Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose :
Knee replacement (KR) surgery for osteoarthritis (OA) provides improvement in symptoms and function. Whether these improvements translate into survival benefit has been unclear, likely related to selection of healthier patients for surgery, exclusion of the post-operative immortal time, and inadequate length of follow-up in prior studies. The purpose of this study was to determine risk of mortality related to KR by comprehensive adjustment for confounders using a propensity-score (PS) matched cohort approach and long follow-up.
Methods :
Participants ages 50-89 years with a diagnosis of knee OA (from Read Codes) were included from The Health Improvement Network (THIN), an electronic medical records database representative of the UK general population. High risk subjects who are less likely to be surgical candidates (BMI>40, history of joint infection, high risk cancers (pancreatic, esophageal, gastric or other metastatic), end-stage renal disease on dialysis, use of nasal cannula oxygen, or DMARD therapy) were excluded. PS for KR was calculated using logistic regression with KR as the dependent variable and the confounders listed in the table as independent variables, that reflect indications for KR and risk for poor outcomes. One year cohort-accrual blocks were created, and each KR subject was matched 1:1 by PS with a non-KR subject. Follow-up started from the index date, which was the date of surgery for KR subjects and a random date within the cohort accrual block for non-KR subjects, and continued until death or censoring. We examined the association of KR with mortality by calculating crude incidence rates (IR) and Hazard ratios (HR) using Cox proportional hazard regression. We also examined the association stratified by age category (<70years, ≥70years) as well as within percentile categories of the PS.
Results :
There were 14,675 pairs of subjects with knee OA (mean age 71yrs; 57% women; mean BMI 29kg/m2) in the PS-matched cohort. The follow-up years were 63769 and 60582 for matched KR and non-KR subjects, respectively. Overall there was 31% lower risk of mortality among subjects with KR (HR 0.69, 95% CI 0.64-0.75). The lower risk remained in subjects ≥70 years but no such relation was noted in subjects <70 years (table). The crude IR for mortality among KR subjects decreased as PS percentile category increased, while no such trend was noted for the non-KR subjects. Mortality risk was lowest (HR 0.29, 95% CI 0.13-0.63) in the highest PS percentile (>98%) category (table).
Conclusion :
We found KR to be protective for mortality risk among subjects ≥70 years and among those with the highest propensity for KR. Although a protective effect of KR cannot be ruled out, there likely remains confounding by indication despite comprehensive adjustment of covariates. Patients, physicians, and surgeons consider additional factors in performing KRs that are not adequately captured within administrative databases.
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Table: Association of Knee Replacement Surgery and Mortality Risk , stratified by age and by percentiles of propensity scores, in a propensity-score matched cohort of men and women with knee osteoarthritis
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|
Score*
|
No. of Pairs
|
KR
|
Non-KR
|
HR(95% CI)
|
|||||
|
Death
|
Followup-years
|
IR
|
Death
|
Followup-years
|
IR
|
||||
|
Overall
|
– |
14,675 |
1233 |
63769.3 |
0.019 |
1636 |
60581.7 |
0.027 |
0.69 (0.64-0.75) |
|
Age < 70 years
|
0.057 |
6,553
|
270
|
29413.0
|
0.009
|
291
|
30372.3
|
0.010
|
1.00 (0.78-1.31) |
|
Age 70-90 years
|
0.055
|
7,911
|
963
|
34356.3
|
0.028
|
1345
|
30209.4
|
0.045 |
0.59 (0.52-0.68) |
|
|
|
|
|
|
|
|
|
|
|
|
Propensity-score percentile category
|
|
|
|
|
|
|
|
|
|
|
<2% |
0.005 |
293 |
40 |
1391.9 |
0.029 |
50 |
1306.9 |
0.038 |
0.76 (0.48-1.21) |
|
2%-10% |
0.012 |
1174 |
129 |
5536.4 |
0.023 |
148 |
5231.2 |
0.028 |
0.78 (0.60-1.03) |
|
10%-20% |
0.019 |
1467 |
153 |
6703.1 |
0.023 |
175 |
6280.3 |
0.028 |
0.77 (0.60-0.98) |
|
20%-30% |
0.025 |
1468 |
142 |
6565.0 |
0.022 |
165 |
6289.7 |
0.026 |
0.76 (0.59-0.98) |
|
30%-40% |
0.032 |
1467 |
125 |
6510.3 |
0.019 |
157 |
6170.1 |
0.025 |
0.78 (0.60-1.02) |
|
40%-50% |
0.040 |
1468 |
110 |
6255.3 |
0.018 |
152 |
6088.7 |
0.025 |
0.74 (0.56-0.97) |
|
50%-60% |
0.049 |
1467 |
126 |
6453.4 |
0.019 |
151 |
6130.2 |
0.025 |
0.83 (0.63-1.08) |
|
60%-70% |
0.060 |
1468 |
118 |
6314.7 |
0.019 |
168 |
5997.9 |
0.028 |
0.60 (0.46-0.80) |
|
70%-80% |
0.075 |
1467 |
95 |
6301.0 |
0.015 |
149 |
6074.4 |
0.025 |
0.57 (0.42-0.76) |
|
80%-90% |
0.097 |
1468 |
106 |
6065.1 |
0.017 |
174 |
5639.8 |
0.031 |
0.52 (0.40-0.68) |
|
90%-98% |
0.136 |
1174 |
79 |
4546.6 |
0.017 |
117 |
4350.9 |
0.027 |
0.65 (0.47-0.90) |
|
>98% |
0.208 |
293 |
10 |
1120.9 |
0.009 |
30 |
1021.6 |
0.029 |
0.29 (0.13-0.63) |
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* Mean propensity score within the percentile
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Confounders used for calculation of propensity score: 1) OA severity and duration 2) General (age, gender, BMI, socio-economic status); 3) Comorbidities (hypertension, diabetes (including severity), hyperlipidemia, ischemic heart disease (including severity), heart failure, atrial fibrillation, stroke, dementia/cognitive impairment, depression, seizure disorder, peripheral vascular disease, venous thrombo-embolism, chronic obstructive lung disease, lung infection, renal disease, liver disease, cancers except skin cancer , cellulitis, falls, hip fracture, anemia and peptic ulcer disease ); 4) Habits (smoking status and alcohol use); 5) Health status (number of GP visits and hospitalization, albumin level); and 6) Medication use (Non-steroidal anti-inflammatory medications, opioid or non-opioid analgesics, anti-hypertensive, cholesterol lowering, insulin/oral hypoglycemic, bisphosphonates, raloxifene, strontium, glucocorticoids and anti-epileptics);
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Disclosure:
D. Misra,
None;
T. Neogi,
None;
N. Lu,
None;
D. T. Felson,
None;
T. Einhorn,
None;
H. K. Choi,
Takeda,
5,
AstraZeneca,
5;
J. Maxwell,
None;
Y. Zhang,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/mortality-after-knee-replacement-surgery-for-osteoarthritis-in-a-population-based-propensity-score-matched-cohort/