Dear editor
Huang et al conducted a meta-analysis of published studies on various aspects of association between vitamin D and tuberculosis (TB).Citation1 The study concluded that vitamin D deficiency (VDD) was associated with higher risk of TB. However, low body mass index (BMI), a well-recognized and a stronger risk factor of TB than VDD, was not mentioned in this review nor was it accounted for in the multivariable analysis in the majority of case–control studies included in the meta-analysis exploring the association between TB and VDD. Vitamin D levels are likely to be positively correlated with weight/BMI. Infected people who are underweight by ≥15%, 10%–14% and 5%–9% are at increased risk of progression to TB disease with 2.6, 2.0 and 2.2 cases per 1,000 person-year, respectively.Citation2 Contradictory results were found in the few studies of this meta-analysisCitation1 that considered weight/BMI in the multivariable analysis. One study showed a weak association between VDD and TB (odds ratio: 1.07, 95% confidence interval 1.01–8.52) but only in men.Citation3 Another study found no such association.Citation4
Protein-calorie malnutrition is recognized as a well-established risk factor of TB disease, if not the strongest.Citation5 Some studies in the meta-analysisCitation1 consistently showed that TB patients have lower weight/BMI as compared to controls and therefore this should always be considered in the multivariable analysis assessing nutritional risk factors of TB. Besides low levels of vitamin D, underweight TB patients likely have low levels of other vitamins, calcium, albumin, ferritin or cholesterol (to mention a few) as shown by some studies included in Huang et al meta-analysis.Citation1
Future studies focusing on nutritional deficiency risk factors for TB should consider all of these factors together and/or independently as playing a role.
Disclosure
The author reports no conflicts of interest in this communication.
References
- HuangSJWangXHLiuZDVitamin D deficiency and the risk of tuberculosis: a meta-analysisDrug Des Devel Ther201711 91 102
- Targeted tuberculin testing and treatment of latent tuberculosis infection. This official statement of the American Thoracic Society was adopted by the ATS Board of Directors, July 1999. This is a Joint Statement of the American Thoracic Society (ATS) and the Centers for Disease Control and Prevention (CDC). This statement was endorsed by the Council of the Infectious Diseases Society of America. (IDSA), September 1999, and the sections of this statementAm J Respir Crit Care Med20001614 Pt 2 S221 S24710764341
- Ho-PhamLTNguyenNDNguyenTTAssociation between vitamin D insufficiency and tuberculosis in a Vietnamese populationBMC Infect Dis201010 30620973965
- WejseCOlesenRRabnaPSerum 25-hydroxyvitamin D in a West African population of tuberculosis patients and unmatched healthy controlsAm J Clin Nutr2007865 1376 138317991649
- KoetheJRvon ReynCFProtein-calorie malnutrition, macronutrient supplements, and tuberculosisInt J Tuberc Lung Dis2016207 857 86327287634