A prospective cross-sectional study of tuberculosis in elderly Hispanics reveals that BCG vaccination at birth is protective whereas diabetes is not a risk factor.

Julia M Scordo,Jose A Caso,Blanca I Restrepo,Doris Ayala,Francisco Mora-Guzmán,Eder Ledezma-Campos,Larry S Schlesinger,Joanne Turner,Ana Paulina Quirino-Cerrillo,Génesis P Aguillón-Durán,Eminé Rodríguez-Reyna,Jordi B Torrelles,Frederick Quinn

doi:10.1371/journal.pone.0255194

Abstract

BackgroundAging increases the risk of tuberculosis (TB) and its adverse outcomes, but most studies are based on secondary analyses, and few are in Hispanics. Diabetes is a risk factor for TB in adults, but its contribution in the elderly is unknown. We aimed to identify the role of diabetes and other risk factors for TB in elderly Hispanics.MethodsCross-sectional study among newly-diagnosed TB patients, recent contacts (ReC), or community controls (CoC) totaling 646 participants, including 183 elderly (>60 years; 43 TB, 80 ReC, 60 CoC) and 463 adults (18 to 50 years; 80 TB, 301 ReC and 82 CoC). Host characteristics associated with TB and latent Mycobacterium tuberculosis infection (LTBI) were identified in the elderly by univariable and confirmed by multivariable logistic regression.ResultsLTBI was more prevalent among the elderly CoC (55% vs. 23.2% in adults; p<0.001), but not in ReC (elderly 71.3% vs. adult 63.8%); p = 0.213). Risk factors for TB in the elderly included male sex (adj-OR 4.33, 95% CI 1.76, 10.65), smoking (adj-OR 2.55, 95% CI 1.01, 6.45) and low BMI (adj-OR 12.34, 95% CI 4.44, 34.33). Unexpectedly, type 2 diabetes was not associated with TB despite its high prevalence (adj-OR 0.38, 95% CI 0.06, 2.38), and BCG vaccination at birth was protective (adj-OR 0.16, 95% CI 0.06, 0.45).ConclusionsWe report novel distinctions in TB risk factors in the elderly vs. adults, notably in diabetes and BCG vaccination at birth. Further studies are warranted to address disparities in this vulnerable, understudied population.

Highlights

Aging is associated with immune function decline consequent to cellular immunosenescence and inflammaging, and is identified as a risk factor for respiratory tract infections such as tuberculosis (TB) [1, 2]
latent Mycobacterium tuberculosis infection (LTBI) was more prevalent among the elderly community controls (CoC) (55% vs. 23.2% in adults; p
Risk factors for TB in the elderly included male sex, smoking and low body mass index (BMI)

Summary

Introduction

Aging is associated with immune function decline consequent to cellular immunosenescence and inflammaging, and is identified as a risk factor for respiratory tract infections such as tuberculosis (TB) [1, 2]. Patients are difficult to diagnose due to the lack of classical symptoms and to impaired or reduced responses to diagnostics such as the tuberculin skin test. This leads to frequent delays in treatment initiation and in some cases to post-mortem diagnosis [7,8,9].

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