Supplementary Material for: Carpal Tunnel Surgery as Proxy for Dialysis-Related Amyloidosis: Results from the Japanese Society for Dialysis Therapy

<b><i>Background/Aims:</i></b> This study aims to identify current risk factors for developing dialysis-related amyloidosis using carpal tunnel syndrome (CTS) as proxy for general amyloidosis. <b><i>Methods:</i></b> The cohort consisted of 166,237 patients on dialysis (mean age 66.1 ± 12.4 years; mean dialysis vintage 7.2 ± 6.4 years) who could be followed for a year between 2010 and 2011. Of these, 2,157 (1.30%) needed first-time CTS surgery during the study period. Odds ratios (ORs) for CTS were calculated at a 95% confidence interval (95% CI) after adjusting for age, gender, primary kidney disease, history of smoking, history of hypertension vintage, dialysis modality, use of high-flux membrane, body mass index, serum albumin, Kt/V, normalized protein catabolic rate, C-reactive protein, pretreatment β₂-microglobulin (β₂MG), and β₂MG clearance. <b><i>Results:</i></b> Adjusted ORs of first-time CTS for vintages 10-15, 15-20, 20-25 (referent), 25-30, and &gt;30 years were, respectively, 0.18 (0.12-0.26), 0.43 (0.31-0.62), 1.00, 2.37 (1.64-3.40), and 3.87 (2.52-5.93). Adjusted ORs for ages 40-50, 50-60 (referent), 60-70, 70-80, and &gt;80 were 0.53 (0.30-0.94), 1.00, 1.89 (1.41-2.52), 1.52 (1.08-2.14), and 1.04 (0.60-1.80). Female gender, low serum albumin, and diabetic nephropathy were also associated with CTS. Pretreatment serum β₂MG and β₂MG clearance &lt;80% were not significant, although β₂MG clearance &gt;80% was negatively associated with CTS [OR 0.34 (0.13-0.90)]. <b><i>Conclusion:</i></b> ORs of first-time CTS almost doubled with every 5-year increase in dialysis vintage. ORs of CTS were highest for patients aged 60-70. Other factors associated with CTS were gender, serum albumin, and diabetic nephropathy. β₂MG clearance &gt;80% may decrease the incidence of CTS.

**背景与目的**：本研究旨在以腕管综合征（carpal tunnel syndrome, CTS）作为全身性淀粉样变的替代标志物，明确当前与透析相关淀粉样变相关的危险因素。
**研究方法**：本队列纳入2010至2011年间可完成1年随访的166237名透析患者，其平均年龄为66.1±12.4岁，平均透析龄为7.2±6.4年。其中2157名（1.30%）患者在研究期间首次接受CTS手术。本研究以95%置信区间（95% CI）计算CTS的比值比（OR），校正变量包括年龄、性别、原发性肾脏疾病、吸烟史、高血压史、透析龄、透析方式、高通量膜（high-flux membrane）使用情况、体质量指数、血清白蛋白、Kt/V、标准化蛋白分解率（normalized protein catabolic rate）、C反应蛋白（C-reactive protein）、预处理β₂-微球蛋白（β₂-microglobulin, β₂MG）以及β₂MG清除率。
**研究结果**：以透析龄20~25年为参照组，透析龄10~15年、15~20年、25~30年及＞30年组的首次CTS校正OR值分别为0.18（95%CI：0.12~0.26）、0.43（95%CI：0.31~0.62）、1.00、2.37（95%CI：1.64~3.40）与3.87（95%CI：2.52~5.93）。以年龄50~60岁为参照组，40~50岁、60~70岁、70~80岁及＞80岁组的校正OR值分别为0.53（95%CI：0.30~0.94）、1.00、1.89（95%CI：1.41~2.52）、1.52（95%CI：1.08~2.14）与1.04（95%CI：0.60~1.80）。女性性别、低血清白蛋白水平与糖尿病肾病同样与CTS发病相关。预处理血清β₂MG及β₂MG清除率＜80%与CTS无显著关联，而β₂MG清除率＞80%则与CTS呈负相关[OR=0.34，95%CI：0.13~0.90]。
**研究结论**：透析龄每增加5年，首次CTS的OR值几乎翻倍。CTS发病风险在60~70岁患者中最高。其余与CTS相关的因素包括性别、血清白蛋白水平及糖尿病肾病。β₂MG清除率＞80%可降低CTS的发病风险。