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Which orthopaedic trauma patients are likely to refuse to participate in a clinical trial? A latent class analysis
  1. Nathan N O’Hara1,
  2. Yasmin Degani1,
  3. Debra Marvel2,
  4. David Wells2,
  5. C Daniel Mullins3,
  6. Stephen Wegener4,
  7. Katherine Frey5,
  8. Tara Joseph5,
  9. Jonathan Hurst1,
  10. Renan Castillo5,
  11. Robert V O’Toole1
  12. on behalf of PREVENT CLOT Stakeholder Committee
    1. 1 Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland, USA
    2. 2 PREVENT CLOT Stakeholder Committee, Baltimore, Maryland, USA
    3. 3 Department of Pharmaceutical Health Services Research, University of Maryland School of Pharmacy, Baltimore, Maryland, USA
    4. 4 Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
    5. 5 Department of Health Policy and Management, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
    1. Correspondence to Mr Nathan N O’Hara; nohara{at}


    Objective The study aimed to assess systematic differences in the characteristics of patients that consented for the trial compared with the broader pool of eligible patients in a large, pragmatic orthopaedic trauma trial.

    Design A retrospective observational study performed from April 2017 to March 2018.

    Setting Academic trauma centre in Baltimore, USA.

    Participants There were 642 eligible adult trial participants with an operative fracture to the appendicular skeleton and were indicated for blood clot prophylaxis. The median age of the sample was 50 years (IQR: 31–63), and 60% were male.

    Primary outcome measure The primary outcome was the refusal to enrol in the trial. Demographic and injury covariates were included in iterations of latent class models. The final model was selected based on a minimum Bayesian information criterion.

    Results The final model identified three clusters with five covariates predictive of cluster membership (age, neighbourhood-based socioeconomic status, alcohol use, multiple fractures, multiple surgeries). The three clusters were associated with 22% (Cluster 1), 38% (Cluster 2) and 62% (Cluster 3) refusal rates, respectively. Members of Cluster 3 (n=84) were most commonly between 66 and 80 years of age (49% vs 6% (Cluster 1) and 21% (Cluster 2)), of high neighbourhood-based socioeconomic status (85% vs 63% (Cluster 1) and 8% (Cluster 2)), with isolated fractures (100% vs 80% (Cluster 1) and 92% (Cluster 2)), and were less likely to have multiple surgeries compared with the other clusters (28% vs 47% (Cluster 1) and 35% (Cluster 2)).

    Conclusion In this study, the likelihood of refusing to participate in the trial ranged from 22% to 62% in the three identified clusters. Elderly age, high socioeconomic status, and less severe injuries defined the cluster that was most likely to refuse trial participation.

    Trial registration number NCT02984384.

    • clinical trials
    • trauma management
    • thromboembolism

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    • Collaborators PREVENT CLOT Stakeholder Committee Members (Study Group Name): Stephen Breazeale; Randolph Fenninger; Steven Herndon; Eileen Flores; Stephen Fisher; Michelle Medeiros; Brianna Fowler.

    • Contributors NNO contributed to the literature search, study design, data analysis, data interpretation, writing and critical revision. YD and JH contributed to the data collection, data interpretation and critical revision. DM, DW, CDM, SW, TJ and RC contributed to the data interpretation and critical revision. KF contributed to the literature search, data interpretation and critical revision. RVO contributed to the study design, data interpretation and critical revision. All authors have approved the final version of the article submitted and agree to be accountable for all aspects of the work.

    • Funding Research reported in this manuscript was funded through a Patient-Centered Outcomes Research Institute (PCORI) Award (PCS-1511-32745). The views in this publication are solely the responsibility of the authors and do not necessarily represent the views of the PCORI, its board of governors, or methodology committee.

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Ethics approval The study was reviewed and approved by the University of Maryland School of Medicine Institutional Review Board (HP-00073404).

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement Data are available upon reasonable request.

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