We were highly interested in the editorial “Vitamina D y enfermedades autoinmunes reumáticas” (“Vitamin D and autoimmune rheumatic disease”), published recently in Reumatología Clínica.1 At the present time, it is well-known that vitamin/hormone D has an essential role in the regulation of the immune system,2 and that its deficiency is related to the presence of inflammation, autoimmunity, cancer and atherosclerosis.3 This is especially interesting, when we learn that the levels of vitamin D are substantially reduced in western countries and in the Spanish population in particular.4

As the authors of the editorial do point out, the deficiency or insufficiency of vitamin D is related not only to the coexistence of autoimmune diseases like systemic lupus erythematosus or rheumatoid arthritis (RA), but also to the activity of some of these diseases.5–7 The role that vitamin/hormone D may have in other chronic inflammatory diseases, like ankylosing spondylitis (AS) or psoriatic arthritis (PsA), is less well-known.

Recently, we published the baseline data on cardiovascular morbidity and levels of vitamin/hormone D in patients included in the CARMA (“CARdiovascular in rheuMAtology”) project.8,9 The proposal is a prospective Spanish study, promoted by the Sociedad Española de Reumatología (SER), in which we evaluate the risk of developing a fatal cardiovascular event after 10 years in patients with RA, AS and PsA, compared to a cohort of patients with no inflammatory diseases, followed in rheumatology clinics of 67 Spanish hospitals. The study includes a total of 2234 patients: 775 RA, 738 AS and 721 PsA, in addition to 677 noninflammatory individuals, with degenerative or soft tissue diseases.8,9

In the baseline analysis, we found that the patients with inflammatory diseases had a more marked deficiency of D (25-OH-vitamin D<20ng/mL), than the noninflammatory patients (40.5% in RA; 40% in AS; 41% in PsA; and 26.7% in the control group; [P<.001]). The mean levels of 25-OH-vitamin D were: 20.4ng/mL in RA; 20.9ng/mL in AS; 20ng/mL in PsA; and 24.8ng/mL in the control group. We should point out that the controls included, mostly, patients with osteoarthritis, osteoporosis, low back pain or soft tissue disease, in which vitamin/hormone D is usually reduced, as we confirmed, although with fewer percentage points of deficiency.9

With respect to the activity and severity, the bivariate study demonstrated a significant association between the vitamin/hormone D deficiency and certain parameters for aggressive disease. This association disappeared in the adjusted model, although there persisted a certain associative trend between the vitamin/hormone D deficiency and the presence of anti-cyclic citrullinated peptide antibodies (adjusted odds ratio [OR]: 1.45; 95% confidence interval [CI]: 0.99–2.12; P=.056) and Bath AS Functional Index (adjusted OR: 1.08; 95% CI: 0.99–1.17; P=.070)9 in RA and AS, respectively. However, we also point out that patients with inflammatory diseases are closely controlled in hospital rheumatology units, and between 40% and 47.4% are receiving biologic therapy, with activity reduced to their inclusion in the study (disease activity score 28 joints–erythrocyte sedimentation rate of 3.2 in RA and 3.0 in PsA; Bath AS Disease Activity Index 3.5 in AS).9

Although our work has certain limitations and there are still doubts concerning supplementation in patients with vitamin/hormone D deficiency, in particular, those with chronic inflammatory diseases, as to, whether, it improves their health and reduces inflammatory activity.10 We feel, like the authors of the editorial, that it is important to monitor and supplement these patients, especially those with a moderate/serious deficiency, because of the possible pathogenic role that vitamin/hormone D may have in the course and comorbidity of their underlying disease.

Finally, it must still be determined whether the maintenance of low vitamin D levels increments the incident of cardiovascular events in our cohort. This is one of the objectives of the CARMA study, and is to be analyzed in the next few years.