Revisiting the association between vitamin D deficiency and active tuberculosis: A prospective case-control study in Taiwan

Background

To revisit the association between vitamin D deficiency (VDD, defined as serum 25(OH)D < 20 ng/ml) and incident active tuberculosis (TB), after two potentially underpowered randomized trials showed statistically non-significant 13%–22% decrease in TB incidence in vitamin D supplementation groups.

Methods

We prospectively conducted an age/sex-matched case–control study that accounting for body-mass index (BMI), smoking, and other confounding factors to examine the association between VDD and active TB among non-HIV people in Taiwan (latitude 24°N), a high-income society which continues to have moderate TB burden.

Results

We enrolled 62 people with incident active TB and 248 people in control group. The TB case patients had a significantly higher proportion of VDD compared to the control group (51.6% vs 29.8%, p = 0.001). The 25(OH)D level was also significantly lower in TB patients compared to control group (21.25 ± 8.93 ng/ml vs 24.45 ± 8.36 ng/ml, p = 0.008). In multivariable analysis, VDD (adjusted odds ratio [aOR]: 3.03, p = 0.002), lower BMI (aOR: 0.81, p < 0.001), liver cirrhosis (aOR: 8.99, p = 0.042), and smoking (aOR: 4.52, p = 0.001) were independent risk factors for incident active TB.

Conclusions

VDD is an independent risk factor for incident active TB. Future randomized trials examining the effect of vitamin D supplementation on TB incidence should focus on people with a low BMI or other risk factors to maximize the statistical power.