Misra Devyani, Lu Na, Felson David, Choi Hyon K, Seeger John, Einhorn Thomas, Neogi Tuhina, Zhang Yuqing
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, USA.
Ann Rheum Dis. 2017 Jan;76(1):140-146. doi: 10.1136/annrheumdis-2016-209167. Epub 2016 May 17.
The relation of knee replacement (KR) surgery to all-cause mortality has not been well established owing to potential biases in previous studies. Thus, we aimed to examine the relation of KR to mortality risk among patients with knee osteoarthritis (OA) focusing on identifying biases that may threaten the validity of prior studies.
We included knee OA subjects (ages 50-89 years) from The Health Improvement Network, an electronic medical records database in the UK. Risk of mortality among KR subjects was compared with propensity score-matched non-KR subjects. To explore residual confounding bias, subgroup analyses stratified by age and propensity scores were performed.
Subjects with KR had 28% lower risk of mortality than non-KR subjects (HR 0.72, 95% CI 0.66 to 0.78). However, when stratified by age, protective effect was noted only in older age groups (>63 years) but not in younger subjects (≤63 years). Further, the mortality rate among KR subjects decreased as candidacy (propensity score) for KR increased among subjects with KR, but no such consistent trend was noted among non-KR subjects.
While a protective effect of KR on mortality cannot be ruled out, findings of lower mortality among older KR subjects and those with higher propensity scores suggest that prognosis-based selection for KR may lead to intractable confounding by indication; hence, the protective effect of KR on all-cause mortality may be overestimated.
由于既往研究存在潜在偏倚，膝关节置换术（KR）与全因死亡率之间的关系尚未明确确立。因此，我们旨在研究KR与膝骨关节炎（OA）患者死亡风险之间的关系，重点是识别可能威胁既往研究有效性的偏倚。
我们纳入了来自英国电子病历数据库“健康改善网络”的膝OA受试者（年龄50 - 89岁）。将KR受试者的死亡风险与倾向评分匹配的非KR受试者进行比较。为探讨残余混杂偏倚，进行了按年龄和倾向评分分层的亚组分析。
KR受试者的死亡风险比非KR受试者低28%（HR 0.72，95%CI 0.66至0.78）。然而，按年龄分层时，仅在老年组（>63岁）观察到保护作用，而在年轻受试者（≤63岁）中未观察到。此外，KR受试者的死亡率随着KR候选资格（倾向评分）在KR受试者中的增加而降低，但在非KR受试者中未观察到这种一致趋势。
虽然不能排除KR对死亡率有保护作用，但老年KR受试者和倾向评分较高者死亡率较低的结果表明，基于预后的KR选择可能导致难以处理的指征性混杂；因此，KR对全因死亡率的保护作用可能被高估。
