Table 2

Association of any bisphosphonate use with the risk of atypical femoral fracture

 CasesControlsAverage cumulative duration (days)Time since first bisphosphonate prescription (days)Model 1Model 2
n (%)n (%)Mean (SD)Mean (SD)OR (95% CI)OR (95% CI)
Use
 No use31 (70.5)197 (89.5)1 (ref.)1 (ref.)
 Ever use13 (29.6)23 (10.5)658 (538)1007 (708)3.63 (1.64 to 8.02)4.30 (1.55 to 11.9)
Timing
 No use31 (70.5)197 (89.5)1 (ref.)1 (ref.)
 Past use3 (6.8)6 (2.7)567 (569)1655 (772)3.16 (0.76 to 13.0)4.43 (0.62 to 31.9)
 Recent use1 (2.3)2 (0.9)299 (199)448 (87)4.89 (0.27 to 87.1)3.40 (0.03 to 384)
 Current use9 (20.5)15 (6.8)737 (546)835 (566)3.76 (1.51 to 9.36)4.29 (1.39 to 13.3)
Duration
 No use31 (70.5)197 (89.6)1 (ref.)1 (ref.)
 ≤1 year4 (9.1)8 (3.6)156 (100)675 (731)3.27 (0.92 to 11.7)2.55 (0.47 to 13.7)
 >1–≤3 year4 (9.1)12 (5.5)622 (213)967 (673)2.01 (0.58 to 6.92)1.68 (0.36 to 7.85)
 >3 year5 (11.4)3 (1.4)1485 (341)1587 (346)9.18 (2.12 to 38.9)31.9 (4.05 to 251)
 p for trend*0.0020.0007
Time since first bisphosphonate prescription
 No use31 (70.5)197 (89.6)1 (ref.)1 (ref.)
 <1 year3 (6.8)2 (0.9)142 (120)150 (130)10.0 (1.6 to 62.0)4.98 (0.56 to 44.2)
 1–<3 year4 (9.1)13 (5.9)446 (230)659 (180)1.94 (0.56 to 6.76)1.72 (0.36 to 8.34)
 ≥3 year6 (13.6)8 (3.6)1100 (582)1737 (540)4.71 (1.52 to 14.6)9.46 (2.17 to 41.3)
 p for trend†0.030.01
  • Model 1: Conditional logistic regression model adjusted for matching variables.

  • Model 2: Conditional logistic regression model adjusted for matching variables, smoking, alcoholism, BMI, previous fracture, kidney disease, malabsorption, stroke, dementia, rheumatoid arthritis, diabetes, epilepsy, Parkinson disease, thyroid disease, PPI (no use, ≤1 year, >1 year), anxiolytics, sedatives, antidepressants, antihypertensives, corticosteroids (no use, ≤1 year, >1year), raloxifene, hormone replacement therapy and thiazolidinediones.

  • *Modelled as the median duration of use in each category.

  • †Modelled as time in days since first bisphosphonate prescription (0 for no users).

  • BMI, body mass index; PPI, proton pump inhibitor.