Table 4.

Hazard ratios for in-hospital mortality by intervention period

Variable	HR (95% CI)
	Unadjusted	Adjusted
Period (post v. pre)	0.73 (0.62–0.87)	0.68 (0.57–0.81)
Age, yr	—	1.04 (1.03–1.05)
Sex (male v. female)	—	2.05 (1.73–2.44)
Presence of comorbidities (≥ 1 v. 0)	—	4.02 (3.34–4.84)
Procedure type (internal fixation v. arthroplasty)	—	1.66 (1.37–2.01)
Centred year of surgery (last v. first)	—	0.91 (0.83–1.01)

CI = confidence interval; HR = hazard ratio.