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Vitamin D insufficiency linked to lower virologic response in HBV

Patients with lower levels of vitamin D showed a lower virologic response to chronic hepatitis B treatment and researchers connected geographic latitude, genetic variants and sex to the patients’ vitamin D status.

“These findings further improved our understanding of vitamin D insufficiency and reminded investigators to take into account of geographical and genetic factors when interpreting such data,” the researchers wrote. “As a promising and relatively safe nutrient, vitamin D status merits continued investigation on its immunomodulatory role and its interaction with HBV.”

From August 2009 to March 2012, researchers the measured serum 25(OH)D levels of 560 patients, 308 of whom had vitamin D insufficiency (25(OH)D levels < 30 ng/mL). The patients received treatment for 104 weeks with Tyzeka (telbivudine, Novartis) or telbivudine plus adefovir.

Those with vitamin D insufficiency had a significantly lower rate of virologic response (67.2% vs. 81.7%; P < .001).

Mean 25(OH)D levels were significantly lower according to distance from the equator: 35.95 ng/mL in Southern China, 29.06 in ng/mL in Central China and 24.44 ng/mL in Northern China (P < .001).

“Sunlight is an important determinant of vitamin D status via its initial generation in the skin,” the researchers wrote, “thereby the result is possibly attributable to the different chance of UV exposure in different latitude area.”

Genetics were also an important variable. The researchers observed significantly lower 25(OH)D levels in patients with genotype AA compared with AC or CC among GC rs7041 (P = .001) and rs 4588 polymorphisms (P = .006). For GC rs2282679, 25(OH)D levels were higher in patients with AA genotype compared with patients with AC or CC genotype (P = .001).

Further analysis showed that male vs. female sex (OR = 2.312; 95% CI, 1.411-3.787), blood sampling taken during winter or spring vs. summer or autumn (OR = 1.536; 95% CI, 1.07-2.221), and location in Northern China vs. Central China (OR = 0.454; 95% CI, 0.288-0.715) or Southern China (OR = 0.164; 95% CI, 0.98-0.276) were independent factors of vitamin D insufficiency.

Variables associated with virologic response included vitamin D levels of 30 ng/mL or higher (OR = 0.458; 95% CI, 0.207-0.682), alanine aminotransferase (OR = 1.161; 95% CI, 1.049-1.285), HBV DNA (OR = 0.413; 95% CI, 0.31-0.551) and HBsAg levels (OR = 0.409; 95% CI, 0.287-0.583) and treatment with telbivudine plus adefovir vs. telbivudine monotherapy (OR = 0.435; 95% CI, 0.295-0.642).

“The results presented here not only strengthened the role of genetic factors in regulation of vitamin D status, but also confirm that differences in genetic determinants exist in different racial or ethnic groups,” the researchers concluded. – by Talitha Bennett

Disclosure: Healio.com/Hepatology was unable to determine relevant financial disclosures at the time of publication.