Silicosis as a predictor of tuberculosis mortality and treatment failure and need for incorporation in differentiated TB care models in India

Abstract

Background Differentiated tuberculosis (TB) care is an approach to improve treatment outcomes by tailoring TB management to the particular needs of patient groups based on their risk profile and comorbidities. In silicosis-prone areas, the coexistence of TB and silicosis may exacerbate treatment outcomes. The objective of the study was to determine predictors of TB-related mortality, treatment failure, and loss to follow-up in a silicosis-prone region of western India. Methods A retrospective cohort was conducted among 2748 people with TB registered between January 2006 and February 2022 in Khambhat, a silicosis-prone block in western India. Death, treatment failure, and loss to follow up were the outcome variables. The significant predictors of each outcome variable were determined using multivariable logistic regression and reported as adjusted odds ratios (aOR) with 95% confidence intervals (CIs). Results In the cohort of 2,748 people with TB, 5% presented with silicosis, 11% succumbed to the disease, 5% were lost to follow-up during treatment, and 2% encountered treatment failure upon completion of therapy. On multivariable logistic regression, concomitant silicosis [aOR 2.3 (95% CI 1.5–3.5)], advancing age [aOR 1.03 (95% CI 1.02–1.04)], male gender [aOR 1.4 (95% 1.1–1.9)], human immunodeficiency virus (HIV) positive [aOR 2.2 (95% 1.02–4.6)], and previous TB treatment [aOR 1.5 (95% CI 1.1–1.9)] significantly predicted mortality among people with TB. Concomitant silicosis [aOR 3 (95% CI 1.4–6.5)], previous TB treatment [aOR 3 (95% CI 2–6)], and multi-drug resistant TB [aOR 18 (95% CI 8–41)] were the significant predictors of treatment failure on adjusted analysis. Advancing age [aOR 1.012 (1.001–1.023)], diabetes [aOR 0.6 (0.4–0.8)], and multi-drug resistance [aOR 6 (95% CI 3–12)] significantly predicted loss to follow-up after adjusting for confounders. Conclusions Controlling silicosis might decrease TB mortality and treatment failure in silicosis-prone regions. The coexistence of HIV and silicosis may point to an increase in TB deaths in silicosis-prone areas. Silicosis should now be acknowledged as a major comorbidity of TB and should be included as one of the key risk factors in the differentiated TB care approach. Primary care physicians should have a high clinical suspicion for silicosis among individuals diagnosed with TB in silicosis-prone blocks.

The systemic immune-inflammation index is significantly associated with the severity of silicosis: a 9-year retrospective study in Beijing

“…However, it is worth noting that the clinical application of the SII is somewhat limited by the fact that blood-based inflammatory indexes are not specific, as they may elevate with respiratory infection or other inflammatory conditions. In addition, tuberculosis, a common complication of silicosis ( 29 , 30 ), also may potentially alter the inflammatory markers. Therefore, in order to avoid the nonspecific effects of SII, we set strict inclusion and exclusion criteria for the patients’ enrollment, excluding pneumonia, tuberculosis, other infectious diseases, and any condition that could affect hematologic indexes, so as to make the results of the association between SII levels and the severity of silicosis more objective.…”

Accuracy of chest x-ray screening of silica-exposed miners for tuberculosis

“…This is often difficult, but with appropriate use of Xpert, a focused occupational history, treatment of intercurrent respiratory illness and follow-up with repeat assessment, some proportion of unneeded empirical treatment could be avoided. This approach would have the additional benefits of (a) taking into account the potentially adverse effect of silicosis on TB treatment outcomes and (b) early identification of silicosis for purposes of access by ex-miners to compensation [ 30 , 31 ].…”

Framework for implementing collaborative TB-silicosis activities in India: insights from an expert panel

“…TB increases the risk of death among patients with silicosis [24][25][26]. Silicosis, in turn, exacerbates TB treatment outcomes by increasing the risk of death, relapse, treatment failure, and interruptions [27][28][29]. Additionally, the coexistence of TB and silicosis poses considerable diagnostic challenges due to the difficulty in distinguishing their clinical and radiological presentations [30].…”