Introduction: Factors associated with tuberculosis (TB) in Kerala, the southern Indian state that notifies approximately 33 microbiologically confirmed new cases per 100,000 population every year for the past two decades, are still unclear. We did a community-based case-control study in Kollam district, Kerala, to identify the individual-level risk factors for TB.
Methods: Structured questionnaire was applied to 101 microbiologically confirmed new TB cases registered under Revised National Tuberculosis Control Program and 202 age- and gender-matched neighborhood controls without present or past TB. Information was sought on socioeconomic status (SES), smoking, consumption of alcohol, close contact with active TB during childhood or recent past, diabetes mellitus (DM), and other comorbid conditions.
Results: Close contact with TB during childhood [odds ratio (OR) 15.88, 95% confidence interval (CI) 3.21-78.55], recent close contact with TB (OR 4.81, 95% CI 2.09-11.07), DM (OR 1.64, 95% CI 1.04-3.06), SES (OR 2.16, 95% CI 1.16-4.03), smoking more than 10 cigarettes/beedis per day (OR 3.32, 95% CI 1.27-8.96), consuming more than 10 standard drinks per week (OR 2.91, 95% CI 1.33-6.37), and the interaction term of having close contact with TB during childhood and DM at present (OR 7.37, 95% CI 1.18-50.29) were found to be associated with TB.
Conclusion: Close contact with a case of TB, presence of DM, lower SES, smoking, and alcohol consumption were associated with active TB in Kollam. Having close contact with a case of TB during childhood and development of DM in later life together are significantly associated with active TB in the study population. The findings also direct further studies to confirm and explore mechanisms of interaction of diabetes with childhood exposure to TB.