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Open Access Publications from the University of California

Factors Associated with Adherence to an End-of-Study Biopsy: Lessons from the Prostate Cancer Prevention Trial (SWOG-Coordinated Intergroup Study S9217)

  • Author(s): Gritz, E. R
  • Arnold, K. B
  • Moinpour, C. M
  • Burton-Chase, A. M
  • Tangen, C. M
  • Probstfield, J. F
  • See, W. A
  • Lieber, M. M
  • Caggiano, V.
  • Moody-Thomas, S.
  • Szczepanek, C.
  • Ryan, A.
  • Carlin, S.
  • Hill, S.
  • Goodman, P. J
  • Padberg, R. M
  • Minasian, L. M
  • Meyskens, F. L
  • Thompson, I. M
  • et al.

Background: The Prostate Cancer Prevention Trial (PCPT) was a 7-year randomized, double-blind, placebocontrolled trial of the efficacy of finasteride for the prevention of prostate cancer with a primary outcome of histologically determined prevalence of prostate cancer at the end of 7 years. Methods: A systematic modeling process using logistic regression identified factors available at year 6 that are associated with end-of-study (EOS) biopsy adherence at year 7, stratified by whether participants were ever prompted for a prostate biopsy by year 6. Final models were evaluated for discrimination. At year 6,13,590 men were available for analysis. Results: Participants were more likely to have the EOS biopsy if they were adherent to study visit schedules and procedures and/or were in good health (P < 0.01). Participants at larger sites and/or sites that received retention and adherence grants were also more likely to have the EOS biopsy (P < 0.05). Conclusions: Our results show good adherence to study requirements 1 year before the EOS biopsy was associated with greater odds that a participant would comply with the invasive EOS requirement. Impact: Monitoring adherence behaviors may identify participants at risk of nonadherence to more demanding study end points. Such information could help frame adherence intervention strategies in future trials. © 2014 American Association for Cancer Research.

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