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A prospective cohort and extended comprehensive-cohort design provided insights about the generalizability of a pragmatic trial: the ProtecT prostate cancer trial

Lookup NU author(s): Dr Edgar Paez-Gueyraud



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


© 2018 The Authors Objectives: Randomized controlled trials (RCTs) deliver robust internally valid evidence but generalizability is often neglected. Design features built into the Prostate testing for cancer and Treatment (ProtecT) RCT of treatments for localized prostate cancer (PCa) provided insights into its generalizability. Study Design and Setting: Population-based cluster randomization created a prospective study of prostate-specific antigen (PSA) testing and a comprehensive-cohort study including groups choosing treatment or excluded from the RCT, as well as those randomized. Baseline information assessed selection and response during RCT conduct. Results: The prospective study (82,430 PSA-tested men) represented healthy men likely to respond to a screening invitation. The extended comprehensive cohort comprised 1,643 randomized, 997 choosing treatment, and 557 excluded with advanced cancer/comorbidities. Men choosing treatment were very similar to randomized men except for having more professional/managerial occupations. Excluded men were similar to the randomized socio-demographically but different clinically, representing less healthy men with more advanced PCa. Conclusion: The design features of the ProtecT RCT provided data to assess the representativeness of the prospective cohort and generalizability of the findings of the RCT. Greater attention to collecting data at the design stage of pragmatic trials would better support later judgments by clinicians/policy-makers about the generalizability of RCT findings in clinical practice.

Publication metadata

Author(s): Donovan JL, Young GJ, Walsh EI, Metcalfe C, Lane JA, Martin RM, Tazewell MK, Davis M, Peters TJ, Turner EL, Mills N, Khazragui H, Khera TK, Neal DE, Hamdy FC, Bollina P, Catto J, Doble A, Doherty A, Gillatt D, Gnanapragasam V, Holding P, Hughes O, Kockelbergh R, Kynaston H, Mason M, Oxley J, Paul A, Paez E, Rosario DJ, Rowe E, Staffurth J

Publication type: Article

Publication status: Published

Journal: Journal of Clinical Epidemiology

Year: 2018

Volume: 96

Pages: 35-46

Online publication date: 27/12/2017

Acceptance date: 11/12/2017

Date deposited: 19/03/2018

ISSN (print): 0895-4356

ISSN (electronic): 1878-5921

Publisher: Elsevier USA


DOI: 10.1016/j.jclinepi.2017.12.019


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