We performed a randomized, double-placebo, double-blind clinical trial of 18 months duration in patients with a rheumatic disease, starting GCs in a dosage of 7.5 mg prednisone equivalent daily or higher. Two hundred one patients were allocated to receive either alendronate 10 mg and alfacalcidol-placebo daily or alfacalcidol 1 microgram and alendronate-placebo daily. Primary outcome was change in bone mineral density of the lumbar spine in 18 months, secondary outcome incidence of (symptomatic) morphometric vertebral deformities.