Risk of joint replacement surgery in Taiwanese female adults with systemic lupus erythematosus: a population-based cohort study

Table 2 Incidence rates and incidence rate ratios of surgery for systemic lupus erythematosus cohort and comparison cohort (N = 3462)

Type of surgery (ICD-9-CM)	systemic lupus erythematosus cohort			comparison cohort			IRR (95% CI)	aIRR (95% CI)
	systemic lupus erythematosus cohort			comparison cohort			P value	P value
	No. of patients	Person-years	IR	No. of patients	Person-years	IR	P value	P value
THR (81.51)	12	3643.4	329.36	7	19,080.9	36.68	8.98 (3.53–22.80) < 0.001	6.47 (2.43–17.22) < 0.001
TKR (81.54)	6	3659.9	163.94	15	19,042.0	78.77	2.08 (0.81–5.36) 0.129	1.81 (0.69–4.75) 0.227

aIRR adjusted incidence rate ratio, IR incidence rate, THR total hip replacement surgery, TKR total knee replacement surgery
aIRRs were adjusted for obesity, fracture of the lower limb, socioeconomic status, and geographic region

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