Pai Madhukar, Joshi Rajnish, Dogra Sandeep, Mendiratta Deepak K, Narang Pratibha, Kalantri Shriprakash, Reingold Arthur L, Colford John M, Riley Lee W, Menzies Dick
Division of Epidemiology, School of Public Health, University of California, Berkeley, CA, USA.
Am J Respir Crit Care Med. 2006 Aug 1;174(3):349-55. doi: 10.1164/rccm.200604-472OC. Epub 2006 May 11.
Although interferon-gamma (IFN-gamma) assays are promising alternatives to the tuberculin skin test (TST), their serial testing performance is unknown.
To compare TST and IFN-gamma conversions and reversions in healthcare workers.
We prospectively followed-up 216 medical and nursing students in India who underwent baseline and repeat testing (after 18 mo) with TST and QuantiFERON-TB Gold In-Tube (QFT). TST conversions were defined as reactions greater than or equal to 10 mm, with increments of 6 or 10 mm over baseline. QFT conversions were defined as baseline IFN-gamma less than 0.35 and follow-up IFN-gamma greater than or equal to 0.35 or 0.70 IU/ml. QFT reversions were defined as baseline IFN-gamma greater than or equal to 0.35 and follow-up IFN-gamma less than 0.35 IU/ml.
Of the 216 participants, 48 (22%) were TST-positive, and 38 (18%) were QFT-positive at baseline. Among 147 participants with concordant baseline negative results, TST conversions occurred in 14 (9.5%; 95% confidence interval [CI] = 5.3-15.5) using the 6 mm increment definition, and 6 (4.1%; 95% CI = 1.5-8.7) using the 10 mm increment definition. QFT conversions occurred in 17/147 participants (11.6%; 95% CI = 6.9-17.9) using the definition of IFN-gamma greater than or equal to 0.35 IU/ml, and 11/147 participants (7.5%; 95% CI = 3.8-13.0) using IFN-gamma greater than or equal to 0.70 IU/ml. Agreement between TST (10 mm increment) and QFT conversions (>or= 0.70 IU/ml) was 96% (kappa = 0.70). QFT reversions occurred in 2/28 participants (7%) with baseline concordant positive results, as compared with 7/10 participants (70%) with baseline discordant results (p < 0.001).
IFN-gamma assay shows promise for serial testing, but repeat results need to be interpreted carefully. To meaningfully interpret serial results, the optimal thresholds to distinguish new infections from nonspecific variations must be determined.
尽管干扰素-γ（IFN-γ）检测有望成为结核菌素皮肤试验（TST）的替代方法，但其连续检测性能尚不清楚。
比较医护人员中TST和IFN-γ的转换及逆转情况。
我们对印度的216名医学生和护理学生进行了前瞻性随访，他们接受了TST和结核感染T细胞检测（QFT）的基线检测和重复检测（18个月后）。TST转换定义为反应大于或等于10mm，较基线增加6或10mm。QFT转换定义为基线IFN-γ小于0.35，随访IFN-γ大于或等于0.35或0.70IU/ml。QFT逆转定义为基线IFN-γ大于或等于0.35，随访IFN-γ小于0.35IU/ml。
216名参与者中，48名（22%）基线时TST呈阳性，38名（18%）基线时QFT呈阳性。在147名基线结果一致为阴性的参与者中，采用6mm增量定义时，14名（9.5%；95%置信区间[CI]=5.3-15.5）出现TST转换，采用10mm增量定义时，6名（4.1%；95%CI=1.5-8.7）出现TST转换。采用IFN-γ大于或等于0.35IU/ml的定义时，147名参与者中有17名（11.6%；95%CI=6.9-17.9）出现QFT转换，采用IFN-γ大于或等于0.70IU/ml的定义时，147名参与者中有11名（7.5%；95%CI=3.8-13.0）出现QFT转换。TST（10mm增量）与QFT转换（>或=0.70IU/ml）之间的一致性为96%（kappa=0.70）。28名基线结果一致为阳性的参与者中有2名（7%）出现QFT逆转，而10名基线结果不一致的参与者中有7名（70%）出现QFT逆转（p<0.001）。
IFN-γ检测显示出连续检测的前景，但重复结果需要谨慎解释。为了有意义地解释连续结果，必须确定区分新感染与非特异性变化的最佳阈值。
