巢式病例对照研究在中医药治疗糖尿病肾病疗效评价中的应用探讨

目的：采用巢式病例对照研究评价中医药治疗糖尿病肾病的疗效并探讨该设计在中医药疗效评价中应用的可行性。方法：采用巢式病例对照研究设计，以队列研究纳入的糖尿病肾病患者为研究的源人群，按病例组与对照组1：4的比例选取研究对象，要求病例组与对照组在年龄、性别、民族等方面相匹配。采用EpiData3．1软件录入数据，应用SAS软件采用条件logistic回归的方法分析治疗方案（中西医结合与单纯西医治疗）与糖尿病肾病疾病进展的关系；对巢式病例对照研究的把握度进行估计，根据现有资料对巢式病例对照研究和队列研究的样本含量进行再估计。结果：共纳入发生终点结局事件的病例8例作为病例组，匹配未发生结局事件的对照病例32例作为对照组，病例组与对照组在文化程度、停药、治疗方案改变和辨证论治等方面比较差异无统计学意义，病例组与对照组接受的治疗方案分布差异无统计学意义（比值比=0．725，95％置信区间为0．174-3．030）。根据该结果反推计算的把握度为5％。如需达到80％的把握度，1：4病例对照研究样本含量为1350（270：1080），1：1为880（440：440），1：1队列研究样本含量为1020（510：510）。结论：本研究未发现中西医结合治疗方案、西医治疗方案与糖尿病肾病疾病进展的关系。巢式病例对照研究可以应用于中医药疗效评价，但是应开展中医药疗效的前期基础研究如横断面研究，以期为病例对照研究、队列研究和随机对照试验的验证研究提供样本量估算的依据。

Using nested case-control study to appraise the effectiveness of Chinese medicines in the treatment of diabetic nephropathy

OBJECTIVE： A nested case-control study was carried out to assess the effectiveness of Chinese medicines in the treatment of diabetic nephropathy, so as to explore the feasibility of using nested case-control study on effect assessment of Chinese medicine. METHODS： Nested case-control study was applied and the participants were enrolled from the subjects recruited in a cohort study. The cases and the controls were matched by 1 to 4 in age, gender, nationality and the stage of diabetic nephropathy when recruited in the cohort study. The EpiData 3.1 software was used for inputting data and SAS system was used for data analysis. Conditional logistic regress was applied to analyze the relationship between treatment and the progression of diabetic nephropathy. The study power was estimated and the sample sizes for case-control study and cohort study were recalculated based on the data from the cohort study. RESULTS： Eight cases and 32 controls were recruited in this study. The education level, ratio of drug withdrawal, change of therapy, syndromedifferentiation and treatment were not significantly different in case and control groups. The progression of diabetic nephropathy was not significantly related with the treatment and the odds ratio （OR） value was 0. 725 with a 95% confidence interval from O. 174 to 3. 030. The statistical power of the study was 5%. To achieve the statistical power of 80%, 1 350 （270 ~ 1 080） participants were needed for 1 ： 4 matched case-control study, 880 （440 ： 440） for 1 ~ 1 paired case-control study, and 1 020 （510 ~ 510） for 1 ~ I control study. CONCLUSION： The treatment method is not significantly related with the progress of diabetic nephropathy. The nested case-control study is applicable in the therapeutic effect evaluation of Chinese medicine. Basic studies such as cross-sectional studies should be carried out to supply fundamental information for other types of studies including case-control study, cohort study and randomized clinical trials. Large sample size studies were needed to appraise the effect of Chinese medicine.