Introduction: The results of this epidemiological study demonstrate the burden of 25-hydroxyvitamin D deficiency in two sunny Mediterranean countries Greece and Cyprus- and some of the related risk factors. These two populations were examined together due to their common phylogenetic origin. Up until now there are no available data for the mean Vitamin D levels of the Cypriot adult population. An early identification of vitamin D deficiency is now considered as the cornerstone of preventive medicine.
Materials and methods: Vitamin D levels for 8780 Greek and 2594 Cypriot subjects were blindly collected from the hospitals laboratory information systems over a 5-year time period. Sex, age, the month at which the blood sample was drawn, and accompanying diseases (recorded just for 870 patients in the Greek database) were also collected. These data were obtained respectively from the tertiary health care center AHEPA in Thessaloniki, Greece (latitude; N40.7°, longitude; E22.9°) and AGIOS LOUKAS a primary health care center in Nicosia, Cyprus (latitude; N35.1°, longitude; E33.3°). In order to examine the relationship between potential risk factors and vitamin D levels univariate analysis and multivariate linear regression analysis were performed.
Results: 73.07% of the Greek and 69.28% of the Cypriot subjects of the sample had inadequate levels of vitamin D. The mean 25(OH)D value for the Greek subjects was found 25.08 ng/ml and for the Cypriots 25.37 ng/ml. The highest levels in both databases were recorded for the month September. For, both databases the multivariate linear regression models demonstrated that age and month were significantly associated with 25(OH)D levels. Sex was significantly associated only in the Greek database (P<0.0001). In the second multivariate linear regression model- which included just the subgroup of patients with a recorded disease- the month was not associated with 25(OH)D levels (P=0.235). Amongst the recorded diseases growth retardation, hypercalcemia, sickle cell anemia, polyneuropathy (all P<0.01), mental retardation and MS (both P<0.05) were related with 25(OH)D levels.
Conclusions: The prevalence of vitamin D deficiency is extremely high in both population samples and particularly in subjects with chronic diseases. However, the cross-sectional design of the study cannot prove causality and further prospective studies in healthy subjects are necessary.
19 May 2018 - 22 May 2018