Characteristics of patients with rheumatoid arthritis undergoing primary total joint replacement: A 14-year trend analysis (2004–2017)

Figures & data

Table 1. Patient characteristics at the time of surgery.

		Year of surgery
	Total	2004–2010	2011–2017	p value
	(n = 403)	(n =234)	(n =169)
Female, %	83	85	82	0.498
Age at surgery, years	65 (58, 71)	63 (57, 69)	66 (60, 73)	0.005
Age at RA onset, years	49 (39, 59)	48 (37, 57)	51 (41, 61)	0.013
Time from RA onset to TJR, years	14 (8, 22)	14 (8, 22)	14 (8, 22)	0.619
Elderly-onset RA, %	23	20	28	0.042
Surgery site, %				0.024
Knee	66	67	64
Hip	22	24	19
Elbow	10	8	13
Shoulder	1	0	3
Ankle	1	1	1
Use of methotrexate, %	63	56	71	0.003
Use of biologics, %	33	26	44	<0.001
Use of glucocorticoids, %	52	55	47	0.106
CRP, mg/dl	0.56 (0.17, 1.69)	0.88 (0.29, 2.22)	0.30 (0.07, 0.95)	<0.001
CRP ≤0.3 mg/dl, %	37	27	50	<0.001
Osteophytes on radiograph, %	72	71	75	0.430

Data are presented as median values (interquartile range) or percentage.

RA: rheumatoid arthritis; TJR: total joint replacement; CRP: C-reactive protein.

Figure 1. (a) Time trends in numbers of total joint replacements and (b) time from rheumatoid arthritis onset to total joint replacement. *The Jonkheere–Terpstra trend test.

Figure 2. Time trends in (a) age, (b) proportion of patients with elderly-onset rheumatoid arthritis (EORA), (c) serum C-reactive protein (CRP) levels, (d) proportion of patients with CRP ≤0.3 mg/dl, (e) methotrexate use, (f) biologic use, (g) glucocorticoid use, and (h) osteophytes on radiograph. Data are presented as mean values or percentage. *The Jonkheere–Terpstra trend test; †The Cochran–Armitage trend test.

Table 2. Patient characteristics stratified by serum C-reactive protein (CRP) levels.

	CRP ≤0.3 mg/dl	CRP >0.3 mg/dl	p value
	(n =149)	(n =254)
Female, %	82	84	0.782
Age at surgery, years	64 (58, 71)	65 (58, 70)	0.971
Age at RA onset, years	49 (35, 59)	49 (40, 59)	0.260
Elderly-onset RA, %	24	23	0.806
Surgery site, %			0.001
Knee	58	71
Hip	23	22
Elbow	16	6
Shoulder	3	0
Ankle	0	1
Use of methotrexate, %	65	61	0.457
Use of biologics, %	43	28	0.003
Use of glucocorticoids, %	48	54	0.302
Osteophytes on radiograph, %	82	66	0.001

Data are presented as median values (interquartile range) or percentage.

RA: rheumatoid arthritis.

Figure 3. Time from rheumatoid arthritis (RA) onset to total joint replacement (TJR) stratified by (a) serum C-reactive protein (CRP) levels, (b) osteophytes on radiograph, (c) age at RA onset, and (d) surgery site. The box plot shows the median value (central line) and 25th and 75th percentiles (horizontal lines); whiskers indicate minimum and maximum values; and circles represent outliers. Statistical comparison was performed using the Mann–Whitney U test. EORA: elderly-onset RA; YORA: younger-onset RA.

Table 3. Factors associated with time from rheumatoid arthritis (RA) onset to total joint replacement.

Variables	B (95% CI)	SE B	β	p-value
CRP
≤0.3 mg/dL	2.44 (0.45, 4.43)	1.01	0.11	0.016
>0.3 mg/dL	Reference
Age at RA onset
EORA	–12.06 (–14.28, –9.84)	1.13	−0.47	<0.001
YORA	Reference
Surgery site
Knee/hip	–2.26 (–5.22, 0.69)	1.50	−0.07	0.133
Others	Reference
Osteophytes on radiograph
Yes	3.55 (1.41, 5.68)	1.09	0.15	0.001
No	Reference

B: partial regression coefficient; CI: confidence interval; SE: standard error; β: standardized partial regression coefficient; CRP: C-reactive protein; EORA: elderly-onset RA; YORA: younger-onset RA.