单项和联合指标在结节病诊断中的预测价值评价

Predictive value of single and combined indexes in the diagnosis of sarcoidosis

目的评价结节病诊断中各单项和联合诊断指标的预测价值。方法回顾性分析北京协和医院2001年1月至2007年9月间88例初步诊断为结节病的患者的临床资料，应用受试者工作特征曲线（ROC曲线）和Bayes方法对BALF细胞分类中的淋巴细胞比例、淋巴细胞亚群CD4／CD8、血清血管紧张素转换酶（ACE）等3项指标及其联合指标的诊断预测价值进行评价。采用ROC曲线评价各指标的诊断价值并确定指标的界定值，采用判别分析和ROC曲线评价联合指标的诊断价值。结果在88例初步诊断为结节病的患者中，经活检确诊结节病59例（67％），男性16例（27％），女性43例（73％），平均年龄（48±10）岁；排除结节病29例（33％），男性12例（41％），女性17例（59％），平均年龄（49±13）岁。单项指标淋巴细胞比例、CD4／CD8值和ACE的ROC曲线下面积分别为0．64、0．74和0．69，CD4／CD8值在3项指标中的诊断效率最高；通过ROC曲线的切点和坐标结合确定3项指标的最佳界定值是淋巴细胞比例≥30％，CD4／CD8值≥4．0，ACE≥40U／L；其阳性预测值分别为76．7％、80．4％和76．8％，表明CD4／CD8值在3项指标中的预测价值最高。CD4／CD8值和ACE联合指标的曲线下面积为0．81，CD4／CD8值、ACE、淋巴细胞比例3项联合指标的曲线下面积为0．78，均大于单项指标的曲线下面积，前者的诊断效率优于后者。CD4／CD8值和ACE并联指标的阳性预测值为83．9％，串联指标的阳性预测值为90．5％，明显高于单项指标的相同评价指标，表明将CD4／CD8值和ACE联合起来诊断结节病的效率和预测价值均高于各单项指标。结论BALF淋巴细胞亚群中CD4／CD8值仍然是辅助诊断结节病的有效单项指标，采用CD4／CD8值和ACE联合指标诊断结节病可提高诊断效率和预测价值。

Objective To evaluate the predictive value of single and combined indexes in the diagnosis of sarcoidosis. Methods Eighty-eight patients suspected of having sarcoidosis were retrospectively investigated. The diagnostic predictive value of lymphocyte percentage and CD4/CD8 ratio in bronchoalveolar lavage （BAL） , angiotensin converting enzyme （ACE） and their combination was evaluated by ROC curve method and Bayes＇ rule. Results Final diagnosis of sarcoidosis by biopsy was available in 59 patients （67%）, 16 were males （27%）, 43 were females （73%）, with a mean age of （48 ±10） years. The diagnosis of non-sarcoidosis was available in 29 patients （33%） , 12 were males （41%） , 17 were females （59%） , with a mean age of （49 ± 13） years. The ROC curve area of lymphocyte percentage, CD4/CD8 ratio and ACE were 0. 64, 0. 74 and 0. 69 respectively; CD4/CD8 ratio had the best diagnostic efficiency. The optimized cut-offs of the three single indexes, lymphocyte percentage ≥30% , CD4/CD8 ratio ≥4. 0 and ACE≥40 U/L, were determined by the tangential points and coordinates of the ROC curve. The positive predictive values were 76. 7% , 80.4% and 76. 8% respectively; CD4/CD8 ratio had the best predictive value. The ROC curve area of the combined CD4/CD8 ratio and ACE was 0. 81, and the combination of lymphocyte percentage, CD4/CD8 ratio and ACE was 0. 78. They were both higher than those of the respective single indexes. The combination of CD4/CD8 ratio and ACE had the best diagnostic efficiency. On the other hand, it had the best positive predictive value of 90. 5% in all the diagnostic indexes. Conclusion CD4/CD8 ratio in BAL is still a useful index in the auxiliary diagnosis of sarcoidosis. The combination of CD4/CD8 ratio and ACE can improve the diagnostic efficiency and predictive value of sarcoidosis.