| Methods |
Open randomised controlled crossover trial. |
| Participants |
45 patients with severe perennial asthma. Patients were selected from asthmatics treated by the Allergy‐Immunology Service army medical centre. Age range was 15 to 62 years. All patients were taking a mixture of asthma medications including: prednisone, inhaled beclomethasone, methylxanthines and adrenergic bronchodilators. |
| Interventions |
The patients underwent open challenge over several days and in variable/random order with the following drugs and additives: acetylsalicylic acid, tartrazine, azo dye mix, non‐azo dye mix, sodium benzoate and butylated hydroxyanisole/hydroxytoluene. Placebo was clear gelatine capsules and could not be visually differentiated. Tartrazine challenge doses were 2.5, 5, 10, 15 and 20mg. A decrease in FEV1 of >25% was considered a positive challenge. Pulmonary function testing was repeated at 20‐min intervals following ingestion of the test does. If no significant change in FEV1 occurred by 1 hours the next higher dose was given. |
| Outcomes |
FVC, FEV1, PEFR. 25% fall in FEV1 defined a positive test result. |
| Notes |
No data provided on placebo arm. Only positive tests to tartrazine provided. No reply to correspondence received from author to date. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
Information not available |
