Spatiotemporal trends in tuberculosis incidence in Thailand, 2012-2023: a nationwide, province-level analysis

Tuberculosis (TB) remains a major public health challenge in Thailand, a high-burden country undergoing both epidemiological transition and pandemic-related disruption. This study examined temporal and spatial patterns of age-standardized TB incidence from 2012 to 2023 across Thailand's 13 health regions and 77 provinces.

This nationwide ecological study used annual TB case notifications (2012-2023) for all 77 Thai provinces from Thailand's National Disease Surveillance System (Report 506), Bureau of Epidemiology, with mid-year and age-stratified provincial populations. Age-standardized incidence rates (ASR) were calculated using the WHO World Standard Population (2000-2025). Temporal trends were assessed by Joinpoint regression with Bayesian-Information-Criterion model selection (maximum 2 joinpoints) and validated by generalized additive models. Spatial clustering was evaluated by Global Moran's I and Local Indicators of Spatial Association (LISA) under queen contiguity, with sensitivity analyses across alternative weights and Benjamini-Hochberg false-discovery-rate correction. Provinces were classified into long-term trend categories combining effect size (AAPC) and significance, and COVID-19 impact was quantified by 2019-2023 ASR percent change.

National TB incidence declined substantially from 2012 to 2023, although marked regional heterogeneity persisted. Five health regions showed the strongest long-term reductions: region 3 [AAPC: - 20.51, 95% confidence interval (CI): - 33.00 to - 13.77], region 9 (- 19.42, 95% CI: - 28.98 to - 8.57), region 4 (- 17.53, 95% CI: - 23.64 to - 12.89), region 11 (- 11.79, 95% CI: - 22.16 to - 0.04), and region 13 (- 11.19, 95% CI: - 22.44 to - 3.74). Region 6 showed an early decline followed by stabilisation, and region 12 showed a mid-period increase before a post-2019 reduction.

Thailand has achieved substantial overall reductions in TB incidence over the past decade, but pronounced regional and provincial disparities persist. Localized hot-spots, biphasic regional trajectories that may reflect surveillance and programmatic transitions, and compound vulnerability during the COVID-19 period underscore the need for geographically targeted monitoring, equitable resource allocation, and pro-poor interventions to sustain progress toward TB elimination.