Primary and secondary analysis populations
SECONDARY
Given that study and personal data were not linked, we were unable to directly identify the study data from the 268 duplicate entries from the total 603 randomisations which took place during the same period. We therefore produced two datasets for analysis, aiming to protect trial validity by using objective criteria to include only independent, non-suspect responses. The primary analysis population comprised all randomisations and questionnaire responses received outside of the defined contamination period; this included 638 randomisations and 566 completed questionnaires and excluded the 603 randomisations and 597 responses within the contamination period. The secondary analysis population included all randomisations excluding the 208 with questionnaire responses completed in less than 20 seconds; this included 961 randomisations and 833 completions.