Sample Size Calculation
This is the first study to compare the serum level of vitamin B12
between patients with VVS and healthy controls in the adult age group.
Hence, we calculated the sample size from a similar study on adolescents
showing that 47.2% of patients with VVS had vitamin B12 deficiency
compared to 18.0% of the control group.22 To achieve
a power of 80%, we need 39 patients in each group to reach a
statistical significance level of 0.05.