Burney 1989.
Methods | Randomised placebo‐controlled cross‐over study. . | |
Participants | 36 participants (14 men, 22 women) with moderately severe asthma were included in the study. Age range 18 to 53 years. 9 current smokers, 10 ex‐smokers and 17 never smoked. 35 subjects on inhaled bronchodilators and 12 using inhaled steroids. | |
Interventions | After one week run‐in, subjects were put on a low sodium diet and asked to take either slow sodium tablets (80 mmol/day) or placebo. After a 2‐week period the subjects were crossed over (no wash‐out period). Study measurements were performed after the run‐in period, 2 weeks after first intervention and 2 weeks after the secondary intervention. Exclusion criteria: none stated in the paper. |
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Outcomes | FEV1, FVC, PD20, PD10, skin prick tests and blood pressure. | |
Notes | ||
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Unclear risk | No information given in paper. |
Allocation concealment (selection bias) | Unclear risk | Described as randomised; no other information available. |
Blinding (performance bias and detection bias) All outcomes | Unclear risk | Described as blinded; no other information available. |
Incomplete outcome data (attrition bias) All outcomes | High risk | 5 subjects were excluded but not included in the analysis. |
Selective reporting (reporting bias) | Unclear risk | Not clear from the information presented. |
Other bias | Unclear risk | The significant results are only present in men and has no calculation of power described. There was no wash‐out period. |