Medici 1993.
Methods | Randomised placebo‐controlled cross‐over study. . | |
Participants | 18 patients recruited (4 excluded during run‐in due to poor compliance). Study group 14(9 men, 5 women). Age range 20 to 65 years. They had stable atopic asthma and fulfilled the ATS criteria for the diagnosis of asthma. Exclusion criteria: instability of asthma, therapy with oral steroids, cromoglycan or diuretics, cardiac insufficiency, arrhythmias, liver diseases, kidney diseases, diabetes mellitus, smoking and pregnancy. |
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Interventions | After 2 weeks on a low sodium diet (86 to 103 mmol/day), given 157 mmol of sodium daily (in the form of sodium chloride) or placebo for 3 weeks. Then the 2 groups were crossed over for a second 3‐week treatment period (sodium citrate with 154 sodium mmol). There was no washout period. | |
Outcomes | PD20, FEV1, FVC, PEFR x 3 a day, inhaler bronchodilator and corticosteroids sprays, number of asthma attacks | |
Notes | ||
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Unclear risk | No information given. |
Allocation concealment (selection bias) | Unclear risk | Described as randomised; no information given. |
Blinding (performance bias and detection bias) All outcomes | Unclear risk | Described as blind, however the papers states that due to side effects when on the salt tablets, less than intended amount was used. |
Incomplete outcome data (attrition bias) All outcomes | Low risk | |
Selective reporting (reporting bias) | Unclear risk | Not clear from information given. |
Other bias | Unclear risk | Subjects had heartburn on the sodium tablets and so could have been unblinded. Subjects changed medication from regular to prn and there was no wash‐out period. No calculation of power described. |