Mass screening is more effective than passive detection for identifying tuberculosis (TB) infection in older adults, primarily due to higher detection rates among asymptomatic individuals and those with limited health care access. These study results were published in Clinical Infectious Diseases.
A mass TB screening intervention was performed among individuals older than 60 years in Lanxi County, China. Mass TB screening comprised standardized questionnaires, physical examination, and chest x-ray. Study participants with chest x-rays results suggestive of TB infection underwent subsequent sputum smear testing for further evaluation. Data also were captured from older adults diagnosed with TB infection via passive detection during the same time period. Researchers assessed the prevalence of TB infection per 100,000 persons across 3 age groups (60-69, 70-80, and ≥80 years). They compared the presence and duration of TB symptoms prior to diagnosis between participants in the mass screening group and those in the passive detection group. Access to health care was also compared between the groups.
There were 49,339 participants in the mass screening group, representing a screening coverage rate of 32.2% of the eligible population. Of participants who underwent mass TB screening, 43% were aged between 60 and 69 years, 46% were aged between 70 and 80 years, 54% were women, 78% were farmers, 13% had diabetes, and 3% previously had TB infection.
Overall, 115 participants were diagnosed with TB infection via mass screening, representing a prevalence rate of 233 (95% CI, 194-279) per 100,000 persons. The total number needed to screen to identify 1 participant with TB infection was 430 (95% CI, 357-526). In addition, the prevalence of TB infection per 100,000 persons was higher among men vs women (394 vs 94) and those with vs without diabetes (391 vs 209).
Among 103,979 participants who were not included in the mass screening event, 168 were diagnosed with TB infection via passive detection. All individuals diagnosed via passive detection had at least 1 TB-related symptom. The overall prevalence-to-case notification ratio was 1.44 (95% CI, 1.14-1.84). In addition, a high prevalence-to-case ratio was observed among men (1.71; 95% CI, 1.20-2.44) and those aged between 60 and 70 years (1.77; 95% CI, 1.09-2.89).
The identification of TB infection was more common via mass screening than passive detection among participants who smoked (adjusted odds ratio [aOR], 2.43; 95% CI, 1.15-5.17) and those with diabetes (aOR, 4.72; 95% CI, 2.17-10.91). Mass screening also was more likely to detect TB infection among participants with limited health care access (aOR, 4.52; 95% CI, 1.35-21.28).
Limitations of this study include potential misclassification of chest x-ray findings, the inclusion of only older adults, potential selection bias, and the high rate of bacteriologically-negative TB diagnoses.
According to the researchers “Half of persons with tuberculosis during mass screening were asymptomatic, encompassing most of the detection gap compared to background detection.”
References:
Hu Z, Liu K, Zhou M, et al. Mass tuberculosis screening among the elderly: a population-based study in a well-confined rural county in eastern China. Clin Infect Dis. Published online July 28, 2023. doi:10.1093/cid/ciad438
Source: Infectious Disease Advisor