Research on the application of two skin test reagents in screening close contacts of pulmonary tuberculosis
Objective The screening efficacy and economic benefits of using recombinant mycobacterium tuberculosis fusion protein(EC)or purified protein derivative of tuberculin(PPD)as skin tests were evaluated in close contacts with pulmona-ry tuberculosis using interferon-gamma release assays(IGRA),providing a reference for subsequent school tuberculosis screening work.Methods The close contacts of tuberculosis patients at a given time was randomly divided into EC group and PPD groups.IGRA was applied as the standard to determine the screening results of EC and PPD.The second screening was completed 3 months later,and the test was repeated again for those with negative PPD,EC,and IGRA results.Calculate the sensitivity,specificity,accuracy index,Kappa value,predictive value,and area under the ROC curve of EC and PPD tests after the two screenings,and analyze their cost-effectiveness ratio.Statistical analyses was conducted using SPSS 25.0.Results A total of 491 close contacts with tuberculosis were screened,9 were shed,239 in the EC group and 243 in the PPD group.After two screening,the latent infection rate of EC group was 4.60%,the sensitivity was 66.67%,the specificity was 98.68%,the correct index was 97.07%,the positive predictive value was 72.72%,the negative predictive value was 98.25%,the Kappa value was 0.680,and the area under the ROC curve was 0.827.The latent infection rate of PPD group was 18.93%,the sensitivity was 69.23%,the specificity was 83.91%,the correct index was 83.13%,the positive predictive value was 19.57%,and the negative predictive value was 97.97%,the Kappa value was 0.242,and the area under the ROC curve was 0.766.The screening cost per hundred people in the EC group was lower than that in the PPD group.When eval-uating the cost-effectiveness ratio(effect was latent tuberculosis infection),it was higher in the EC group than that in the PPD group.When evaluating the effect using the number of people who were positive for both skin tests and IGRA,it was lower in the EC group than that in the PPD group.Based solely on the results of the skin test,11 patients(4.60%)in the EC group required preventive treatment,while 27 patients(11.11%)in the PPD group.Conclusion Compared to PPD,EC has higher specificity and better consistency with IGRA detection results in screening for latent infections in close con-tacts of pulmonary tuberculosis.At the same time,EC can reduce the number of people receiving preventive treatment due to false positive of PPD.Although it is still controversial in terms of economic benefits,it is still a better method of skin test and has some value for dissemination.
Recombinant mycobacterium tuberculosis fusion proteinPurified protein derivative of tuberculinLatent tuber-culosis infection