Background The Health Assessment Questionnaire-Disability Index (HAQ-DI) is used to assess functional status in rheumatoid arthritis (RA), but the change required for meaningful improvements remains unclear. A minimum clinically important difference (MCID) of 0.22 is frequently used in RA trials. The aim of this study was to determine a statistically defined critical difference for HAQ-DI (HAQ-DI-dcrit) and evaluate its association with therapeutic outcomes. Methods We retrospectively analyzed data from adult German patients with RA enrolled in a multicenter observational trial in which they received adalimumab therapy at the decision of the treating clinician during routine clinical care. The HAQ-DI-dcrit, defined as the minimum change that can be reliably discriminated from random long-term variations in patients on stable therapy, was determined by evaluating intra-individual variation in patient scores. Other outcomes of interest included Disease Activity Score-28 joints and patient-reported pain and fatigue. Results The HAQ-DI-dcrit was calculated as an improvement (decrease) from baseline of 0.68 in a discovery cohort (N = 1645) of RA patients on stable therapy and with moderate disease activity (mean DAS28 [standard deviation] of 4.4 [1.6]). In the full patient cohort (N = 2740), 22.1% of patients achieved a HAQ-DI-dcrit improvement at month 6. Compared with patients with a small improvement in HAQ-DI (decrease of ≥0.22 to < 0.68) or no improvement (< 0.22), patients achieving a HAQ-DI-dcrit at month 6 had better therapeutic outcomes at months 12 and 24, including stable functional improvements. Change in pain was the most important predictor of HAQ-DI improvement during the first 6 months of therapy. Conclusions A HAQ-DI-dcrit of 0.68 is a reliable measure of functional improvement. This measure may be useful in routine clinical care and clinical trials. Trial registration ClinicalTrials.gov NCT01076205. Registered on February 26, 2010 (retrospectively registered).

中文翻译：

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使用“关键差异”统计标准提高了类风湿性关节炎患者的健康评估问卷-残疾指数评分的预测效用。

背景 健康评估问卷-残疾指数 (HAQ-DI) 用于评估类风湿关节炎 (RA) 的功能状态，但有意义的改善所需的变化仍不清楚。RA 试验中经常使用 0.22 的最小临床重要差异 (MCID)。本研究的目的是确定 HAQ-DI (HAQ-DI-dcrit) 的统计学定义的关键差异，并评估其与治疗结果的关联。方法 我们回顾性分析了参加一项多中心观察性试验的德国成年 RA 患者的数据，在该试验中，他们在常规临床护理期间根据主治临床医生的决定接受阿达木单抗治疗。HAQ-DI-dcrit，定义为可以可靠地区分稳定治疗患者的随机长期变化的最小变化，通过评估患者评分的个体内差异来确定。其他感兴趣的结果包括疾病活动评分-28 关节和患者报告的疼痛和疲劳。结果 HAQ-DI-dcrit 计算为从基线 0.68 的改善（降低）在一个发现队列（N = 1645）的 RA 患者稳定治疗和中度疾病活动（平均 DAS28 [标准偏差] 为 4.4 [1.6 ]）。在整个患者队列 (N = 2740) 中，22.1% 的患者在第 6 个月时实现了 HAQ-DI-dcrit 改善。与 HAQ-DI 小幅改善（降低 ≥0.22 至 < 0.68）或没有改善的患者相比(< 0.22)，在第 6 个月达到 HAQ-DI-dcrit 的患者在第 12 个月和第 24 个月有更好的治疗结果，包括稳定的功能改善。在治疗的前 6 个月，疼痛的变化是 HAQ-DI 改善的最重要预测因素。结论 0.68 的 HAQ-DI-dcrit 是衡量功能改善的可靠指标。该措施在常规临床护理和临床试验中可能有用。试验注册 ClinicalTrials.gov NCT01076205。2010年2月26日注册（追溯注册）。