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P791 Influence of patients’ preference in randomised controlled trials

K. Wasmann*1, P. Wijsman2, S. van Dieren3, W. Bemelman4, C. Buskens4

1Amsterdam UMC, Department of Surgery and Gastroenterology, Amsterdam, The Netherlands, 2Spaarne Gasthuis, Department of Internal medicine, Hoofddorp, The Netherlands, 3Amsterdam UMC, Clinical Research Unit, Amsterdam, The Netherlands, 4Amsterdam UMC, Department of Surgery, Amsterdam, The Netherlands

Background

Randomised controlled trials (RCT) are the gold standard to provide unbiased data. However, randomly allocating patients to treatments that do not accord with their preferences may influence participation and outcomes. As, in trials comparing treatments of significant different nature (e.g. surgery vs. medication), eligible patients could decline participation due to preference. This could limit the generalizability of results (reduced external validity). Furthermore, trials comparing experimental vs. standard treatment, are likely to include patients preferring experimental treatment, as trial participation is not needed for patients preferring standard treatment. Randomisation to the (non)-preferred strategy could influence adherence to treatment protocol or influence subjective outcomes (reduce internal validity). To preclude the influence of patients’ preference on validity, a patient preference trial (PPT) has been designed. Patients with a preference for a treatment strategies will be treated accordingly, whereas only those patients without a distinct preference will be randomised in the usual way. The aim of this study was to assess the influence of patients’ preference in RCTs.

Methods

In this systematic review and meta-analyses, we searched for PPTs published between January 1, 2005 and October 5, 2018. PPTs reporting on allocation of patients to random- and preference cohorts, while using the same study protocol for both cohorts were included. The main outcomes were external validity (participation and baseline characteristics) and internal validity (lost to follow-up, cross-over and the primary outcome), assessed by comparing standardised effect sizes of the random- and preference cohorts.

Results

In total 117 of 3734 identified articles met screening criteria and 44 were eligible (24873 patients). The participation rate in PPTs was >95% in 14 trials (range 48–100%) and acceptance of randomisation was < 50% in 26 trials (range’s–81%). Higher education, female, older age, race and prior experience with one treatment-arm were characteristics of patients declining randomisation. Lost to follow-up and cross-over rate were significantly higher in the randomised cohort in comparison with the preference cohort. Following a meta-analysis the primary outcomes were comparable, mean difference 0·093(95% CI −0·178;0·364, p = 0·502).

Conclusion

Patients’ preference led to a substantial proportion of a specific patient group refusing randomisation, while it did not influence the primary outcome within a PPT. Therefore, in the era of patients becoming more active participants in research, PPTs could increase participation without compromising the validity of the outcomes compared with RCTs.