Cartwright 1987.

Methods	Within‐participant, randomised controlled trial This was a single‐centre study, conducted in the UK
Participants	30 participants with bilateral symmetrical constitutional hand eczema, resistant to previous treatment Dropouts: 12 Inclusion criteria of the trial Resistant bilateral hand eczema Exclusion criteria of the trial Not defined Study population Gender: not stated Age: not stated
Interventions	Intervention • Superficial X‐ray 300 Rad 10 kV 3 times with a 21‐day interval in 18/30 hands Control intervention • Placebo‐radiation in 18/30 contralateral hands 3 times with a 21‐day interval Participants were followed up for 18 weeks after initial treatment Participants continued application of tar paste or steroid ointments throughout the trial Duration 21 weeks (3 weeks active treatment, 18 weeks follow‐up)
Outcomes	Primary outcomes of the trial Not defined. Other outcomes Participant‐rated severity score on scale 0 to 10 with increasing severity Observer‐rated score 0 to 4 (0 = no eczema; 1 = eczema, mild scaling; 2 = erythema, scaling, fissures; 3 = erythema, severe scaling, bleeding fissures; 4 = active pompholyx) Adverse events
Notes	Secondary outcomes ‐ reduction in severity, investigator‐ and participant‐rated scoring ‐ were included but provided no reproducible data. Only graphic representation of outcome scores. Graphs in Figures 1 and 2 seem to have been exchanged. High dropout: 12 out of 30. Reasons given for the 12 dropouts: unwilling to attend, mostly because eczema improved Declarations of interest: not stated Funding: not stated Sample size rationale: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "according to a predetermined random code known by the radiographer..." Reference to a predetermined random code known only by the radiographer
Allocation concealment (selection bias)	Unclear risk	No details about how allocation was concealed from participants and investigators, although the article states that only the radiographer knew the randomisation code
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "according to a predetermined random code known by the radiographer and unknown to patient and observer, one hand was irradiated with 300 rad (3 Gy) of Grenz rays (...) and the other hand treated in an exactly similar manner, except that sham therapy was given" Comment: participants were truly blinded and received placebo‐radiation. The radiographer was the only one aware of the randomisation code in that he had to programme the radiation; however in our opinion, this study could not have been done in another fashion; therefore we judged this trial to have low risk, although not all staff were blinded
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "according to a predetermined random code known by the radiographer and unknown to patient and observer..." Comment: the observer was unaware of the allocation; however no further details are provided
Incomplete outcome data (attrition bias) All outcomes	High risk	No intention‐to‐treat analysis but per protocol (18 of 30 = less than 80%)
Selective reporting (reporting bias)	Unclear risk	No trial registration found. Outcomes mentioned in the Methods section are depicted in graphs and tables in the Results section; however participant‐ and observer‐rated graphs probably are switched because results in the participant section range from 0 to 3, and results for the observer range from 0 to 7
Other bias	Low risk	Baseline comparisons: within‐participant study was not applicable Diagnostic certainty: yes The study was completed