Undernutrition may make people more susceptible to TB

Undernutrition has been singled out as a potential risk factor for tuberculosis (TB) in a recent Cochrane review.

Random‐effects meta‐analysis of data from 51 cohort studies with over 27 million participants indicated that people with undernutrition faced a more than twofold increase in the risk of TB (hazard ratio [HR], 2.23, 95 percent confidence interval [CI], 1.83–2.72; prediction interval, 0.98–5.05; 23 studies, n=2,883,266), although the certainty of the evidence was low due to a moderate risk of bias across studies and inconsistency. [Cochrane Database Syst Rev 2024;6:CD015890]

Results were consistent across studies with a follow-up period under 10 years (HR, 2.02, 95 percent CI, 1.74–2.34; prediction interval, 1.20–3.39; 22 studies, n=2,869,077), with a moderate certainty of evidence owing to a moderate risk of bias across studies.

The sole study with long-term follow-up (≥10 years) had a higher risk estimate and a wider CI (HR, 12.43, 95 percent CI, 5.74–26.91; n=14,189), in addition to having a low certainty of evidence due to the moderate risk of bias and indirectness.

Across studies that reported either odds ratio or risk ratio, the pooled values indicated an association between undernutrition and TB (odds ratio, 1.56, 95 percent CI, 1.13–2.17; prediction interval, 0.61–3.99; 8 studies, n=173,497; risk ratio, 1.95, 95 percent CI, 1.72–2.20; prediction interval, 1.49–2.55; 4 studies, n=1,475,867). However, the certainty of evidence was low or very low due to the high risk of bias and inconsistency.

The included studies were conducted in countries across the six World Health Organization (WHO) regions. Twenty-five studies involved people living with HIV, which were mainly conducted in the African region. Most studies were in adults, four in children, and three in children and adults.

While undernutrition was assessed using established criteria, eight studies did not confirm TB diagnoses with either culture tests or WHO-approved rapid diagnostic tests. The median follow‐up duration was 3.5 years, and most of the studies reported an adjusted hazard ratio from a multivariable Cox‐proportional hazard model.

“Undernourishment, also referred to as undernutrition, is the deficient intake of essential nutrients resulting from either a lack of food or an imbalanced diet that does not provide adequate quantities of the necessary calories, macronutrients, or micronutrients,” the investigators said. [https://globalnutritionreport.org/reports/2020-global-nutrition-report]

Based on WHO estimates, around 148 million children under 5 years were too short for their age (stunted) while 45 million were too thin for their height (wasted) in 2022. Latest data on adults showed that roughly 9 percent of those over 20 years of age were underweight in 2016. [https://data.unicef.org/resources/jme-report-2023/; Lancet 2017;390:2627-2642]

The State of Food Security and Nutrition in the World Report 2023 estimated that a staggering total of between 691 and 783 million people suffered hunger in 2022, with the problem further exacerbated by ongoing conflicts, climate extremes, economic disruptions, and the lingering financial effects of the pandemic. [https://www.fao.org/documents/card/en?details=cc3017en]

“Policies targeted towards the reduction of the burden of undernutrition are not only needed to alleviate human suffering due to undernutrition and its many adverse consequences but are also an important part of the critical measures for ending the TB epidemic by 2030,” the investigators said.

“Large population‐based cohorts, including those derived from high‐quality national registries of exposures (undernutrition) and outcomes (TB disease), are needed to provide high‐certainty estimates of this risk across different settings and populations, including low‐ and middle‐income countries from different WHO regions,” they continued, adding that studies including children and adolescents and state‐of‐the‐art methods for diagnosing TB should be able to provide more up‐to‐date information relevant to practice and policy.