Table 2 .

Parametric Weibull model assessment of the effect of bisphosphonate use on prosthesis survival, up to 15 years after surgery

Study group	Unadjusted models				Propensity adjusted models
	Hazard ratio (95% CI) for implant failure	Time ratio (95% CI) for implant survival	P value*		Hazard ratio (95% CI) for implant failure	Time ratio (95% CI) for implant survival	P value*
Total population (n=41 995)	0.41 (0.22 to 0.76)	2.54 (1.34 to 4.83)	0.004		0.54 (0.29 to 0.99)	1.96 (1.01 to 3.82)	0.047
Population diagnosed with osteoarthritis (n=34 336)	0.30 (0.13 to 0.70)	3.47 (1.44 to 8.37)	0.005		0.40 (0.17 to 0.93)	2.69 (1.07 to 6.73)	0.034
Population undergoing knee arthroplasty (n=18 726)	0.33 (0.12 to 0.88)	2.79 (1.12 to 6.91)	0.027		0.40 (0.15 to 1.07)	2.37 (0.94 to 6.01)	0.068
Population undergoing hip arthroplasty (n=23 269)	0.47 (0.24 to 0.94)	2.36 (1.07 to 5.21)	0.033		0.64 (0.32 to 1.28)	1.71 (0.74 to 3.94)	0.20

P values apply to both time ratios and hazard ratios.