T-Spot.TB与PPD预测家庭密切接触者是否患活动性结核的价值研究

Study on predicting active tuberculosis among household contacts with T-Spot. TB and PPD

目的探讨T-Spot.TB和PPD在预测家庭密切接触者是否患活动性结核的作用和价值。方法 2011年1月至2013年12月,1 274名无症状的密切接触涂阳肺结核患者的家庭成员,同时做TSpot.TB和PPD,然后随访4年看是否患结核。结果 T-Spot.TB与以15 mm为界值的PPD相比阳性率更高(32.6%/22.1%),且与暴露时间相关性更好。不管接触者是否有卡介苗接种瘢痕,T-Spot.TB和以5 mm、10 mm、15 mm为界值的PPD,两者一致性相对较差。T-Spot.TB(IRR8.6)和PPD(界值为5 mm、10 mm、15 mm的IRR值分别为3.8、6.1、2.9)均能帮助预测TB。以15 mm为界值的PPD,会漏掉54.8%的活动性结核病例和63.2%的微生物学确诊的病例。如果降低界值为5 mm或10 mm,能提高敏感性,但是却降低了特异性,这样就会导致更多的假阳性病例。结论在卡介苗覆盖率很高的中国,T-Spot.TB比PPD在预测家庭密切接触者是否患结核方面,价值更高。

Objective In China,the coverage of neonatal BCG vaccination is up to 98.7%.This study was to analyze the value of T-Spot.TB and PPD in predicting active TB among household contacts.Methods From January 2011 to 31 December 2013,1274 asymptomatic household contacts of smear-positive patients were simultaneously tested with T-Spot.TB and PPD,and then followed for up to 4 years to investigate the development of active tuberculosis.Results T-Spot.TB had a significantly higher positive rate than PPD at the 15mm cut-off.Agreement between T-Spot.TB and PPD using cut-offs of 5,10 and 15 mm were relatively poor irrespective of presence or absence of BCG scar.Both T-Spot.TB(IRR8.6)and PPD(IRR:3.8,6.1 and 2.9,using cut-offs of 5 mm,10 mm and 15 mm,respectively)could predict TB.Different PPD cut-offs had different sensitivities and specificities.Lower cut-off could achieve sensitivity,but at the expense of lower specificity.Conclusions T-Spot.TB outperformed PPD in predicting TB among household contacts in an area with widespread BCG vaccination coverage.