Original Research

Rheumatoid Arthritis vs Osteoarthritis: Comparison of Demographics and Trends of Joint Replacement Data from the Nationwide Inpatient Sample

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Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease that causes joint deterioration, leading to pain, disability, systemic complications, short lifespan, and decline in quality of life.1-3 The deterioration primarily affects the synovial membranes of joints, causing arthritis and resulting in extra-articular sequelae such as cardiovascular disease,4 pulmonary disease,5 and increased infection rates.3,6 RA is the most prevalent inflammatory arthritis worldwide and affects up to 50 cases per 100,000 in both the US and northern Europe.2,7-9 Although the gold standard of care for these patients is medical management with immunosuppressant drugs such as disease-modifying anti-rheumatic drugs (DMARDs), total joint arthroplasty (TJA) remains an important tool in the management of joint deterioration in such patients.

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are common procedures utilized to treat disorders that cause joint pain and hindered joint mobility, including osteoarthritis (OA) and RA. Given the aging population, the amount of TKAs and THAs performed in the US has consistently increased each year, with the vast majority of this increase composed of patients with OA.10 As a result, previous studies investigated the trends and outcomes of these procedures in patients with OA, but relatively less is known about the outcomes and trends of patients with RA undergoing the same surgeries.

Given that RA is a fundamentally different condition with its own pathological characteristics, an understanding of how these differences may impact postoperative outcomes in patients with RA is important. This study aims to present a comparative analysis of the trends and postoperative outcomes between patients with RA and OA undergoing TKA and THA (Figure 1, Tables 1 and 2).

Table 1. Demographics of Total Knee Arthroplasty Patients Based on Primary Diagnosis of Osteoarthritis

OA

RA

Total

P Value

No.

Percent

No.

Percent

No.

Percent

(RA vs OA)

Age group

<.0001

<64 years

295,637

42.42

11,325

48.90

306,962

42.63

65 to 79 years

329,034

47.22

10,055

43.42

339,089

47.09

≥80 years

72,197

10.36

1780

7.69

73,977

10.27

Gender

<.0001

Male

259,192

37.19

4887

21.12

264,079

36.68

Female

435,855

62.54

18,248

78.88

454,103

63.07

Race

<.0001

White

468,632

67.25

14,532

77.18

483,164

67.10

Black

39,691

5.7

2119

11.25

41,810

5.81

Hispanic

28,573

4.1

1395

7.41

29,968

4.16

Other

21,306

3.06

783

4.16

22,089

3.07

Region of hospital

<.0001

Northeast

112,031

16.08

3417

14.75

115,448

16.03

Midwest

192,595

27.64

5975

25.80

198,570

27.58

South

257,855

37

9422

40.68

267,277

37.12

West

134,387

19.28

4346

18.77

138,733

19.27

Location/teaching status of hospital

<.0001

Rural

86,321

12.39

2709

11.79

89,030

12.36

Urban non-teaching

333,043

47.79

10,905

47.46

343,948

47.77

Urban teaching

273,326

39.22

9363

40.75

282,689

39.26

Hospital location

.0024

Rural

86,321

12.39

2709

11.79

89,030

12.36

Urban

606,369

87.01

20,268

88.21

626,637

87.03

Hospital teaching status

<.0001

Teaching

409,465

58.76

13,275

57.78

422,740

58.71

Non-teaching

283,225

40.64

9702

42.22

292,927

40.68

Comorbidities

Obstructive sleep apnea

65,342

9.38

1946

8.40

67,288

9.35

<.0001

Diabetes

147,292

21.14

4289

18.52

151,581

21.05

<.0001

Obesity

129,277

18.55

3730

16.11

133,007

18.47

<.0001

Abbreviations: OA, osteoarthritis; RA, rheumatoid arthritis.

Table 2. Demographics of Total Hip Arthroplasty Patients Based on Primary Diagnosis of Osteoarthritis or Rheumatoid Arthritis

OA

RA

Total

P Value

No.

Percent

No.

Percent

No.

Percent

(RA vs OA)

Age group

<.0001

<64 years

133,645

45.18

4679

48.02

138,324

45.27

65 to 79 years

123,628

41.8

3992

40.97

127,620

41.77

≥80 years

38,513

13.02

1073

11.01

39,586

12.96

Gender

<.0001

Male

129,708

43.85

2457

25.24

132,165

43.26

Female

165,010

55.79

7278

74.76

172,288

56.39

Race

<.0001

White

207,005

69.98

6322

80.08

213,327

69.82

Black

15,505

5.24

771

9.77

16,276

5.33

Hispanic

6784

2.29

522

6.61

7306

2.39

Other

7209

2.44

280

3.55

7489

2.45

Region of hospital

<.0001

Northeast

58,525

19.79

1683

17.27

60,208

19.71

Midwest

79,040

26.72

2446

25.10

81,486

26.67

South

95,337

32.23

3716

38.14

99,053

32.42

West

62,884

21.26

1899

19.49

64,783

21.20

Location/teaching status of hospital

.0065

Rural

30,954

10.46

993

10.26

31,947

10.46

Urban non-teaching

133,061

44.99

4245

43.87

137,306

44.94

Urban teaching

130,150

44

4439

45.87

134,589

44.05

Hospital location

.4098

Rural

30,954

10.46

993

10.26

31,947

10.46

Urban

263,211

88.99

8684

89.74

271,895

88.99

Hospital teaching status

.0077

Teaching

159,313

53.86

5108

52.78

164,421

53.82

Non-teaching

134,852

45.59

4569

47.22

139,421

45.63

Comorbidities

Obstructive sleep apnea

19,760

6.68

573

5.88

20,333

6.65

.0028

Diabetes

41,929

14.18

1325

13.60

43,254

14.16

.1077

Obesity

38,808

13.12

1100

11.29

39,908

13.06

<.0001

Abbreviations: OA, osteoarthritis; RA, rheumatoid arthritis

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