Abstract:

Objective: To analyze the etiological positive rate among pulmonary tuberculosis (PTB) patients in Ordos City, Inner Mongolia Autonomous Region from 2015 to 2024, and to evaluate the application value of molecular diagnostic techniques in the early diagnosis of PTB. Methods: Data from 4394 PTB patients with laboratory testing results, reported by nine designated TB hospitals in Ordos City between 2015 and 2024, were extracted from the “Tuberculosis Information Management System” of Chinese Center for Disease Control and Prevention. The usage rates and positive rates of three diagnostic methods were assessed: acid-fast bacilli (AFB) smear microscopy, Mycobacterial culture, and molecular diagnostic assay. Results: From 2015 to 2017, AFB smear microscopy was the primary diagnostic method. Molecular diagnostic assays were gradually introduced begining in 2018. The utilization rate of smear microscopy remained 93.95%-100.00% in most years, except in 2018 (84.12%, 445/529). In contrast, the utilization rates of culture and molecular methods increased from 1.70% (9/529) and 25.90% (137/529) in 2018 to 76.72% (356/464) and 92.24% (428/464) in 2024, respectively, showing significant annual upward trend ( {\chi }_{trend}^2=1885.69, P<0.001; {\chi }_{trend}^2=2150.208, P<0.001).The overall etiological positive rate for PTB in Ordos significantly increased from 28.44% (128/450) in 2015 to 75.44% (344/456) in 2024 ( {\chi }_{trend}^2=682.623, P<0.001). Between 2018 and 2024, the overall positive rate of molecular methods (74.38% (1405/1889)) was significantly higher than that of culture (54.85% (921/1679)) and smear microscopy (33.40% (1425/4267)), with significant difference (χ²=922.943, P<0.001). Among all etiologically positive results, the proportion of positive cases only by smear microscopy decreased from 98.44% (126/128) in 2015 to 2.91% (10/344) in 2024, while the proportion detected only by culture consistently remained between 0.45% (1/221) and 5.71% (16/280). Conversely, the proportion of cases positive with molecular biological methods increased from 0.00% before 2018 to 90.41% (311/344) in 2024, with the most significant increase in cases detected only by molecular methods (rising from 17.55% (43/245) in 2019 to 36.34%(125/344) in 2024) and by all three methods combined (rising from 10.20% (25/245) in 2019 to 27.62% (95/344) in 2024). For smear-negative patients, the molecular detection positive rates at citywide, municipal-level, and county-level designated hospitals increased from 0.33% (1/303), 0.54% (1/185), and 0.00% (0/118) in 2018 to 60.00% (165/275), 53.37% (95/178), and 72.16% (70/97) in 2024, respectively, all showing significant annual upward trends ( {\chi }_{trend}^2=867.785, P<0.001; {\chi }_{trend}^2=421.652, P<0.001; {\chi }_{trend}^2=445.559, P<0.001). Notably, the positive rate at banner (district)-level hospitals surpassed that at municipal-level hospitals in 2024, with statistically significant difference ( {\chi }_{trend}^2=9.240, P=0.002). Conclusion: From 2015 to 2024, both the etiological positive rate of pulmonary tuberculosis and the positive rate among smear-negative patients in Ordos City showed continuous annual increases. Although the utilization rate of smear microscopy remained high, its dominant role in positive diagnosis has gradually diminished. While the utilization rates of both culture and molecular testing increased annually, the positive detection rate of culture has consistently been low, resulting in limited clinical impact. Consequently, molecular testing has become the primary diagnostic method. It is recommended to adopt molecular testing for etiological confirmation. Furthermore, attention should be paid to improving the positive detection rate among smear-negative patients in municipal-level designated hospitals.

Key words: Mycobacterium tuberculosis, Diagnostic techniques and procedures, Molecular diagnostic techniques, Data interpretation, statistical, Small-area analysis, Ordos