Discontinuation of antiresorptive therapies: a comparison between 1998-2001 and 2002-2004 among osteoporotic women.
BACKGROUND
Studies having reported high rates of discontinuation of antiresorptive therapies (ART) may not reflect their actual use.


OBJECTIVE
We compared probability of discontinuation among women aged 70 yr or older with a diagnosis of osteoporosis or recent osteoporotic fracture having started ART (alendronate, risedronate, cyclical etidronate, raloxifene, nasal calcitonin) between 1998-2001 or 2002-2004.


METHODS
We constructed two cohorts of women using Régie de l'Assurance Maladie du Québec databases. Discontinuation was defined as a lapse of 30 d or longer after completion of a refill. Switching from one ART to another was allowed. Probability of discontinuation was estimated using Kaplan-Meier analysis. Multivariate Cox models were used to identify potential determinants of ART discontinuation over 1 yr.


RESULTS
After 1 yr, probability of discontinuation was slightly lower in the 2002-2004 cohort than the 1998-2001 cohort (52.2 vs. 57.5%; P < 0.001). This difference remained significant after adjusting for determinants [adjusted rate ratio (RR) 0.92, 95% confidence interval (CI) 0.87-0.98]. Significant determinants of ART discontinuation within 1 yr included bone mineral density testing (RR 0.77; CI 0.73-0.82) performed within 2 yr prior to initiation of therapy and having consulted more than two pharmacies (RR 1.15; CI 1.06-1.25) in the year before starting therapy. In the 2002-2004 cohort, when switching was allowed, women initiating a once-weekly regimen of alendronate or risedronate did not show a 1-yr risk of discontinuation different from women initiating daily regimens of the same drugs (RR 0.90; CI 0.82-1.00).


CONCLUSIONS
Even if new dosing regimens were introduced, discontinuation of ART among osteoporotic women remains high.
Blouin
Julie
J
Faculty, University of Montréal, Montréal, Québec, Canada H3C 3J7.
Dragomir
Alice
A
Ste-Marie
Louis-Georges
LG
Fernandes
Julio Cesar
JC
Perreault
Sylvie
S
D000368:Aged; D000369:Aged, 80 and over; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015233:Models, Statistical; D010024:Osteoporosis / Q000188:drug therapy*; D010342:Patient Acceptance of Health Care; D010349:Patient Compliance; D012044:Regression Analysis; D013997:Time Factors; D028761:Withholding Treatment
D050071:Bone Density Conservation Agents