Eleven extensions and five elaborations to the SPIRIT 2013 checklist are recommended for inclusion in clinical trial protocols where PROs are a primary or key secondary outcome. Extension items focused on PRO specific issues relating to the: trial rationale, objectives, eligibility criteria, concepts used to evaluate the intervention, time points for assessment, PRO instrument selection and measurement properties, data collection plan, translation to other languages, proxy completion, strategies to minimise missing data and whether PRO data will be monitored during the study to inform clinical care.