Table 2.

Incidence rates of hip fracture among women variably compliant with bisphosphonate therapy for two or three years

a. Two years of prior bisphosphonate therapy
MPR<50% N=8878 women	MPR≥66% N=9063 women		MPR≥80% N=7505 women
N, person-years	N, person-years	N, person-years	N, person-years	N, person-years
Rate off BP	Rate off BP	Rate on BP	Rate off BP	Rate on BP
	P value**	P value**	P value**	P value**
117, 11185	25, 2966	46, 9850	13, 2124	41, 8489
10.46	8.43*	4.67*	6.12	4.83
Referent	P=0.33**	P<0.0001**	P=0.04**	P<0.0001**
b. Three years of prior bisphosphonate therapy
MPR < 50%, N=5385 women	MPR≥66%, N=4556 women		MPR≥80%, N=3715 women
N, person-years	N, person-years	N, person-years	N, person-years	N, person-years
Rate off BP	Rate off BP	Rate on BP	Rate off BP	Rate on BP
	P value**	P value**	P value**	P value**
58, 5697	8, 1125	20, 4175	5, 789	18, 3523
10.18	7.11	4.79	6.34	5.11
Referent	P=0.34**	P=0.003**	P=0.30**	P=0.009**

BP=bisphosphonate; MPR=medication possession ratio at end of 2 or 3 year eligibility period (defines study baseline) Hip fracture rates expressed per 1,000 person years

^*rates are significantly different at p=0.016 between persons on and off-drug within this MPR group but are not significantly different for the other three rate comparisons

^**p value compares fracture rate in this column to fracture rate among women with MPR<50% in the same row