The relationship between vitamin D status and disease activity in Iraqi systemic lupus erythematosus patients.

Objective: To find the relationship between vitamin D deficiency and the activity of systemic lupus erythematosus in Iraqi patients.

Methods: The case-control study was conducted at Baghdad Teaching Hospital, Baghdad, Iraq, from July to October 2018, and comprised systemic lupus erythematosus patients regardless of age and gender visiting the Rheumatology outpatient clinic. Serum levels of complement protein 3, complement protein 4, anti-doublestranded deoxyribonucleic acid and 25-hydroxy vitamin D were estimated. Based on disease activity scores, patients were divided into moderate activity group SLE-M and severe activity group SLE-S. Healthy subjects matched for age and gender were also enrolled as the control group. Data was analysed using Graph Pad Prism 5.0.

Results: Of the 150 subjects, 62(41.3%) were in SLE-S group, 38(25.3%) in SLE-M and 59(33.3%) in the control group. Among the patients, 97(97%) were females and 3(3%) were males, with a female-to-male ratio of 32:1. The patients' age range was <10-≥50 years, while the control group consisted of 2 (4%) males and 48 (96%) females with an age range of <10-≥50. The mean levels of serum complement protein 3, complement protein 4 and vitamin D levels were significantly lower in the patient groups compared to the controls (p<0.05).

Conclusions: Systemic lupus erythematosus patients suffered from either vitamin D deficiency or insufficiency, and low vitamin D levels were found related to disease activity.