Departments of Urology and Public Health, University of Helsinki and Helsinki University Hospital, Haartmaninkatu 4, 00029 Helsinki, Finland.
Department of Health Research Methods, Evidence, and Impact, McMaster University, 1280 Main St West, Hamilton, ON L8S 4L8, Canada.
J Clin Epidemiol. 2018 Dec;104:46-51. doi: 10.1016/j.jclinepi.2018.08.014. Epub 2018 Aug 23.
The Grading of Recommendations Assessment, Development and Evaluation approach to rating certainty of evidence includes five domains of reasons for rating down certainty. Only one of these, precision, is easily amenable-through the confidence interval-to quantitation. The other four (risk of bias, inconsistency, indirectness, and publication bias) are not. Nevertheless, conceptually, one could consider a quantified "certainty range" within which the true effect lies. The certainty range would be at least as wide as the confidence interval and would expand with each additional reason for uncertainty.
We have applied this concept to rating the certainty of evidence in the baseline risk of venous thromboembolism (VTE) and bleeding in patients undergoing urological surgery. We considered rating up moderate or low quality evidence when the net benefit of VTE prophylaxis was unequivocally positive, that is, when the smallest plausible value of VTE reduction was greater than the largest plausible value of increased bleeding. To establish whether the net benefit was unequivocally positive, we expanded the range of plausible values by 20% for each of the four nonquantitative domains in which there were serious limitations.
We present how we applied these methods to examples of open radical cystectomy and laparoscopic partial nephrectomy. In high-VTE risk laparoscopic partial nephrectomy patients and high- and medium-VTE risk open radical cystectomy patients, results proved robust to expanded certainty intervals, justifying rating up quality of evidence. In low-risk patients, the results were not robust, and rating up was therefore not appropriate.
This work represents the first empirical application in a decision-making context of the previously suggested concept of certainty ranges and should stimulate further exploration of the associated theoretical and practical issues.
推荐评估、制定和评估方法（Grading of Recommendations Assessment, Development and Evaluation approach）对证据确定性的评级包括五个降低确定性的原因领域。其中只有一个（精确度）可以通过置信区间很容易地进行量化。其他四个（偏倚风险、不一致性、间接性和发表偏倚）则不行。然而，从概念上讲，人们可以考虑一个量化的“确定性范围”，真实效应就在这个范围内。这个确定性范围至少应该与置信区间一样宽，并随着不确定性的每一个额外原因而扩大。
我们将这一概念应用于评估接受泌尿外科手术的患者的基线静脉血栓栓塞（venous thromboembolism，VTE）和出血风险的证据确定性。当 VTE 预防的净效益是明确的阳性时，我们考虑对中等或低质量的证据进行评级上调，也就是说，当 VTE 减少的最小可能值大于增加出血的最大可能值时。为了确定净效益是否是明确的阳性，我们在存在严重局限性的四个非定量领域中的每一个领域都将可能值的范围扩大了 20%。
我们展示了如何将这些方法应用于开放根治性膀胱切除术和腹腔镜部分肾切除术的例子。在高 VTE 风险的腹腔镜部分肾切除术患者和高、中 VTE 风险的开放根治性膀胱切除术患者中，结果对扩大的确定性区间具有稳健性，证明了对证据质量进行评级上调是合理的。在低风险患者中，结果不稳健，因此不适合进行评级上调。
这项工作代表了在决策背景下首次对先前提出的确定性范围概念进行实证应用，应该会激发对相关理论和实际问题的进一步探索。
