Alendronate effect on the prevention of bone loss in early stages of ankylosing spondylitis : a randomized, double-blind, placebo-controlled pilot study

Ankylosing spondylitis (AS) is an inflammatory rheumatic disease that leads to a progressive ankylosis of vertebras and ossification of paravertebral ligaments. Bone loss and osteoporosis are amongst the important complications of AS, treatment of which is a challenging issue. Objectives: This study aimed to clarify the effect of alendronate on the prevention of bone loss in patients with early AS. Patients and Methods: In a randomized, double-blind, placebo-controlled study, 24 patients with early stages of AS were recruited in Emam Reza Hospital, Tabriz University of Medical Sciences. The diagnostic criteria of early AS were Schober’s index ≥ 5, normal hip joint in pelvic radiography, and absence or rarity of syndesmophytes in spine radiography (Taylor index ≤ 1). The participants were randomly allocated to the treatment and control groups and received 70 mg/week of alendronate and the same dose of placebo, respectively, for 12 months. Before and 12 months after the intervention, bone densitometry was performed from lumbar and pelvic region using the dual-energy X-ray absorptiometry (DEXA) method with Hologic QDR model instrument. Patients, physicians who prescribed the medications and those who interpreted the outcomes, and densitometry technicians were unaware of the assigned medication to each patient. Both groups received supplemental calcium (1000 mg/day) and vitamin D (400 mg/day). Results: After 12 months of treatment, hip and lumbar bone mineral density differences were not statistically significant between study groups (P = 0.061 and P = 0.112, respectively). No case of clinically apparent vertebral and nonvertebral fracture were observed in the treatment and control groups. Conclusions: Our results suggested that applying alendronate was ineffective in preventing bone loss in patients with early stages of AS.