Division of Public Health, Infectious Diseases and Occupational Medicine, Mayo Clinic, Rochester, MN, USA
Evidence-based Practice Center, Mayo Clinic, Rochester, Minnesota, USA.
BMJ Evid Based Med. 2023 Apr;28(2):133-136. doi: 10.1136/bmjebm-2021-111858. Epub 2022 Mar 9.
The fragility index (FI) was proposed as a simplified way to communicate robustness of statistically significant results and their susceptibility to a change of a handful number of events. While this index is intuitive, it is not anchored by a cut-off or a guide for interpretation. We identified cardiovascular trials published in six high impact journals from 2007 to 2021 (500 or more participants and a dichotomous statistically significant primary outcome). We estimated area under curve (AUC) to determine FI value that best predicts whether the treatment effect was precise, defined as adequately powered for a plausible relative risk reduction (RRR) of 25% or 30% or having a CI that is sufficiently narrow to exclude a risk reduction that is too small (close to the null, <0.05). The median FI of 201 included cardiovascular trials was 13 (range 1-172). FI exceeded the number of patients lost to follow-up in 46/201 (22.89%) trials. FI values of 19 and 22 predicted that trials would be precise (powered for RRR of 30% and 25%; respectively, combined with CI that excluded risk reduction <0.05). AUC for meeting these precision criteria was 0.90 (0.86-0.94). In conclusion, FI values that range 19-22 may meet various definitions of precision and can be used as a rule of thumb to suggest that a treatment effect is likely precise and less susceptible to random error. The number of patients lost to follow-up should be presented alongside FI to better illustrate fragility.
脆性指数（FI）被提出作为一种简化的方法来沟通统计学显著结果的稳健性及其对少数事件变化的敏感性。虽然这个指数很直观，但它没有一个截止值或解释指南。我们确定了 2007 年至 2021 年发表在六个高影响力期刊上的心血管试验（参与者超过 500 人且有二分类统计学显著的主要结局）。我们估计曲线下面积（AUC）来确定 FI 值，该值可以最好地预测治疗效果是否精确，定义为对于合理的相对风险降低（RRR）25%或 30%具有足够的效力，或者置信区间（CI）足够窄以排除太小的风险降低（接近零，<0.05）。201 项包含心血管试验的 FI 中位数为 13（范围为 1-172）。FI 值超过了 46/201（22.89%）试验中失去随访的患者数量。FI 值为 19 和 22 预测试验将是精确的（对于 RRR 为 30%和 25%具有效力；分别结合排除风险降低<0.05 的 CI）。符合这些精度标准的 AUC 为 0.90（0.86-0.94）。总之，范围在 19-22 的 FI 值可能符合各种精度定义，可以作为一种经验法则，表明治疗效果可能是精确的，并且不易受到随机误差的影响。应与 FI 一起报告失去随访的患者数量，以更好地说明脆性。
