An epidemiological evaluation of risk factors for tuberculosis in South India: a matched case control study

There are limited data on risk factors associated with tuberculosis (TB) in India.

To evaluate potential socio-demographic risk factors for TB.

Matched case-control. Cases were all new diagnoses of pulmonary TB attending as out-patients at St John's Medical College Hospital, Bangalore, India, from October 2001 to October 2003. Age- and sex-matched controls, one for each case (n = 189), were recruited among relatives accompanying non-TB in-patients in the hospital.

Significant risk factors were low education level (OR 0.30; 95%CI 0.11-0.82), not having a separate kitchen (OR 3.26; 95%CI 1.25-8.46) and chronic disease, mainly diabetes (OR 2.44; 95%CI 1.17-5.09). High income, cooking with biomass fuels, history of smoking and alcohol consumption were not significant on multivariate analysis. Patients were respectively 11 and seven times more likely to have a BMI <18.5 (95%CI 5.62-21.98) and mid-arm circumference <24 cm (95%CI 3.87-11.89).

In our study, TB was associated with low education level, kitchen type and diabetes, reflecting the complex interaction between non-communicable disease, urbanisation and a changing economic climate in Bangalore. The relationship between TB, the use of biomass cooking fuels and gender differentials related to fuel exposure merit further exploration. The study underscores the poor nutritional status of patients.