Mazur D J, Merz J F
Department of Veterans Affairs Medical Center, Oregon Health Sciences University, Portland 97201.
J Gen Intern Med. 1994 May;9(5):268-71. doi: 10.1007/BF02599654.
To assess whether the type of scale used (scaling effects) and the severity of outcome (outcome severity) influence patients' numerical interpretations of verbal probability expressions.
Cross-sectional survey of patients in a general medicine clinic.
A university-based Department of Veterans Affairs Medical Center.
210 patients seen consecutively in a general medicine clinic.
The patients were randomized to scale and health outcome (complications of surgery). Two scales (a long form and a short form) were used to expressly allow patients to choose probabilities less than 1%. The long form had a lower bound of "< 1 out of 1,000,000"; the short form had a lower bound of "< 1 out of 1,000." Two complications were used: "death from anesthesia" and "severe pneumonia." In the context of being told that their surgeon believed that the chance the complication would occur was "rare," patients were asked to give the numerical estimate of that chance. The values elicited on both scales were significantly different for the two outcomes, with the "rare" risk of death from anesthesia being characterized as less likely than the "rare" risk of severe pneumonia (F = 5.24, p = 0.023). Linear regression and three-factor analysis of variance showed significant differences in the probabilities elicited for scale, outcome, and age, with older patients generally responding with higher probabilities than did younger patients.
These findings suggest that the severity of the associated outcome and the scale used to elicit patients' numerical estimates of verbal probability expressions influence patients' quantitative interpretations of the verbal probability statement; and older patients respond with higher probabilities of negative outcomes than do younger patients. Future studies must continue to explore whether verbal probability expressions are adequate for communicating medical risk to patients or whether patients should be provided with numerical estimates of frequency.
评估所使用的量表类型（量表效应）和结果的严重程度（结果严重程度）是否会影响患者对口头概率表达的数值解读。
对综合内科门诊患者进行横断面调查。
一所大学附属的退伍军人事务医疗中心。
综合内科门诊连续就诊的210名患者。
患者被随机分配到量表和健康结果（手术并发症）组。使用了两种量表（长表和短表），明确允许患者选择小于1%的概率。长表的下限为“<1/1,000,000”；短表的下限为“<1/1,000”。使用了两种并发症：“麻醉死亡”和“重症肺炎”。在被告知其外科医生认为并发症发生的可能性为“罕见”的情况下，要求患者给出该可能性的数值估计。两种结果在两种量表上得出的值存在显著差异，“罕见”的麻醉死亡风险被认为比“罕见”的重症肺炎风险可能性更小（F = 5.24，p = 0.023）。线性回归和三因素方差分析显示，量表类型、结果和年龄所引发的概率存在显著差异，老年患者的反应概率通常高于年轻患者。
这些发现表明，相关结果的严重程度以及用于引发患者对口头概率表达进行数值估计的量表会影响患者对口头概率陈述的定量解读；并且老年患者对负面结果的反应概率高于年轻患者。未来的研究必须继续探索口头概率表达是否足以向患者传达医疗风险，或者是否应该为患者提供频率的数值估计。
