Abstract：
OBJECTIVE: Blood transfusion is a common perioperative complication of primary total knee arthroplasty (TKA) that can lead to adverse outcomes, prolonged hospital stays, and increased medical costs. The purpose of our study was to explore the risk factors for blood transfusion and to establish whether operation duration is independently related to blood transfusion risk in patients undergoing primary TKA after adjusting for other covariates.
METHODS: This was a secondary analysis of data from a retrospective cohort study involving patients who underwent primary TKA in Singapore. The patients\' baseline data, comorbidity, and surgical characteristics were collected. The independent variable was operation duration and the dependent variable was blood transfusion events. Patients were divided into three groups according to operation durations (90 and 120 min). Univariate logistic regression was used to explore the risk factors associated with blood transfusion after primary TKA. Multivariate analysis was used to assess the independent effect of operation duration on blood transfusion risk after adjusting for other covariates. Additionally, we performed subgroup analyses to identify specific groups, test the robustness of the relationships, and explore whether there were interactions between the different variables. Furthermore, restricted cubic splines (RCS) were used to identify the relationship between the two variables.
RESULTS: A total of 2,562 patients were included in the study, of whom 136 (5.61%) had a transfusion event. Operation durations were 95.55 ± 36.93 and 83.86 ± 26.29 min for blood transfused and non-transfused patients, respectively. Univariate logistic regression analysis showed that age, BMI, ASA status, Hb level, OSA, CHF, creatinine level > 2 mg/dL, and anaesthesia type were risk factors for blood transfusion. After adjusting for all covariates, multivariate logistic regression models showed that operation duration was positively associated with blood transfusion risk (odds ratio [OR] = 1.87, 95% CI = 1.174-2.933, P = 0.007). Compared to patients with an operation duration of less than 90 min, those with an operation duration of more than 120 min had a 2.141-fold increased risk of blood transfusion (OR = 2.141, 95% CI = 1.035-4.265, P = 0.035). Stratified analysis results showed that the association persisted in patients aged > 50 years, Chinese, BMI > 30 kg/m 2, Hb level > 11 g/dL, ASA status levels 2 and 3, general anaesthesia, and unilateral primary TKA. A non-linear (P-non-linear = 0.30) and J-shaped relationship was identified. The risk of transfusion increased as the operation duration decreased or exceeded the inflection point (73.2 min).
CONCLUSIONS: Our study demonstrated a non-linear and J-shaped relationship between operation duration and blood transfusion events in patients undergoing primary TKA. Blood transfusion risk was the lowest when the operation duration was 73.2 min. A shorter operation duration implies irregular surgical procedures and incomplete intraoperative haemostasis, leading to increased perioperative blood loss and blood transfusion. These results will be useful for clinical decision-making.
METHODS: This was a secondary analysis of data from a retrospective cohort study involving patients who underwent primary TKA in Singapore. The patients\' baseline data, comorbidity, and surgical characteristics were collected. The independent variable was operation duration and the dependent variable was blood transfusion events. Patients were divided into three groups according to operation durations (90 and 120 min). Univariate logistic regression was used to explore the risk factors associated with blood transfusion after primary TKA. Multivariate analysis was used to assess the independent effect of operation duration on blood transfusion risk after adjusting for other covariates. Additionally, we performed subgroup analyses to identify specific groups, test the robustness of the relationships, and explore whether there were interactions between the different variables. Furthermore, restricted cubic splines (RCS) were used to identify the relationship between the two variables.
RESULTS: A total of 2,562 patients were included in the study, of whom 136 (5.61%) had a transfusion event. Operation durations were 95.55 ± 36.93 and 83.86 ± 26.29 min for blood transfused and non-transfused patients, respectively. Univariate logistic regression analysis showed that age, BMI, ASA status, Hb level, OSA, CHF, creatinine level > 2 mg/dL, and anaesthesia type were risk factors for blood transfusion. After adjusting for all covariates, multivariate logistic regression models showed that operation duration was positively associated with blood transfusion risk (odds ratio [OR] = 1.87, 95% CI = 1.174-2.933, P = 0.007). Compared to patients with an operation duration of less than 90 min, those with an operation duration of more than 120 min had a 2.141-fold increased risk of blood transfusion (OR = 2.141, 95% CI = 1.035-4.265, P = 0.035). Stratified analysis results showed that the association persisted in patients aged > 50 years, Chinese, BMI > 30 kg/m 2, Hb level > 11 g/dL, ASA status levels 2 and 3, general anaesthesia, and unilateral primary TKA. A non-linear (P-non-linear = 0.30) and J-shaped relationship was identified. The risk of transfusion increased as the operation duration decreased or exceeded the inflection point (73.2 min).
CONCLUSIONS: Our study demonstrated a non-linear and J-shaped relationship between operation duration and blood transfusion events in patients undergoing primary TKA. Blood transfusion risk was the lowest when the operation duration was 73.2 min. A shorter operation duration implies irregular surgical procedures and incomplete intraoperative haemostasis, leading to increased perioperative blood loss and blood transfusion. These results will be useful for clinical decision-making.
摘要：
目的：输血是初次全膝关节置换术（TKA）的常见围手术期并发症，可导致不良结局，住院时间延长,增加医疗费用。我们研究的目的是探讨输血的危险因素，并确定在调整其他协变量后，手术持续时间是否与接受原发性TKA的患者的输血风险独立相关。
方法：这是一项回顾性队列研究数据的次要分析，该研究涉及在新加坡接受原发性TKA的患者。患者的基线数据，合并症，并收集手术特点。自变量为手术时间，因变量为输血事件。根据手术时间（90和120分钟）将患者分为三组。采用单因素logistic回归分析原发性TKA术后输血的相关危险因素。在调整其他协变量后，采用多因素分析评估手术时间对输血风险的独立影响。此外,我们进行了亚组分析以确定特定的组，测试关系的稳健性，并探索不同变量之间是否存在相互作用。此外，受限三次样条(RCS)用于识别两个变量之间的关系。
结果：本研究共纳入2,562例患者，其中136人(5.61%)发生输血事件.输血和未输血患者的手术时间分别为95.55±36.93和83.86±26.29分钟，分别。单因素logistic回归分析显示,年龄,BMI,ASA状态，Hb水平,OSA,CHF,肌酐水平>2mg/dL，和麻醉类型是输血的危险因素。在调整所有协变量后，多因素logistic回归模型显示，手术时间与输血风险呈正相关（比值比[OR]=1.87，95%CI=1.174～2.933，P=0.007）。与手术时间少于90分钟的患者相比，手术时间超过120分钟的患者输血风险增加2.141倍(OR=2.141,95%CI=1.035~4.265,P=0.035).分层分析结果显示，年龄>50岁的患者之间存在关联，中文,BMI>30kg/m2，Hb水平>11g/dL，ASA状态2级和3级，全身麻醉，和单侧原发性TKA。确定了非线性(P-非线性=0.30)和J形关系。输血风险随着手术时间的减少或超过拐点（73.2min）而增加。
结论：我们的研究表明，接受原发性TKA的患者手术时间与输血事件之间存在非线性和J形关系。手术时间为73.2min时输血风险最低。较短的手术时间意味着不规则的外科手术和不完全的术中止血，导致围手术期失血和输血增加。这些结果将有助于临床决策。
方法：这是一项回顾性队列研究数据的次要分析，该研究涉及在新加坡接受原发性TKA的患者。患者的基线数据，合并症，并收集手术特点。自变量为手术时间，因变量为输血事件。根据手术时间（90和120分钟）将患者分为三组。采用单因素logistic回归分析原发性TKA术后输血的相关危险因素。在调整其他协变量后，采用多因素分析评估手术时间对输血风险的独立影响。此外,我们进行了亚组分析以确定特定的组，测试关系的稳健性，并探索不同变量之间是否存在相互作用。此外，受限三次样条(RCS)用于识别两个变量之间的关系。
结果：本研究共纳入2,562例患者，其中136人(5.61%)发生输血事件.输血和未输血患者的手术时间分别为95.55±36.93和83.86±26.29分钟，分别。单因素logistic回归分析显示,年龄,BMI,ASA状态，Hb水平,OSA,CHF,肌酐水平>2mg/dL，和麻醉类型是输血的危险因素。在调整所有协变量后，多因素logistic回归模型显示，手术时间与输血风险呈正相关（比值比[OR]=1.87，95%CI=1.174～2.933，P=0.007）。与手术时间少于90分钟的患者相比，手术时间超过120分钟的患者输血风险增加2.141倍(OR=2.141,95%CI=1.035~4.265,P=0.035).分层分析结果显示，年龄>50岁的患者之间存在关联，中文,BMI>30kg/m2，Hb水平>11g/dL，ASA状态2级和3级，全身麻醉，和单侧原发性TKA。确定了非线性(P-非线性=0.30)和J形关系。输血风险随着手术时间的减少或超过拐点（73.2min）而增加。
结论：我们的研究表明，接受原发性TKA的患者手术时间与输血事件之间存在非线性和J形关系。手术时间为73.2min时输血风险最低。较短的手术时间意味着不规则的外科手术和不完全的术中止血，导致围手术期失血和输血增加。这些结果将有助于临床决策。
