RESEARCH – January 2024

Survival and causes of death in tuberculosis patients in Estonia, 1997–2021

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Abstract

Background: Estonia is a region with high levels of tuberculosis, requiring the occurrence of tuberculosis to be monitored as a disease control measure.
Objective: To measure the survival of tuberculosis patients and compare their mortality with the general population, considering various factors such as education, ethnicity, and multidrug resistance.
Methods: The study used tuberculosis register and cause-of-death register data, as well as Statistics Estonia data (survival probabilities by sex, year, and age). Based on tuberculosis register data, a cohort was formed of adults (aged ≥ 15 years) who were diagnosed while alive with primary respiratory tuberculosis from 1997 to 2021. Survival in a cohort was measured using 5-year relative survival ratio (RSR) and 5-year standardised relative survival ratio (ARSR). Relative risk of death was measured using standardised mortality ratio (SMR). Mortality due to different factors was assessed by Poisson models and expressed with crude and adjusted (ARR) relative risk. All measures were accompanied with 95% confidence intervals.
Results: During the observation period, 5574 primary cases of respiratory tuberculosis were diagnosed in men and 2331 in women. The 5-year ARSR for men was 69.0% and for women 80.5%. In the age groups 15–44 and ≥ 75, the RSR for men was 83.9% and 68.0%, respectively, and for women 92.0% and 75.0%. The death risk for men was 3.49 and for women 2.95 times higher compared to the general population. The death risk was relatively high for respiratory diseases, alcohol-related causes, and external causes of death. In the cohort, the overall death risk was higher among non-Estonians (men ARR was 1.43, and women ARR 1.58) and among less educated individuals (men ARR was 1.41, and women ARR 1.44).

Summary: The RSR should be added to the indicators of tuberculosis control success. In further studies, factors could be examined that contribute to the higher overall mortality and cause-specific mortality among indiv iduals with tuberculosis compared to the general population.