King 1984.

Methods	Within‐participant, randomised controlled study This study was conducted at a single centre in a secondary care setting in the UK
Participants	20 participants with chronic palmar eczema Evaluable: 15 (8 hyperkeratotic, 7 pompholyx). Dropouts: 5 Inclusion criteria of the trial Chronic symmetrical palmar eczema unresponsive to topical steroids or tar Stable for at least 3 months before the beginning of the study Exclusion criteria of the trial Pregnancy Under 25 years of age Treatment with oral steroids or cytotoxic agents History of skin neoplasia or previous radiotherapy Study population Gender: not stated Age: not stated
Interventions	Intervention • Superficial ionising radiation fractionated 100 rad at 45 kV once weekly for 3 weeks; total dose 300 rad in 15/20 hands Control intervention • Placebo radiation once weekly for 3 weeks in 15/20 contralateral hands In both groups, the topical medication was continued unchanged Duration 3 weeks' active treatment with follow‐up until 6 months
Outcomes	Primary outcomes of the trial Not defined Other outcomes Observer‐rated assessment of extent of lesions: good response (clear and nearly clear) vs poor response (partly clear, no change, relapse). Response was assessed at 1, 3, and 6 months Photographs
Notes	Outcome 2 (photographs) was not used in the presentation of results 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)	Unclear risk	Quote: "the radiographer randomly selected one palm..." Comment: no further details are given
Allocation concealment (selection bias)	Low risk	Quote: "neither patient nor doctor was aware which hand had received treatment, but a record was kept by a radiographer in a sealed envelope" Comment: the study used sealed envelopes. This is a clear description of an adequate allocation concealment procedure
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "neither patient nor doctor was aware which hand had received treatment, but a record was kept by a radiographer in a sealed envelope" Comment: double‐blinded. One hand received actual radiotherapy; the other received "simulated radiotherapy" in the same regimen. This was considered as an adequate way to blind participants. The radiographer (staff) was aware of the treatment arm, but we consider this the best possible way to blind participants
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "neither patient nor doctor was aware which hand had received treatment, but a record was kept by a radiographer in a sealed envelope" Comment: double‐blind design. At the end of the study, the records of the radiographer were studied. Observers had no direct access to the randomisation code due to the sealed envelope and were not involved in administration of treatment. This is considered an adequate method to blind outcome assessors
Incomplete outcome data (attrition bias) All outcomes	High risk	No intention‐to‐treat analysis but per protocol (15 of 20 = less than 80%)
Selective reporting (reporting bias)	Low risk	No trial registration found. We did not find discrepancies between Methods and Results sections
Other bias	Low risk	Baseline comparisons: as within‐participant study not applicable Diagnostic certainty: yes The study was completed