Lindelöf 1987.

Methods	Within‐participant, randomised controlled study This study was carried out in a secondary care setting at a single centre. The study was conducted in Sweden
Participants	24 participants with chronic hand eczema (13 allergic, 5 atopic, 3 irritant, 2 tylotic, 1 pompholyx) Dropouts: 1 Inclusion criteria of the trial Chronic symmetrical hand eczema unresponsive to topical steroids Stable for at least 3 months Exclusion criteria of the trial Not defined Study population Gender: not stated Age: not stated
Interventions	Intervention • Ionising radiation (Grenz rays, 300 rad) 1× weekly for 6 weeks in 23/24 hands Control intervention • Placebo radiation once a week for 6 weeks in 23/24 contralateral hands Participants were followed up to 10 weeks after initial treatment Duration 10 weeks (6 weeks active treatment, 4 weeks follow‐up)
Outcomes	Primary outcomes of the trial Not defined Other outcomes Observer‐rated severity score (0 = no symptoms, 4 = very severe symptoms for erythema, scaling, itching, vesicles, fissures, and distribution (size of area involved)) at week 5 and week 10 Comparison of number of participants who are better on the treated hand versus number of participants who are better on the placebo hand Adverse events
Notes	The secondary outcome ‐ reduction in severity, investigator‐rated ‐ was included but provided no reproducible data. Total scores are only graphically presented, without statistical analysis 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: "the treatments were administered by a nurse according to a predetermined randomized code unknown to both patients and doctors" Comment: reference to a predetermined randomisation code
Allocation concealment (selection bias)	Low risk	Quote: "the treatments were administered by a nurse according to a predetermined randomized code unknown to both patients and doctors" Comment: by including a third person, neither the physician/observer, nor the participants can be aware of the treatment allocation. Therefore we considered this as low risk of bias
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "the treatments were administered by a nurse according to a predetermined randomised code unknown to both patients and doctors" Comment: double‐blinded. Placebo therapy was achieved by "allowing the apparatus to hum without emitting radiation", which could be considered as adequate; however the treatments were administered by a nurse who was aware of the predetermined randomised code. Although one might argue that part of the staff was aware of the treatment allocation, we decided this is the best way to blind participants
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "the treatments were administered by a nurse according to a predetermined randomized code unknown to both patients and doctors" Comment: the observer was blinded, and treatment was administered by someone else
Incomplete outcome data (attrition bias) All outcomes	Low risk	No intention‐to‐treat analysis but per protocol (23 of 24 = more than 80%)
Selective reporting (reporting bias)	Low risk	No trial registration found. No major differences between the Methods and Results sections
Other bias	Low risk	Baseline comparisons: as within‐participant study not applicable Diagnostic certainty: yes The study was completed