Anemia, sarcopenia, physical activity, and the risk of tuberculosis in the older population: a nationwide cohort study

Background: The aim of this study was to investigate whether physical activity, sarcopenia, and anemia are associated an with increased risk of tuberculosis (TB) among the older population. Methods: We included 1,245,640 66-year-old subjects who participated in the National Screening Program for Transitional Ages for Koreans from 2009 to 2014. At baseline, we assessed common health problems in the older population, including anemia and sarcopenia. The subjects' performance in the timed up-and-go (TUG) test was used to predict sarcopenia. The incidence of TB was determined using claims data from the National Health Insurance Service database. Results: The median follow-up duration was 6.4 years. There was a significant association between the severity of anemia and TB incidence, with an adjusted hazard ratio (aHR) of 1.28 [95% confidence interval (CI), 1.20-1.36] for mild anemia and 1.69 (95% CI, 1.51-1.88) for moderate to severe anemia. Compared with those who had normal TUG times, participants with slow TUG times (> 15 s) had a significantly increased risk of TB (aHR 1.19, 95% CI, 1.07-1.33). On the other hand, both irregular (aHR 0.88, 95% CI 0.83-0.93) and regular (aHR 0.84, 95% CI, 0.78-0.92) physical activity reduced the risk of TB. Male sex, lower income, alcohol consumption, smoking, diabetes, and asthma/chronic obstructive pulmonary disease increased the risk of TB. Conclusion: The risk of TB among older adults increased with worsening anemia, sarcopenia, and physical inactivity. Physicians should be aware of those modifiable predictors for TB among the older population.