BACKGROUND Knee osteoarthritis is a common, chronic condition and main contributor to global disability. Total knee arthroplasty (TKA) is the most successful treatment for end-stage knee osteoarthritis. It is assumed that in the field of surgery, there is a relationship between hospital volume and health outcomes and that higher hospital volume results in better health outcomes. As a consequence, minimum volume thresholds have been implemented in Germany for various procedures, including TKA (50 procedures per year). To date, it is unclear whether minimum volume thresholds truly result in better outcomes. The objective of this study will be to quantify the relationship between hospital volume and patient-relevant outcomes in patients undergoing TKA. METHODS We will include published or unpublished (cluster-) randomized controlled trials and prospective or retrospective cohort studies that involve patients with primary and/or revision TKA, report at least two different hospital volumes and report at least one patient-relevant outcome. To identify studies, we will systematically search (from inception onwards) PubMed/MEDLINE, Embase, CENTRAL, and CINAHL, as well as trial registers, conference proceedings, and reference lists. We will also contact experts in the field. Study selection and data extraction will be performed by two reviewers independently. The primary outcome will be rate of early revision. Secondary outcomes will include rate of revision > 1 year, mortality, length of stay, readmission rate, surgical complications, adverse events and health-related quality of life. We will assess the risk of bias of the included studies using ROBINS-I or the Cochrane risk of bias tool. Both a linear and a non-linear dose-response meta-analyses will be performed. We will use the GRADE approach to evaluate our confidence in the cumulative evidence. We will incorporate patients' needs, goals and preferences into our recommendations by consulting three focus groups, each consisting of eight participants. DISCUSSION The findings of our systematic review will probably be limited by the design of the included studies. We do not expect to identify any (cluster-) randomized controlled trials that meet our inclusion criteria. Therefore, the best available evidence included in our systematic review will most likely consist of cohort studies only. We anticipate that the results of this study will inform future health policy decisions in Germany regarding the minimum volume threshold for TKA. Systematic review registration: PROSPERO CRD42019131209.

中文翻译：

---

全膝关节置换术中的医院容量与结果关系：系统评价和非线性剂量反应荟萃分析方案。

背景技术膝骨关节炎是一种常见的慢性疾病，也是导致全球残疾的主要原因。全膝关节置换术（TKA）是治疗终末期膝骨关节炎最成功的方法。假设在外科领域，医院数量和健康结果之间存在关系，并且医院数量越高，健康结果越好。因此，德国对各种手术实施了最低手术量阈值，包括 TKA（每年 50 次手术）。迄今为止，尚不清楚最小交易量阈值是否真正能带来更好的结果。本研究的目的是量化接受 TKA 的患者的医院容量与患者相关结果之间的关系。方法 我们将纳入已发表或未发表的（集群）随机对照试验以及涉及初次和/或翻修 TKA 患者的前瞻性或回顾性队列研究，报告至少两项不同的医院数据，并报告至少一项与患者相关的结果。为了识别研究，我们将系统地检索（从一开始）PubMed/MEDLINE、Embase、CENTRAL 和 CINAHL，以及试验登记册、会议记录和参考文献列表。我们还将联系该领域的专家。研究选择和数据提取将由两名评审员独立进行。主要结果是早期翻修率。次要结局包括 > 1 年的翻修率、死亡率、住院时间、再入院率、手术并发症、不良事件和健康相关的生活质量。我们将使用 ROBINS-I 或 Cochrane 偏倚风险工具评估纳入研究的偏倚风险。将进行线性和非线性剂量反应荟萃分析。我们将使用 GRADE 方法来评估我们对累积证据的信心。我们将通过咨询三个焦点小组（每个小组由八名参与者组成），将患者的需求、目标和偏好纳入我们的建议中。讨论 我们的系统评价的结果可能会受到纳入研究的设计的限制。我们不希望找到任何符合我们纳入标准的（集群）随机对照试验。因此，我们的系统评价中包含的最佳可用证据很可能仅包含队列研究。我们预计这项研究的结果将为德国未来有关全膝关节置换手术最小体积阈值的卫生政策决策提供信息。系统审评注册号：PROSPERO CRD42019131209。