Dawe 2005.

Study characteristics
Methods	Two‐group parallel split‐body, phase III randomised controlled trial with paired comparison of right versus left limb Setting: single‐centre study located in Scotland, UK Duration of enrolment: February 2002 to February 2003 Follow‐up time: until relapse or up to 12 months
Participants	Inclusion criteria of the trial Chronic plaque psoriasis; chronic was defined as a history of psoriasis present, or recurring, for at least 1 year Exclusion criteria of the trial Not reported Characteristics Skin type (N, %): I: 9 (15%), II: 30 (50%), III: 21 (35%) Severity: not reported Previous treatment: any experience of former phototherapy: UVB: 62% (36 of 60), psoralen bath + UVA: 13% (8 of 60); previous systematic antipsoriatic agents: 12% (7 of 60). Duration of condition: not reported
Interventions	Intervention (n = 60 lower extremity) Dead Sea salt bath followed by narrow‐band UVB was allocated randomly to the right or left limb of each patient. The allocated limb was soaked in a solution of Dead Sea salt for 15 min (see treatment regimens) and whole‐body phototherapy then given according to our standard departmental protocol. On completion of the treatment course, patients were followed up every 8 weeks until relapse or for up to 1 year. Dead Sea salt soaks : Mavena Healthcare Mg 46 DS salt ('Sea of Life') was used. The composition of this was MgCl2 46% minimum, CaCl2 2.2% maximum, NaCl 0.8% maximum, KCl 0.5% maximum, and water of crystallisation. A 15% by weight solution of this (3.6 kg in 24 L tap water) was used for soaking arms or legs. The salt solution was at 37 °C at the start of the 15‐minutes soak. The soaked limb was gently towel dried and UV administration was commenced within 10 min of the soak. The soaked limb was rinsed under tap water after UV exposure. Concentration: 150 g/L Dead Sea salt dissolved in tap water. Artificial narrowband UVB : a standard regimen, with starting dose based on minimal erythemal dose (MED) determination, then three times weekly treatment with dose increments of 20% (reducing to 10%, adjusted according to individual erythemal responses to each treatment) was used. The first 20 patients (with sufficiently clear forearm skin) recruited had a MED assessment carried out on a soaked forearm and an unsoaked forearm. For MED determination in patients with skin phototypes I and II, doses administered were 25, 50, 70, 100, 140, 200, 280 and 390 mJ cm‐2. For patients with skin phototype III, the first two doses were omitted and doses of 550 and 770 mJ cm‐2 added. The MED was defined as the lowest dose to produce just perceptible erythema at 24 hours. There were no consistent differences between the paired MED assessments, so patients recruited thereafter received a MED assessment on back skin only. The phototherapy cubicles used were either Waldman UV5000, fitted with 24 Philips 100 W TL‐01 lamps, or a Ninewells Medical Physics Department cubicle, fitted with 50 Philips 100 W TL‐01 lamps. Irradiance was measured monthly using an IL1400A meter (International Light Inc., Newburyport, MA, U.S.A.) calibrated for TL‐01 irradiation in the Photobiology Unit's optical radiation laboratory (traceable to the U.K. National Standards maintained by the National Physical Laboratory). The mean cumulative UVB dose was 24.4 J/cm2. Control intervention (n = 60 lower extremity other side) Artificial narrowband UVB alone : the same conditions as reported for the intervention. The mean cumulative UVB dose was 24.4 J/cm2. Both both legs received the same number of treatments with a mean of 25 applications. Duration of UV irradiation was not reported.
Outcomes	Primary outcomes of the trial Change in psoriasis severity (Scaling, Erythema and Induration (SEI) score). The sum of Scaling, Erythema and Induration (SEI) scores, each on a 0–4 scale, was used as a psoriasis severity measure for each of the selected site symmetrical plaques. Duration of psoriasis remission Secondary outcomes of the trial Comparison of minimal erythemal dose Erythemal intensity with and without Dead Sea salt soaking prior to narrow‐band UVB in the first 20 study participants in whom MED testing was performed on both Dead Sea salt soaked and not soaked forearms Scaling, erythema, and induration score measured at 8 months after end of treatment.
Notes	Quote (page 615): "The sum of Scaling, Erythema and Induration (SEI) scores, each on a 0–4 scale, was used as a psoriasis severity measure for each of the selected site symmetrical plaques. This is a modification of the Psoriasis Area and Severity Index we used in other studies." Comment: not defined as outcome. Quote (page 615): "Adverse effects were documented as in standard practice. Erythema was recorded as grade 1 (mild and asymptomatic), grade 2 (well‐demarcated, not painful), grade 3 (painful) and grade 4 (severe with blistering)." Comment: not defined as outcome. Quote (page 615): "Blinding was achieved by: (i) randomization as above." Comment: blinding cannot be achieved by randomisation. Conflicts of interest: Quote "We are grateful to Mavena Healthcare AG, Switzerland who funded this study and provided the Dead Sea salt used. Mavena was not involved in the design, conduct or analysis of the study."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote (page 615): "The study treatment administered to each side was allocated randomly, both as a measure to ensure successful assessor blinding and also to avoid allocation bias. A blocked random allocation list (variably sized blocks) was generated with user‐written software ('ralloc' command) for Stata (Stata 7.0; Stata Corporation, College Station, TX, U.S.A., 2001)." Comment: the authors clearly described an adequate random sequence generation, which was judged as low risk of bias.
Allocation concealment (selection bias)	Low risk	Quote (page 615): "Allocated treatments for each successive entrant to the study were placed in sealed, opaque envelopes which were opened by a nonblinded research nurse only after each patient had signed the informed consent form." Comment: the authors clearly described an adequate concealment of the allocation, which was judged as low risk of bias.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote (page 615): "Blinding was achieved by: (i) randomization as above; (ii) ensuring assessments were always performed before soaks; and (iii) reminders by the nonblinded study nurse to patients not to tell the assessing doctor which limb was receiving the soaks. Patients were not blinded." Comment: patients and nurse were not blinded, while physicians appeared to be blinded. Thus, we judged an unclear risk of bias.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote (page 615): "Those assessing psoriasis severity (SEI) scores were kept unaware of which side was receiving Dead Sea salt soaks. Blinding was achieved by reminders by the nonblinded study nurse to patients not to tell the assessing doctor which limb was receiving the soaks." Comment: we judged an unclear risk as blinding was tried but was not achieved. Blinding effects were not evaluated.
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote (page 615): "Forty‐one (68%) participants remained in the study throughout their UVB course. The 19 study withdrawals were because of: [...]" Comment: 32% of patients withdrew. We think that the proportion of dropouts is high and may affect the outcome. Thus, we judged a high risk of attrition bias
Selective reporting (reporting bias)	Unclear risk	Quote (page 616): "For the 41 patients who reached clearance or minimal residual activity while participating in the study there was no detectable difference [...]" Comment: we are not positive if this may considerably affect the outcome and we judged an unclear risk of bias.
Other bias	Unclear risk	Comment: we did not identify other bias such as design‐specific risks of bias, baseline imbalance, blocked randomisation in unblinded trials, and differential diagnostic activity.