Table 5.

Fracture rates as function of duration of treatment with alendronate in patients with medication possession ratio of 80% or more

	Treatment duration (years)
	0-5	5-10	>10
Subtrochanteric and femoral shaft fracture
No of patients	566	157	19
Patient years	163 590	49 399	4600
Incidence rate* (per 1000 person years)	3.45 (3.18 to 3.76)	3.18 (2.70 to 3.72)	4.13 (2.49 to 6.45)
Case-control odds ratios (table 3)	Reference	1.04	0.70
Number needed to treat†	Reference	—	193
Number needed to harm†	Reference	1449	—
Hip fracture
No of patients	3289	562	66
Patient years	160 556	47 269	4362
Incidence rate* (per 1000 person years)	20.48 (19.79 to 21.20)	11.89 (10.92 to 12.91)	15.13 (11.70 to 19.25)
Case-control odds ratios (table 4)	Reference	0.74	0.74
Number needed to treat†	Reference	38	38
Number needed to harm†	Reference	—	—

*Incidence rate for comparison based on observed absolute event rates. Lower incidence rate does not necessarily imply lower odds ratios as patients with different duration of use might differ on risk characteristics.

†Number needed to treat and number needed to harm express number of patients who must be treated for another additional five years to prevent (number needed to treat) or add (number needed to harm) one additional fracture respectively. Comparator is treatment for 0-5 years. Case-control odds ratio that contribute to calculation of these is age and sex matched metric adjusted for comorbid conditions and comedications (see tables 2 and 3 for details).