This Delphi survey produced rich information for further development of the SPIRIT Initiative, which aims to develop a guideline for clinical trial protocol content. Recent studies suggest that PubMed indexes over 6,000 RCTs annually
] and this number has likely increased over time
]. This finding does not account for trials indexed in other databases (between 20% and 70% of trials depending on the discipline
]) and the minimum of 40% of trials not reaching full publication
]. Given that all clinical trials should have a protocol, this Delphi and the SPIRIT Initiative have broad applicability.
Our panellists rated many concepts as highly important for inclusion in RCT protocols, most of which had a strong majority favouring inclusion, indicating consensus within the panel (for example narrow IQRs). The importance of some of these concepts, such as allocation concealment, outcomes (including delineation of primary outcomes), roles of sponsors, and conflicts of interest, are substantiated by strong empirical evidence associating them with risk of bias in trials
]. Other concepts are supported by more pragmatic, regulatory or ethical rationale. Importantly, many of these concepts are often not described in protocols of RCTs
]. This may be, in part, because most existing protocol content guidelines do not recommend such concepts
]. The reasons for the variation between existing guidelines and our results are unclear as most guidelines do not report their methods of development.
Our results also indicate where panellists favoured excluding concepts and where a clear consensus was not attained. For the former, such as Budget and Logistics, the lack of support does not suggest that such items should not be included in protocols; only that they may be context-specific (for example not necessary for journal publication of protocols) and thus are not appropriate in a minimum set of requirements. Examples of the latter include items where wide IQRs remained. We believe that a systematic review of the methodological literature is important to complement the Delphi results and to guide and substantiate final recommendations.
Beyond the utility of the Delphi results for trialists, REC/IRBs representatives, funding agencies and the SPIRIT group, this research may be relevant to those developing reporting guidelines and our experience has already helped shape the methodology of other ongoing initiatives. Selecting potential panellists should be given adequate time and attention to ensure they meet the criteria suggested by previous guidance
] as this is pivotal to both the internal and external validity (generalizability) of the Delphi results. Future endeavours should also consider empirically supported strategies to help increase response rates
] including those used in the current study: survey prenotification/invitation to participate, personalized invitations and surveys, notification of and adherence to expected timelines, clear outline of expectations including time-commitments, written commitment by panellists to participate (reply by email), follow-up reminders to non-respondents, provision of previous rounds’ responses and assurance of confidentiality. We also pilot tested each round, collected panellists’ comments and employed a flexible survey design. Using an Internet-based tool may substantially increase Delphi efficiency and is recommended for future work.
Despite the many benefits of the Delphi consensus technique, the results are only as valid as the opinions of the experts constituting the panel. Even if consensus is attained, validating whether this consensus represents the ‘truth’ is not possible, and we recognize that expert opinion remains among the lowest levels of empirical evidence
]. To safeguard the validity of our results, we carefully selected a panel representing key stakeholders. Structured, predefined methods were employed to minimize biased response collation. Importantly, our panellists were experienced and committed to completing the process, increasing internal validity of the results.
We chose the Delphi consensus method
] for this work for several reasons: the research problem was felt to benefit from expert opinion on a collective basis; a larger and more diverse group could be consulted than could effectively meet face-to-face due to expense, size and the logistics of group interaction; and the preservation of participant anonymity allowed for open discussion. This method also shares the advantages of other integrative methods of knowledge translation
] ideally resulting in a guideline that, beyond being founded on transparent and systematic methods, is externally valid and ultimately meets the needs of end users. We recommend this technique to others embarking on similar initiatives.