Session Information
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: In the US, the annual rate of TKRs in people 65 years or older increased almost 9-fold between 1979 and 2006, with similar if not greater growth in younger age groups. There is increasing debate regarding the appropriate utilization of TKRs. We examined change in pain and function, quality of life (QOL), and patient satisfaction at 6-month post-surgery stratified by their pre-surgery pain and function status.
Methods: We used data from the Function and Outcomes Research for Comparative Effectiveness in TJR (FORCE-TJR), a national cohort of TJR patients of more than 150 surgeons in 22 sites nationwide. Participants had: primary, unilateral TKRs indicated by osteoarthritis; surgeries between April 2011 and May 2014; completed pre-operative Knee Injury and Osteoarthritis Outcome Score (KOOS) including QOL items and Short-Form 36-item (SF-36) functional health survey; and the respective 6-month post-operative surveys, with satisfaction measured by Self Evaluated Transitions items. We classified patients as having high or low pain (KOOS Pain<70 vs. ≥70), and low or high physical function (SF-36 PCS <40 vs. ≥40) and grouped then as follows: 1) Low pain-High function (LP-HF), 2) Low pain-Low function (LP-LF), 3) High pain-High function (HP-HF), and 4) High pain-Low function (HP-LF). Change from baseline to 1-year post-surgery pain and function scores were calculated. Cohen’s unadjusted standardized differences in absolute post-op scores accounting for pooled SD were calculated with LP-HF as referent group.
Results: This study included 4,563 participants: 5% pre-op LP-HF, 20% either HP or LF, and 75% both HP-LF. By 6-month post-op (Table), in Group 1, 85% remained the same but 4% became much worse among people with pre-op LP-HF: in Group 4, 18% remained the same and 52% achieved much improvement among people with pre-op HP-LF. Mean change (SD) in 6-month KOOS pain score in LP-HF group was 8.3 (14.6) compared with 37.2 (19.7) in the HP-LF group. Patients in LP-HF had the near highest absolute mean (SD) post-op pain score (88.9 (13.0)) and the HP-LF group the lowest (79.9 (17.3)); the unadjusted standardized effect size was 0.59. Similarly, the mean change in PCS function was 2.6 (7.8) in the LP-HF group, and was 11.9 (9.0) in the HP-LF group. The LP-HF group had the highest absolute mean 6-month post-surgery function of 50.0 (7.4) while the HP-LF group had the lowest score of 42.0 (9.5); the unadjusted standardized effect size was 0.94. The groups reported similar satisfaction, but QOL items indicated better QOL among the pre-surgery LP-HF than the HP-LF groups.
Conclusion: While TKR patients with low pain and high function pre-op achieved the smallest mean change in pain and function, they reported better absolute outcomes at 6-months. The majority of TKR patients with high pain and poor function achieved the greatest mean improvement in pain and function.
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Table. 6 Month-Change in Pain and Function by Pre-Operative Pain and Function Status |
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Characteristics |
Group 1 Low Pain High Function n=234 (5%) |
Group 2 Low Pain Low Function n=173 (4%) |
Group 3 High Pain High Function n=718 (16%) |
Group 4 High Pain Low Function n=3288 (75%) |
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Pain & Function Status 6-mth Post-KR |
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Remained in Same Classification Group |
85% |
25% |
11% |
18% |
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Optimal Improvement -> (to Low Pain-High Function Group) |
NA |
65% |
79% |
52% |
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Worst Decline-> (to High Pain-Low Function Group) |
4% |
6% |
7% |
NA |
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Other Changes |
9% |
4% |
3% |
30% |
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6-month Change in Pain & Symptoms |
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Pain, KOOS Mean (SD) – Pre |
80.7 (7.9) |
79.5 (7.6) |
53.7 (11.0) |
42.7 (11.6) |
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Pain, KOOS Mean (SD) – Post |
88.9 (13.0) |
89.6 (11.3) |
84.2 (14.8) |
79.9 (17.3) |
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Unadjusted 6-mth Change Mean (SD) |
8.3 (14.6) |
10.2 (12.9) |
30.5 (16.6) |
37.2 (19.7) |
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Unadjusted Standardized Differences relative to Pooled SD** |
REF |
0.06 |
0.34 |
0.59 |
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6-month Change in Function |
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Function, SF36 PCS, Mean (SD)- Pre |
47.4 (4.7) |
34.0 (4.4) |
44.5 (3.6) |
30.1 (6.0) |
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Function, SF36 PCS, Mean (SD)- Post |
50.0 (7.4) |
44.1 (8.5) |
49.3 (7.0) |
42.0 (9.5) |
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Change over 6 months Mean (SD) |
2.6 (7.8) |
10.2 (7.8) |
4.8 (7.0) |
11.9 (9.0) |
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Unadjusted Standardized Differences relative to Pooled SD** |
REF |
0.74 |
0.10 |
0.94 |
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6-mth Post-TKR Satisfaction using Self-Evaluated Transitions |
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Better Health compared to 1 year ago- |
60% |
54% |
61% |
63% |
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More Capable everyday physical activity |
79% |
80% |
82% |
82% |
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More able to accomplish daily work |
78% |
78% |
77% |
78% |
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Less often bothered by emotional problem |
47% |
43% |
47% |
52% |
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Better Health compared to before surgery |
61% |
57% |
63% |
64% |
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Pre- and Post-TKR QoL Issues |
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Awareness Knee Problem Daily/Constantly-Pre* |
86% |
92% |
98% |
99% |
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Daily/Constantly-Post |
46% |
52% |
54% |
62% |
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General Difficulty with Knee |
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NONE-Pre* |
5.9% |
4.0% |
0.7% |
0.2% |
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NONE-Post |
50% |
38% |
35% |
26% |
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* For Descriptive Purposes Only **Cohen’s d http://www.uccs.edu/~lbecker/: effect size: 0.2-small, 0.5-medium, 0.8-large |
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To cite this abstract in AMA style:
Nguyen USDT, Ayers D, Li W, Harrold L, Franklin PD. 6-Month Change in Pain and Function By Pre-Surgery Pain and Function Among Patients Selected for Total Knee Replacement in the United States [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/6-month-change-in-pain-and-function-by-pre-surgery-pain-and-function-among-patients-selected-for-total-knee-replacement-in-the-united-states/. Accessed .« Back to 2015 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/6-month-change-in-pain-and-function-by-pre-surgery-pain-and-function-among-patients-selected-for-total-knee-replacement-in-the-united-states/