Table 1 How an internet-based trial can meet the quality criteria of the revised CONSORT statement

TITLE AND ABSTRACT

How participants were allocated to interventions is comparable to traditional RCTs

INTRODUCTION Background

Scientific background and explanation of rationale is comparable to traditional RCTs

METHODS Participants

Eligibility criteria for participants needs to be confirmed by a third person as the researchers do not see the participants. In 159 out of 160 consent forms a reply was obtained from the participants' primary care physician or rheumatologist. Settings and locations are generally online and remote access in an internet-based trial.

Interventions

Interventions in an internet-based trial can only be those that the participant administers themselves and are stable enough to be sent in the post. The probiotic intervention fulfilled both these requirements.

Objectives

Specifying objectives and hypotheses is comparable to traditional RCTs

Outcomes

Outcome measures for an internet-based RCT generally need to be self assessment measures. However, postage of samples (such as blood samples taken at the local hospital or primary care practice) could be feasible. The use of internet-based questionnaires to assess disease severity in SpA has previously been validated[21]

Sample size

Determination of sample size, stopping rules and interim analysis are comparable to traditional RCTs

Randomization – sequence generation

Randomization is comparable to traditional RCTs

Randomization – allocation concealment

Allocation concealment is easier with an internet-based RCT as the researchers never meet the participants and can only randomise after the details of the participants have been entered into the data collection system. Researchers did not know who was in group A or B until after all data had been collected and the database cleaned. The identity of group A or B was not revealed until after all the analysis was completed. Participants never knew if they were in group A or B.

Randomisation – implementation

The allocation sequence was generated by different individuals to those recruiting and to those giving the medication to participants. No member of the research team met the participants

Blinding (masking)

Blinding is feasible using internet-based trials as participants are unlikely to meet in order to compare treatments, researchers never meet participants so have limited ability see effects of treatments and the analyst can be kept completely blinded as the database does not contain any reference to allocation groups until all data collection and data cleaning has been completed.

Statistical methods

Statistical methods are comparable to traditional RCTs

RESULTS Participant flow

Participant flows are comparable to traditional RCTs. However, participants can drop out without giving reasons. Therefore perhaps additional measures to follow people such as telephone contact, is needed.

Recruitment

Dates defining the periods of recruitment and follow-up is comparable to traditional RCTs

Baseline data

The characteristics collected are all self reported but can be validated by a third person such as the participants medical practitioner

Numbers analyzed

Internet-based trial must use intention to treat as there is no way of assessing compliance. Internet-based trials can measure pragmatic effectiveness and not efficacy

Outcomes and estimation

Analysis presentation is comparable to traditional RCTs

Ancillary analysis

Analysis for an internet-based RCT is comparable to that in traditional RCTs

Adverse events

Adverse events are harder to report in an internet-based RCT than in a traditional RCT. There is reliance on the participants to report adverse events. This is the reason why internet-based trials can only be conducted on safe interventions.

DISCUSSION Interpretation

Interpretation of an internet-based RCT is comparable to that of a traditional RCT

Generalizability

Generalizability may be affected as participants are a very selected sample. Participants need to have access to the internet/e-mail, the knowledge to use the internet/e-mail and the motivation to self refer to join a trial. However, generalizability of traditional RCTs is compromised by the artificial environment of frequent clinical visits, this bias does not apply to the internet-based RCT.

Overall evidence

Overall evidence in an internet-based RCT is comparable to that in a traditional trial