PlumX Metrics
Embed PlumX Metrics

Concordance of results from randomized and observational analyses within the same study: A re-analysis of the women's health initiative limited-access dataset

PLoS ONE, ISSN: 1932-6203, Vol: 10, Issue: 10, Page: e0139975
2015
  • 11
    Citations
  • 0
    Usage
  • 116
    Captures
  • 0
    Mentions
  • 4
    Social Media
Metric Options:   Counts1 Year3 Year

Metrics Details

  • Citations
    11
    • Citation Indexes
      9
    • Clinical Citations
      1
      • PubMed Guidelines
        1
    • Policy Citations
      1
      • Policy Citation
        1
  • Captures
    116
  • Social Media
    4
    • Shares, Likes & Comments
      4
      • Facebook
        4

Article Description

Background Observational studies (OS) and randomized controlled trials (RCTs) often report discordant results. In the Women's Health Initiative Calcium and Vitamin D (WHI CaD) RCT, women were randomly assigned to CaD or placebo, but were permitted to use personal calcium and vitamin D supplements, creating a unique opportunity to compare results from randomized and observational analyses within the same study. Methods WHI CaD was a 7-year RCT of 1g calcium/400IU vitamin D daily in 36,282 post-meno-pausal women. We assessed the effects of CaD on cardiovascular events, death, cancer and fracture in a randomized design-comparing CaD with placebo in 43% of women not using personal calcium or vitamin D supplements- and in a observational design-comparing women in the placebo group (44%) using personal calcium and vitamin D supplements with non-users. Incidence was assessed using Cox proportional hazards models, and results from the two study designs deemed concordant if the absolute difference in hazard ratios was <0.15. We also compared results from WHI CaD to those from the WHI Observational Study(WHI OS), which used similar methodology for analyses and recruited from the same population. Results In WHI CaD, for myocardial infarction and stroke, results of unadjusted and 6/8 covariate-controlled observational analyses (age-adjusted, multivariate-adjusted, propensity-adjusted, propensity-matched) were not concordant with the randomized design results. For death, hip and total fracture, colorectal and total cancer, unadjusted and covariate-con-trolled observational results were concordant with randomized results. For breast cancer, unadjusted and age-adjusted observational results were concordant with randomized results, but only 1/3 other covariate-controlled observational results were concordant with randomized results. Multivariate-adjusted results from WHI OS were concordant with randomized WHI CaD results for only 4/8 endpoints. Conclusions Results of randomized analyses in WHI CaD were concordant with observational analyses for 5/8 endpoints in WHI CaD and 4/8 endpoints in WHI OS.

Bibliographic Details

http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84947786074&origin=inward; http://dx.doi.org/10.1371/journal.pone.0139975; http://www.ncbi.nlm.nih.gov/pubmed/26440516; https://dx.plos.org/10.1371/journal.pone.0139975.t005; http://dx.doi.org/10.1371/journal.pone.0139975.t005; https://dx.plos.org/10.1371/journal.pone.0139975.t004; http://dx.doi.org/10.1371/journal.pone.0139975.t004; https://dx.plos.org/10.1371/journal.pone.0139975; https://dx.plos.org/10.1371/journal.pone.0139975.t001; http://dx.doi.org/10.1371/journal.pone.0139975.t001; https://dx.plos.org/10.1371/journal.pone.0139975.t003; http://dx.doi.org/10.1371/journal.pone.0139975.t003; https://dx.plos.org/10.1371/journal.pone.0139975.t002; http://dx.doi.org/10.1371/journal.pone.0139975.t002; https://dx.plos.org/10.1371/journal.pone.0139975.g001; http://dx.doi.org/10.1371/journal.pone.0139975.g001; https://dx.doi.org/10.1371/journal.pone.0139975.t003; https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0139975.t003; https://dx.doi.org/10.1371/journal.pone.0139975; https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139975; https://dx.doi.org/10.1371/journal.pone.0139975.t002; https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0139975.t002; https://dx.doi.org/10.1371/journal.pone.0139975.t004; https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0139975.t004; https://dx.doi.org/10.1371/journal.pone.0139975.g001; https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0139975.g001; https://dx.doi.org/10.1371/journal.pone.0139975.t001; https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0139975.t001; https://dx.doi.org/10.1371/journal.pone.0139975.t005; https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0139975.t005; http://dx.plos.org/10.1371/journal.pone.0139975.t005; http://dx.plos.org/10.1371/journal.pone.0139975.t001; http://dx.plos.org/10.1371/journal.pone.0139975.g001; https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0139975&type=printable; http://dx.plos.org/10.1371/journal.pone.0139975; http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139975; http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0139975; http://dx.plos.org/10.1371/journal.pone.0139975.t003; http://dx.plos.org/10.1371/journal.pone.0139975.t004; http://dx.plos.org/10.1371/journal.pone.0139975.t002; http://www.plosone.org/article/metrics/info:doi/10.1371/journal.pone.0139975; http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0139975&type=printable

Mark J. Bolland; Andrew Grey; Greg D. Gamble; Ian R. Reid; William B. Coleman

Public Library of Science (PLoS)

Multidisciplinary

Provide Feedback

Have ideas for a new metric? Would you like to see something else here?Let us know