Security Agency (ref: P-2020-670). Informed consent is mentioned in the Methods. Regulatory compliance is implied through adherence to Danish regulations.
“This project was deemed exempt from approval by the local Health Research Ethics Committee (ref: 20020569) and did not require approval from the Danish Medical Equipment Board (ref: 2020030890).”
“All participants provided signed informed consent before trial participation.”
“The project was approved by the Danish Data Security Agency before the patients first visit (ref: P-2020-670).”
“This project was deemed exempt from approval by the local Health Research Ethics Committee (ref: 20020569)”
“All participants provided signed informed consent before trial participation.”
“The project was approved by the Danish Data Security Agency before the patients first visit (ref: P-2020-670).”
The mittens are identified as commercially available from Nordic Heat, Denmark, with a description of the heating element and control mechanism. The statistical software (R and SAS) is identified. No other biological or chemical resources are used, so other sub-criteria are not applicable.
“The mittens used in this trial are commercially available (Nordic Heat, Denmark).”
“The statistical analysis was performed using R (version 4.0.3) and SAS studio.”
“The mittens used in this trial are commercially available (Nordic Heat, Denmark).”
“bilateral measures of grip strength using a dynamometer (Grippit; Detektor, Gothenburg, Sweden)”
“The statistical analysis was performed using R (version 4.0.3) and SAS studio.”
The primary analysis uses mixed linear models with adjustment for baseline, and secondary outcomes use ANCOVA with multiple imputation. Effect sizes with 95% CIs are reported for all outcomes. Exact p-values are given for the primary outcome; secondary outcomes are reported with CIs only, which is acceptable. Software is identified. Data presentation includes per-group n and appropriate figures. Mathematical plausibility checks were not possible for all values, but no obvious errors were found.
“The mean between group difference was 3.0 points (95% CI −0.4 to 6.3; P=0.09)”
“The statistical analysis was performed using R (version 4.0.3) and SAS studio.”
“Continuous outcomes with repeated measures (ie, AUSCAN pain, function, and stiffness subscales) were analysed using repeated measures mixed linear models”
“The mean between group difference was 3.0 points (95% CI −0.4 to 6.3; P=0.09)”
“The statistical analysis was performed using R (version 4.0.3) and SAS studio.”
The data availability statement is present but does not specify a repository, platform, or conditions for access. It only provides an email address. Since the trial involves patient data, repository deposit and accession numbers are not applicable. No custom code is mentioned, so code sharing is not applicable.
“Data will be made available upon reasonable request to the corresponding author at cecilie.bartholdy.skjaldgaard@regionh.dk.”
“Data will be made available upon reasonable request to the corresponding author at cecilie.bartholdy.skjaldgaard@regionh.dk.”
The trial is registered at ClinicalTrials.gov (NCT04576403). Methods are comprehensive. Limitations are thoroughly discussed, including unsuccessful masking and potential underpowering. Conclusions are proportional to the evidence. Funding sources and competing interests are declared. No reporting guideline is explicitly mentioned, but the paper follows CONSORT-like structure.
“Trial registration ClinicalTrials.gov NCT04576403”
“It was not possible to mask the participants throughout the trial, which is a major limitation.”
“Funding: This trial was supported by the Danish Rheumatism Association (R192-A6735), Bispebjerg and Frederiksberg Hospital research foundation, A.P. Møllers fond (L-2021-00234).”
“Trial registration ClinicalTrials.gov NCT04576403”
“It was not possible to mask the participants throughout the trial, which is a major limitation.”
“This trial was supported by the Danish Rheumatism Association (R192-A6735), Bispebjerg and Frederiksberg Hospital research foundation, A.P. Møllers fond (L-2021-00234).”
Registered (1 ID: ClinicalTrials.gov). No reporting guideline cited.
Broken references and links
None found · partly checkedReferences checked against Crossref, OpenAlex and Retraction Watch for retractions and resolvability, plus declared data and code links probed for whether they resolve to content matching the paper.
Nothing surfaced — but not everything feeding this category ran (missing: data/code link verification), so read this as a partial clean bill.
Checked 47 references by DOI: 46 verified — 1 no DOI (shown, not verified).
- NO DOIEULAR Handbook of Clinical Assessments in Rheumatoid Arthritis: On Behalf of the EULAR Standing Committee for International Clinical Studies Including Therapeutic Trials-ESCISITNo DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
Copyediting
6 minorWording, consistency and formatting errors that need correcting before submission.
No major wording or formatting errors. 6 minor suggestions below.
6 copyedit issues flagged: mostly typo, consistency, grammar.
- MINORtypoResults, Adherence“with a group difference in self-reported mittens use of 1 day (95% CI 2.5 to 3.8 days)”→ The confidence interval appears to be inverted; likely should be -2.5 to 3.8 or similar.The CI lower bound is higher than the point estimate, which is unusual.
- MINORconsistencyTable 1, Type of analgesic“Other | 9 (9) | 8 (20) | 17 (8.5)”→ The percentage for control group 'Other' appears to be 20%, but should be 8% (8/100).Likely a typographical error in the percentage.
- MINORgrammarMethods, Outcome measures“The questionnaire is copyrighted, but further information is available at www.womac.com (http://www.womac.com) .”→ Remove extra space before the period.Minor formatting issue.
- MINORtypoAbstract, Results“The between group difference for change in AUSCAN function at week 6 was 3.0 points”→ Consider hyphenating 'between-group' for consistency.Minor style issue.
- MINORconsistencyTable 1, Type of analgesic“Other | 9 (9) | 8 (20) | 17 (8.5)”→ The percentage for 'Other' in the control group appears to be 20%, which may be a typo; should it be 8%?Potential inconsistency in reported percentage.
- MINORgrammarMethods, Statistical analysis“The statistical analysis was performed using R (version 4.0.3) and SAS studio.”→ Change 'SAS studio' to 'SAS Studio' for proper capitalization.Minor capitalization issue.
The published work is methodologically robust and generally trustworthy, but readers should weigh the vague data availability statement and the minor internal inconsistencies (inverted CI, Table 1 percentage) as reporting flaws that could warrant a correction or clarification. The primary outcome was null (P=0.09), and conclusions are appropriately proportional, so no major validity threat is apparent.
- 1.HIGHcopyeditCorrect the inverted confidence interval in Results, Adherence: the reported '1 day (95% CI 2.5 to 3.8 days)' is impossible because the CI does not contain the point estimate; verify the actual values and fix.An impossible confidence interval is a demonstrable internal contradiction that undermines the credibility of the reported result and could warrant a correction.
- 2.HIGHcopyeditFix the percentage for 'Other' analgesics in Table 1 control group: 8 out of 100 should be 8%, not 20%.A percentage that does not match the count is a factual error in a key table that readers will notice and could raise questions about data accuracy.
- 3.HIGHdata codeEnhance the Data availability statement to specify a concrete access mechanism, such as a data repository or a data access committee, with conditions and timeframe, rather than just an email address.The current 'upon reasonable request' statement is vague and does not meet modern transparency expectations for clinical trial data sharing.
- 4.MEDIUMdata codeConsider depositing de-identified participant data in a recognized repository (e.g., Dryad, Zenodo) or provide a detailed data sharing plan in the protocol.Repository deposit would make the data availability statement actionable and improve reproducibility.
- 5.MEDIUMreportingExplicitly mention adherence to CONSORT guidelines in the Methods or supplement, and provide the CONSORT checklist as supplementary material.Explicit reporting guideline adherence enhances transparency and is expected for RCTs.
- 6.MEDIUMdata codeIf custom analysis code was used, share it in a public repository (e.g., GitHub) with a DOI to improve reproducibility.Sharing analysis code allows independent verification of the statistical methods.
- 7.MEDIUMstatisticsProvide exact p-values for all secondary outcomes, or clarify that they are reported with confidence intervals only by design.Exact p-values for secondary outcomes would improve transparency, though reporting CIs alone is acceptable.
- 8.MEDIUMreportingReport the minimal clinically important difference (MCID) for the primary outcome (AUSCAN function) to aid interpretation of the null result.Contextualizing the 3.0-point difference against an MCID helps readers judge clinical relevance.
- 9.LOWcopyeditRemove the extra space before the period in Methods, Outcome measures: 'www.womac.com (http://www.womac.com) .'Minor formatting issue that should be cleaned up.
- 10.LOWcopyeditHyphenate 'between-group' in the Abstract and throughout for consistency.Consistent terminology improves readability.
- 11.LOWcopyeditChange 'SAS studio' to 'SAS Studio' in Methods, Statistical analysis for proper capitalization.Minor capitalization issue.
- 12.LOWreportingIn the limitations, discuss the potential impact of unsuccessful masking on the primary outcome more explicitly.The acknowledged masking failure could bias the primary outcome, and its potential impact should be addressed.
The star rating is the report’s one-glance summary. Every paper starts at 5★ and loses stars for the concrete problems the review finds — so a rating is never a vague average, it’s a running total you can read line by line under “How this rating was calculated.”
- Reporting — 8 dimensionseach dimension that fully fails−½★
- each dimension partially met−¼★
- Statistics · Integrity · Claimseach serious problem−1★
- each medium problem−½★
- Citationseach retracted or unverifiable reference−¼★
- Copyeditonly when the manuscript needs a full edit−½★
The rating never drops below 1★, and a demonstrable critical failure (an impossible statistic, a proven ethics violation) caps it at 1★ on its own — so the stars can never look healthy when the verdict is CRITICAL.
The rating draws on a panel of agents. Three independent Kaimen Rigor reviewers grade the eight dimensions below across several independent passes (the shown verdict is their majority vote — steadier than any single run), isolate the paper’s major claims and check its own evidence backs them, and flag integrity concerns. Alongside them, a citation agent resolves every reference against Crossref, OpenAlex, and Retraction Watch; a statistics agent recomputes reported tests; and rule-based checks verify that declared data/code links actually resolve. Full text is required — an abstract-only submission is not analyzed.
Graded against NIH, MDAR, ARRIVE 2.0, CONSORT, EQUATOR, and RRID guidelines. A dimension that doesn’t apply to the study type is skipped, never penalized.
This Kaimen Rigor review is model-assisted and is not a substitute for formal expert review. It complements human evaluation by surfacing potential methodological concerns — verify each finding against the source.