Evaluating low and high vitamin D levels in Ecuadorian cities from 2018 to 2022: interrupted time series and a cross-sectional study

Objectives To identify differences in the mean vitamin D concentrations in samples obtained from a private laboratory in Quito and to explore their relationship with the pre-pandemic and pandemic periods spanning from 2018 to 2022. Design A combination of an interrupted time series design and a retrospective cross-sectional approach. Setting and participants The study involved 9285 participants who had their 25-hydroxyvitamin D (25(OH)D) levels tested at a well-known private laboratory in Quito, Ecuador, from 2018 to 2022. Primary and secondary outcome measures The 25(OH) D levels were analysed and assessed for correlations with age, and the year the measurements were taken. Results The mean 25(OH)D level was 27.53 ng/mL (± 14.11). Approximately 68.8% of participants had serum 25(OH)D levels of less than 30 ng/mL, and 0.6% showed potential harm from excess 25(OH)D, with levels over 100 ng/mL. The analysis indicated a significant monthly increase of 0.133 units in 25(OH)D levels (p=0.006). However, the period after March 2020, compared with before, saw a non-significant decrease of 1.605 units in mean 25(OH)D levels (p=0.477). Conclusions The study's findings indicate a significant prevalence of 25(OH)D deficiency, underscoring the necessity for preventative measures. However, the increasing trend in high 25(OH)D levels is concerning, emphasising the importance of prudent vitamin D supplement prescriptions and public education against self-medication. For efficient resource allocation and targeting of those with higher risks, it may be advantageous to concentrate vitamin D testing on specific population groups.