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.