CONSORT 2010 statement: extension checklist for reporting within person randomised trials

s for within person RCTs should indicate the paired or within person nature of the trial. Table 1⇓ shows the minimum information that should be included in the abstract of a within person trial, in addition to the items recommended for all trials. We were not able to find examples of good reporting that tackled all the items required. We therefore developed an example abstract by enhancing a published abstract (fig 2⇓). Methods Item 3a: Trial design Standard CONSORT item—Description of trial design (such as parallel, factorial) including allocation ratio. Extension for within person trials—Rationale for using a within person design and identification of body sites. Example 1—“In this study, we present the results of a contralateral eye study in which patients were randomised to undergo implantation with either the Tecnis ZM900 silicone multifocal intraocular lenses (MIOL) or the Tecnis ZMA00 acrylic multifocal IOL [intraocular lens]. Using a contralateral study model, we are able to reduce many of the variables that can occur between patient groups.” Example 2—“The GDPs recruited children who had caries affecting pairs of primary molar teeth, which were matched for tooth type, arch and extent of caries.” Explanation—The within person design avoids possible imbalance between interventions on participant level variables. The within person design is efficient, because a smaller sample size is required than for a standard design, and losses to follow-up are usually equal between treatment groups. However, carry across effects might reduce efficiency and bias the trial results—such a design should not be implemented if a carry across effect is expected. All alternatives must be considered, and if a within person trial design is used it must be made clear why it was judged to be the most appropriate and robust design. The treatment of the body sites can be concurrent or a sequential (see item 5). In within person designs baseline characteristics are balanced at the participant level, but imbalances can occur for site specific variables, notably severity of disease. The identification and selection process of the included sites should be described, as shown in example 2, if applicable. Item 4a: Eligibility criteria for participants Standard CONSORT item—Eligibility criteria for participants. Extension for within person trials—Eligibility criteria for body sites. Example—“The inclusion criterion was uncomplicated age related bilateral cataract with the potential to see 20/40 or better in each eye. Exclusion criteria were any concurrent medication apart from ocular lubricants, any coexisting ocular pathology, unilateral amblyopia, previous intraocular surgery or laser treatment, retinal complications, pupil dilatation <7 mm, any surgical complications or inability to co-operate or maintain follow-up.” Explanation—In within person trials two sets of eligibility criteria are needed: the eligibility of the individual participant and the eligibility of the body site (such as limb or eye). For participants to be eligible in a within person design, they must be able to provide at least two body sites to be treated, one to receive each intervention. Eligibility criteria for the body sites should include criteria related to the comparability between sites within a person. Item 5: Interventions for each group Standard CONSORT item—The interventions for each group with sufficient details to allow replication, including how and when they were actually administered. Extension for within person trials—Whether interventions were given sequentially or concurrently. Example 1:Concurrent application of interventions—“Patients were given simultaneous injections of buffered and unbuffered 2% lidocaine with epinephrine 1:100 000. The needles were inserted simultaneously and the anesthesia was injected for a 20 second count for a total volume of 1.0 ml per injected side.” Example 2: Sequential application of interventions—“An investigator with no clinical involvement in the trial used the list to prepare directions assigning one of the intraocular lenses (IOLs) (iMics1 NY-60 IOL or AcrySof SN60WF IOL) for placement into the patient’s right eye, the first eye to be operated. The directions for each operation were placed in sequentially numbered and sealed envelopes. The surgeon opened the envelopes in sequence on the day of surgery after hydrodissection and phacoemulsification and implanted the randomly assigned IOL specified into the patient’s first eye. The second eye was implanted with the other IOL one week later.” 38 Explanation—In addition to the standard CONSORT explanation of detailed reporting of interventions for the purposes of reproducibility, it is important to describe whether the intervention was applied to different body sites concurrently or sequentially. There are several reasons for this. Firstly, the intervention on one site may dilute the effect on contralateral site due to potential carry across effect (although ideally trials with likely carry across effects would not have used a within person design). Secondly, in sequential designs the time between interventions might be long, so the baseline state of the untreated No commercial reuse: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribe BMJ 2017;357:j2835 doi: 10.1136/bmj.j2835 (Published 2017 June 30) Page 4 of 22 RESEARCH METHODS & REPORTING