Publication:

Vitamin D levels in systematic lupus erythematosus patients: association with disease activity index and interferon alpha

Background In different studies the correlation between systemic lupus erythematosus (SLE) and disease activity with vitamin D has been shown. The role of different interferons especially interferon alpha (IFN-α) in lupus pathogenesis have been previously shown. Considering the role of vitamin D and IFN-α, it is possible that these two could demonstrate the SLE activity. This study aimed to investigate the association between vitamin D levels and IFN-α with disease activity index in Ardabil city SLE patients.

Methods In this case control study, 50 SLE patients and 50 age and sex matched healthy subjects were recruited. Patients had serum 25-OH Vitamin D concentration and disease activity recorded. Vitamin D and IFN-α levels were compared between two groups and also, levels of anti-dsDNA, and SLEDAI in case group was measured. Statistical methods were used to determine the correlation between vitamin D and IFN-α with disease activity index at baseline.

Results Vitamin D deficiency (<40 nmol/L) was detected in 20% of SLE patients. Vitamin D level in case group significantly lower than control group (23.94±11.93 vs. 29.10±11.40 ng/ml, p=0.02). The IFN-α amount in case group significantly upper than control group (396.60±54.73 vs. 200.38±14.42, p=0.001). There was significantly negative correlation between vitamin D with IFN-α (r=-0.413, p=0.003), SLEDAI (r=-0.492, p<0.001) and anti-dsDNA (r=-0.417, p=0.003). There was positive correlation between IFN-α with SLEDAI (r=0.358, p=0.01) and anti-dsDNA (p=0.297, p=0.03).

Conclusions Results showed that the low vitamin D was associated with a higher disease activity in SLE patients. Also, it seems that, the improvement of vitamin D levels by decreasing IFN-α could help in controlling disease activity in future.