Joint associations of multiple lifestyle factors with risk of active TB in the population

Who

• 63,257 Chinese adults (men and women), aged 45–74 years at recruitment

• Belonged to Hokkien and Cantonese dialect groups

• Participants of the Singapore Chinese Health Study

• A subset of 39,528 participants contributed updated lifestyle data at follow-up

• Participants were born in the first half of the 20th century, many likely exposed to latent tuberculosis infection early in life

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What

• The study examined the joint association of five lifestyle risk factors—smoking, underweight BMI, physical inactivity, daily alcohol consumption, and poor diet quality—with the risk of active tuberculosis (TB).

• Each individual risk factor was independently associated with higher TB risk.

• A dose–response relationship was observed: increasing numbers of lifestyle risk factors were associated with stepwise increases in TB risk.

• Participants with all five risk factors had a ~9-fold higher risk of active TB compared with those with none.

• The combined effect of all five factors was greater than expected under a purely multiplicative model, suggesting synergistic effects.

• The association was stronger among participants with diabetes, indicating effect modification.

• Smoking showed synergistic interactions with alcohol drinking and poor diet quality.

• Findings support multifactorial prevention strategies targeting lifestyle behaviors to reduce TB risk.

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When

• Baseline recruitment: April 1993 – December 1998

• Second follow-up: 2006–2010 (mean 12.7 years after baseline)

• Mean follow-up duration: 18.2 years (SD 5.9)

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Where

• Singapore, among residents living in government housing flats (where ~86% of the population lived during recruitment)

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Why

• Tuberculosis incidence has declined slowly, and effective preventive strategies remain limited.

• Older adults in Singapore, many with latent TB infection acquired earlier in life, remain at risk of reactivation.

• The study aimed to clarify how modifiable lifestyle factors jointly influence active TB risk, addressing a gap in population-level prevention evidence.

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How

• Prospective population-based cohort study

• Lifestyle factors assessed via structured interviewer-administered questionnaires at baseline and follow-up

• Diet assessed using a validated 165-item food-frequency questionnaire

• A combined lifestyle risk score (0–5) was constructed, assigning one point per at-risk factor

• Incident active TB cases identified through mandatory linkage with the National TB Notification Registry

• Cox proportional hazards models used to estimate hazard ratios, with adjustment for confounders

• Sensitivity analyses and time-varying covariate analyses confirmed robustness of findings

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Overall conclusion:
An increasing number of unhealthy lifestyle factors is associated with a markedly higher risk of active tuberculosis in older Chinese adults, underscoring the importance of integrated, multisectoral lifestyle interventions for TB prevention at the population level.

Source: Li, H., Chee, C.B., Geng, T., Pan, A. and Koh, W.P., 2022. Joint associations of multiple lifestyle factors with risk of active tuberculosis in the population: the Singapore Chinese Health Study. Clinical Infectious Diseases, 75(2), pp.213-220.