Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement
The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.
Switching the Dose Regimen of Oral Bisphosphonates, Adherence and Fractures
Briesacher1, Becky, Andrade2, Susan, Harrold1, Leslie R., Fouayzi2, Hassan, Yood3, Robert A.
To assess adherence and fracture risk in patients who switch dose regimens of oral bisphosphonates.
This is a population-based interrupted times-series analysis using a nationwide administrative health data from 20032006. We identified 1835 switchers of once-weekly to once-monthly oral bisphosphonates and matched them to two comparators using propensity-score methodology: switchers of different once-weekly oral bisphosphonates, and nonswitchers assigned a random switch. We measured adequate adherence as a monthly medication possession ratio >/=0.80 and calculated monthly incidence rate ratios [IRR] of osteoporotic fractures. We tested for pre- and post-switch differences in adherence and fractures rates.
All study groups experienced considerable attrition in adherence: 1 year post-switch, the proportion of adequate adherers was 41% regimen switchers, 47% drug only switchers, and 37% nonswitchers. The regimen switch was associated with decelerated nonadherence (absolute change in monthly attrition rate, -4% pre-switch vs. -1% post-switch, p<.000). There were no significant changes in nonadherence for nonswitchers (absolute change in monthly attrition rate, -4% pre-switch vs. -2% post-switch, p=.578) or drug only switchers (-1% pre-switch vs. -1% post-switch, p=.745). The regimen switch was not associated with reduced fracture risk: 1 year post-switch, the incidence risk ratios for regimen switchers relative to drug only switchers were 0.85, 95% CI 0.521.36, and 0.92, 95% CI 0.561.58, relative to nonswitchers).
Reducing the dosing demands of oral bisphosphonates from once-weekly to once-monthly decelerated but did not halt adherence failure. The regimen change did not translate to reduced fracture risk.
To cite this abstract, please use the following information:
Briesacher, Becky, Andrade, Susan, Harrold, Leslie R., Fouayzi, Hassan, Yood, Robert A.; Switching the Dose Regimen of Oral Bisphosphonates, Adherence and Fractures [abstract]. Arthritis Rheum 2009;60 Suppl 10 :861