Background

Significant benefit of intravenous ferric carboxymaltose (FCM) treatment for restless legs syndrome (RLS) has been well-established. However, no clinical indicators predicting treatment response of RLS have been established. This study aimed to determine factors predicting outcome of clinical FCM treatment of RLS patients.

Methods

Data were retrospectively reviewed from all patients who received FCM treatment for RLS from April 2016 to April 2019. These data included: detailed history, international RLS scale score (IRLS), questionnaires, comorbidity, and previous RLS medication use. Morning fasting serum iron, ferritin, and total iron-binding capacity were measured before and at four weeks after treatment. RLS patients with possible secondary RLS were identified by reviewing the medical histories. This included patients with iron deficiency anemia, lumbosacral radiculopathy, and gastrectomy. Primary RLS included those with no indication of secondary medical factors contributing to RLS. Treatment response was assessed using the IRLS and clinical ratings at four weeks after FCM administration. Patients with a greater than 40% decrease in IRLS were classified as responders.

Results

The study comprised 164 patients with IRLS and clinical ratings obtained before and at four weeks after intravenous (IV) iron. Treatment responses differed considerably between diagnostic groups of RLS. Percentage responding was: 64.7% (66 of 102) for patients with primary RLS, 90.9% (10 of 11) with gastrectomy, 91.3% (21 of 23) with iron deficiency anemia and 39.3% (11 of 28) with lumbosacral radiculopathy. When responders were compared to non-responders in primary RLS patients, responders had significantly lower serum iron (80.5 ± 26.7 vs. 95.8 ± 30.5 μg/dL, p = 0.022) and percentage transferrin saturation (%TSAT) (25.4 ± 9.6 vs. 30.5 ± 10.5%, p = 0.026) in females, but not males. Logistic regression controlling for major subject variables showed that %TSAT significantly predicted response. (odds ratio [OR]: 0.955, confidence interval: 0.913–0.998, p = 0.040).

Conclusion

Intravenous FCM in moderate to severe RLS patients is beneficial as a first-line or add-on treatment, particularly for patients with compromised peripheral iron state. Overall, lower %TSAT predicted better chance of responding to the IV iron treatment especially for females.

中文翻译：

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患者特征预示了对躁动性腿综合征静脉内注射羧甲基麦芽糖铁的反应。

背景

静脉内羧化麦芽糖铁（FCM）治疗不安腿综合征（RLS）的显着益处已得到公认。但是，尚未建立预测RLS治疗反应的临床指标。这项研究旨在确定预测RLS患者临床FCM治疗结果的因素。

方法

回顾性分析了2016年4月至2019年4月接受FCM治疗RLS的所有患者的数据。这些数据包括：详细病史，国际RLS量表评分（IRLS），问卷，合并症和以前使用RLS药物。在治疗前和治疗后四周测量早晨的空腹血清铁，铁蛋白和总铁结合能力。通过回顾病史确定可能伴发继发性RLS的RLS患者。其中包括铁缺乏性贫血，腰ac神经根病和胃切除术的患者。初级RLS包括那些没有导致RLS的二级医学因素的迹象。使用FCM后四周，使用IRLS和临床评分评估治疗反应。IRLS降低幅度大于40％的患者被归类为反应者。

结果

该研究纳入了164名具有IRLS的患者，并在静脉注射铁（IV）之前和之后四周获得了临床评分。RLS诊断组之间的治疗反应差异很大。缓解百分比为：原发性RLS患者的64.7％（102名中的66名），胃切除术患者90.9％（11名中的10名），铁缺乏性贫血的91.3％（23名中的21名）和腰s神经根病的39.3％（28名中的11名）。当将原发性RLS患者的反应者与无反应者进行比较时，反应者的血清铁水平明显降低（80.5±26.7 vs. 95.8±30.5μg/ dL，p  = 0.022）和转铁蛋白饱和度百分比（％TSAT）（25.4±9.6vs。 30.5±10.5％，p = 0.026），但女性没有。对主要受试者变量进行的逻辑回归控制表明，％TSAT显着预测了反应。（赔率[OR]：0.955，置信区间：0.913-0.998，p  = 0.040）。

结论

中重度RLS患者的静脉FCM作为一线或附加治疗是有益的，特别是对于周围铁状态受损的患者。总体而言，较低的TSAT值预示着对IV铁治疗有较好反应的机会，特别是对于女性。