RESEARCH - Risk factors for total knee arthroplasty in RA

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Mod Rheumatol. 2007;17(6):476-80. Epub 2007 Dec 20.

Risk factors for total knee arthroplasty in rheumatoid arthritis.

Momohara S, Inoue E, Ikari K, Kawamura K, Tsukahara S, Mochizuki T,

Toki H, Miyawaki M, Saito S, Hara M, Kamatani N, Yamanaka H, Tomatsu

T.

Department of Orthopaedic Surgery, Institute of Rheumatology, Tokyo

Women's Medical University, 10-22 Kawada, Shinjuku-ku, Tokyo,

162-0054, Japan.

We conducted a study to assess the predictive factors for total knee

arthroplasty (TKA) in a cohort of rheumatoid arthritis (RA) patients

recruited and followed prospectively for 5 years. A linked registry

study using information from a large observational cohort of RA

patients followed at the Institute of Rheumatology, Tokyo Women's

Medical University (IORRA) was done. Baseline routine clinical and

laboratory assessments were recorded. The data were analyzed using the

multivariate piecewise-linear (PL-) regression model; the model

initially included variables such as gender, age, duration of the

disease, visual analog scale (VAS) generated by physicians

(VAS-physician), patient-reported VAS for pain (VAS-pain), VAS for

general health (VAS-GH), disability level using the Japanese version

of the Health Assessment Questionnaire (J-HAQ), C-reactive protein,

erythrocyte sedimentation rate, rheumatoid factor (RF), and

hemoglobin. Of the 3945 patients registered at baseline, 955 (24.2%)

had pain or tenderness in their knee joints, and 114 (11.9%) had TKA

surgery in one or both knee joints. On PL- regression, the

variables with positive coefficients were J-HAQ, VAS-pain,

VAS-physician, and RF positive; advanced age was associated with a

reduced risk of TKA. The hazard ratios were: 0.920 for age >60 years;

2.64 for J-HAQ <1.5; 1.01 for J-HAQ >1.5; 1.47 for VAS-pain >6 (cm);

1.20 for VAS-physician >4 (cm); and 2.08 for RF positive. The

consistently predictive factors for TKA in RA were age, J-HAQ,

VAS-pain, VAS-physician, and RF positive. Age greater than 60 years

was associated with a decreased risk of TKA, while J-HAQ from 0 to

1.5, VAS-pain >6 (cm), and VAS-physician >4 (cm) were associated with

an increased risk for TKA surgery. These results suggest that, when

treating RA patients, physicians should pay particular attention to

pain complaints, the patient's daily activity level, and the RF factor

status.

PMID: 18084699

http://www.ncbi.nlm.nih.gov/pubmed/18084699

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