Outcomes after switching from one bisphosphonate to another in 146 patients at a single university hospital.

UNLABELLED: Most patients who switched to a second bisphosphonate continued their treatment long term, although those who stopped their first drug because of adverse events were likely to discontinue the second drug for the same reason. Switching to another bisphosphonate is a reasonable treatment option for some patients with treatment failure.
INTRODUCTION: Patients who experience treatment failure with a bisphosphonate because of adverse events (AEs) or other reasons might receive a second bisphosphonate. However, the frequency and benefits of switching bisphosphonates are unknown.
METHODS: We retrospectively evaluated 197 men and 1110 women newly treated with bisphosphonates between 1 January 2000 and 30 June 2005 at our university hospital.
RESULTS: Among the 497 patients who discontinued bisphosphonate treatment, 146 were switched to a second bisphosphonate. The cumulative probabilities of persistence of treatment after 3 years were 45% with the first bisphosphonate and 65% with the second (P = 0.017). Age >or=65 years, switching bisphosphonates because of AEs, and male gender were associated (P < 0.05) with low persistence of treatment with the second bisphosphonate. Discontinuation of the first drug because of AEs was associated with an increased rate of discontinuation of the second drug because of AEs (hazard ratio, 4.2; 95% confidence interval, 2.1-8.4).
CONCLUSIONS: Patients who switched bisphosphonates had high rates of persistence of therapy. Those who stopped their first bisphosphonate because of AEs were at risk of discontinuing the second drug for the same reason. Switching to another bisphosphonate is a reasonable treatment option for some patients with treatment failure.