Individuals' Vulnerability Based Active Surveillance for TB: Experiences from India

Community-based active TB case finding (ACF) has become an essential part of TB elimination efforts in high-burden settings. In settings such as the state of Kerala in India, which has reported an annual decline of 7.5% in the estimated TB incidence since 2015, if ACF is not well targeted, it may end up with a less-than-desired yield, the wastage of scarce resources, and the burdening of health systems. Program managers have recognized the need to optimize resources and workloads, while maximizing the yield, when implementing ACF. We developed and implemented the concept of 'individuals'-vulnerability-based active surveillance' as a substitute for the blanket approach for population/geography-based ACF for TB. Weighted scores, based on an estimate of relative risk, were assigned to reflect the TB vulnerabilities of individuals. Vulnerability data for 22,042,168 individuals were available to the primary healthcare team. Individuals with higher cumulative vulnerability scores were targeted for serial ACF from 2019 onwards. In 2018, when a population-based ACF was conducted, the number needed to screen to diagnose one microbiologically confirmed pulmonary TB case was 3772 and the number needed to test to obtain one microbiologically confirmed pulmonary TB case was 112. The corresponding figures in 2019 for individuals'-vulnerability-based ACF were 881 and 39, respectively. Individuals'-vulnerability-based active surveillance is proposed here as a practical solution to improve health system efficiency in settings where the population is relatively stationary, the TB disease burden is low, and the health system is strong.

Population Attributable Risk of Tuberculosis Vulnerabilities in Kerala, India

Background

A robust disaggregated understanding of the determinants of tuberculosis (TB) in each local setting is essential for effective health system and policy action to control TB.

Objectives

The objective of the study was to identify population attributable risk (PAR) for TB disease based on the locally available evidences for Kerala, India.

Methods

Systematic review was done for risk factors of TB in the state. The second set of searches was done to understand the prevalence of the identified risk factors in general population in Kerala. With all available studies and reports, an expert group consensus was made to finalize state-specific prevalence of risk factors. Population attributable fractions were calculated for identified risk factors.

Results

PAR for TB disease in Kerala obtained was 24% for undernutrition, 15% for diabetes, 15% for tobacco use, and 1% for HIV.

Conclusion

Kerala state's PAR for TB was comparatively lower for HIV but higher for diabetes mellitus. Similar exercises for summarizing population risk factors need to happen at all states for making plans to effectively combat TB.

Higher risk of developing active TB among adult diabetics exposed to TB during childhood: A study from Kerala, India

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.