Abstract:

Objective: To analyze the screening situation of close contacts and time changing trends of pulmonary tuberculosis (PTB) patients in Chongqing from 2015 to 2024, and to provide a basis for improving the efficiency of PTB detection and the standardized management of close contacts. Methods: Data on all registered active PTB patients and etiologically-positive PTB patients in Chongqing from January 1, 2015, to December 31, 2024, as well as data from three times of follow-up screening of close contacts (at initial diagnosis, 6 months, and 1 year), were collected from the China Information System for Disease Control and Prevention. Joinpoint regression was used to analyze the temporal trends of average number of close contacts registered per index case, tuberculosis examination rate, detection rate of active PTB among close contacts, and contribution rate of close contact screening to PTB patient discovery, using Annual Average Percent Change (AAPC) and Annual Percent Change (APC). Results: From 2015 to 2024, a total of 161163 cases of PTB cases, 81280 PTB index cases and 210311 close contacts were registered in Chongqing. Among them, household contacts accounted for 69.72% (146624/210311), and non-household contacts accounted for 30.28% (63687/210311), with an average of 2.59 close contacts registered per index case. A total of 206067 close contacts were screened for suspicious PTB symptoms, with a screening rate of 97.98%; however, only 6.44% (13265/206067) were found to have suspicious symptoms. A total of 152991 close contacts underwent tuberculosis examinations, representing an examination rate of 72.75%. In total, 1501 active PTB patients were detected, yielding a detection rate of 0.98% (1501/152991). The contribution rate of close contact screening to overall PTB patient discovery was 0.93% (1501/161163). Joinpoint trend analysis indicated that the average number of registered close contacts per index case showed an upward trend from 2015 to 2024 (AAPC=12.287%, 95%CI: 7.800% to 15.508%, P<0.001), with a significant increase observed from 2021 to 2024 (APC=41.482%, 95%CI: 21.084% to 76.752%, P<0.001). Conversely, both the tuberculosis examination rate and the detection rate of active PTB among close contacts showed downward trends (AAPC=-6.631%, 95%CI: -10.722% to-2.017%, P=0.004; AAPC=-27.791%, 95%CI:-46.442% to -2.882%, P=0.032), with the examination rate declining significantly from 2021 to 2024 (APC=-18.192%, 95%CI:-36.210% to -7.334%, P=0.002). Conclusion: From 2015 to 2024, the average number of close contacts registered for each index case in Chongqing showed an upward trend, while the tuberculosis screening rate and the detection rate of PTB patients among close contacts decreased. The contribution of close contacts screening to case detection was relatively low. It is recommended to further standardize the close contacts screening work, increase the tuberculosis screening rate, so as to enhance the detection rate of PTB patients and the contribution of close contacts screening to case detection.

Key words: Tuberculosis, pulmonary, Contact tracing, Mycobacterium infections, Population surveillance, Communicable disease control