VA Tennessee Valley Geriatric Research Education Clinical Center, Nashville, Tennessee, USA.
Clin Pharmacol Ther. 2011 Dec;90(6):813-9. doi: 10.1038/clpt.2011.228. Epub 2011 Nov 2.
Two important challenges are inherent in the design of studies using prescription data from electronic health records: how to define the minimum level of adherence that would qualify as "continuous drug use" and how to handle stockpiling of medications. Generally, the sensitivity of a study's conclusions to these design choices is not analyzed. In our study, covariate adjusted Cox models were used to compare persistence and durability with respect to three common oral antidiabetic therapies in a cohort of 12,697 incident users. Assuming 50% stockpiling, sulfonylurea therapy, as compared with metformin, showed a significantly lower risk of nonpersistence (changing or stopping therapy) when no gap days were allowed (HR 0.95, P = 0.032), no significant difference when 14 gap days were allowed (HR 0.99, P = 0.536), and significantly greater risk of nonpersistence when 30 gap days were allowed (HR 1.05, P = 0.046). All the drug comparisons showed statistically significant effects in both directions, the risk of nonpersistence increasing or decreasing depending on the design parameters.
如何定义符合“连续用药”标准的最低用药依从性水平，以及如何处理药物囤积问题。通常，研究结论对这些设计选择的敏感性并没有进行分析。在我们的研究中，针对 12697 例新诊断使用患者，使用协变量调整的 Cox 模型比较了三种常见口服抗糖尿病药物的持续用药和耐用性。假设存在 50%的药物囤积情况，与二甲双胍相比，在不允许有空白天数的情况下，磺酰脲类药物治疗的无持续用药（改变或停止治疗）风险显著降低（HR 0.95，P = 0.032）；允许有 14 个空白天数时，无显著差异（HR 0.99，P = 0.536）；允许有 30 个空白天数时，无持续用药风险显著增加（HR 1.05，P = 0.046）。所有药物比较在两个方向上均显示出统计学上的显著影响，无持续用药的风险取决于设计参数而增加或降低。
