European multicentre pilot survey to assess vitamin D status in rheumatoid arthritis patients and early development of a new Patient Reported Outcome questionnaire (D-PRO).

OBJECTIVE: To collect data on vitamin D (25(OH)D) serum levels in a large number of rheumatoid arthritis (RA) patients from different European countries, to investigate their relation with disease activity, disability, quality of life, and possibly to construct a new Patient Reported Outcome (PRO) questionnaire in order to self-estimate if they are at risk for vitamin D insufficiency/deficiency-related clinical implications (D-PRO).

METHODS: This was a European League Against Rheumatism (EULAR) supported cross-sectional study (project No CLI064) which involved 625 RA patients (mean age 55±11years, mean disease duration 11±9years), 276 age and sex matched healthy subjects, and rheumatologists working in academic institutions or hospital centres, as well as PARE organizations (patient representatives) from 13 European countries. Serum samples for 25(OH)D level measurement were collected during winter time and analyzed in a central laboratory using chemiluminescence immunoassay (DiaSorin). Patient past medical history was recorded. RA patients were provided with three questionnaires: the Rheumatoid Arthritis Impact Diseases score (RAID), the Health Assessment Questionnaire (HAQ), and the new D-PRO questionnaire at the time of 25(OH)D serum sampling. D-PRO questionnaire consisted of three domains, Symptom Risk Score (SRS), Habitus Risk Score (HRS) and Global Risk Score (SRS+HRS=GRS), constructed with items possibly related to vitamin D deficiency. D-PRO was correlated with both clinical and PRO scores. DAS28-CRP was also evaluated. Statistical analysis was performed by non parametric tests.

RESULTS: Mean serum concentration of 25(OH)D in RA patients (17.62±9.76ng/ml) was found significantly lower if compared to the levels obtained in matched controls (18.95±9.45ng/ml) (p=0.01), with statistically significant differences among several European countries. Negative correlations were found between 25(OH)D serum levels and DAS28-CRP (p<0.001), RAID (p=0.05) and HAQ (p=0.04) scores in the RA patients group. Negative correlations were also found in the cohort of enrolled RA patients between 25(OH)D serum concentrations and SRS (p=0.04), HRS (p=0.02) and GRS (p=0.02) domains of the D-PRO questionnaire.

CONCLUSIONS: This first multicentre European survey add new evidences that vitamin D insufficiency/deficiency is frequent in RA patients with statistically significant differences among several countries. Vitamin D serum concentrations seem to correlate negatively and significantly with the D-PRO Global Risk Score, clinimetric indexes for quality of life, disease activity and disability in present cohort of RA European patients.