METHODS

Design:

randomised controlled trial.

Allocation:

concealed.*

Blinding:

blinded {data analysts}†.*

Follow-up period:

5 years.

Setting:

40 chest clinics in the UK.

Patients:

352 men and women 50–70 years of age (mean age 60 y, 58% men) who were outpatients; randomisation was violated in 349 patients. Patients had asthma and had been taking regular oral or inhaled glucocorticoids, or both, for ⩾1 year. Only postmenopausal women were included. Women with a hysterectomy were excluded.

Interventions:

patients were stratified by level of glucocorticoid exposure and allocated to oral etidronate, 400 mg/day for 2 weeks every 3 months (n = 81); calcium carbonate, given as 500 mg/day of elemental …