2.1. Study design and sample size calculation
This study was approved by the Istanbul Aydin University Clinical Research Ethics Committee with B.30.2.AYD.0.00.00-480.2/217 protocol number before the research. The statistical power analysis was showed that a minimum sample of n=73 in each group would have the assumption of 95% CI and power of 80%. A nominal α=0.05 and two-tailed tests were used in the power calculations.
We recruited a total of 117 schizophrenia patients aged 18 – 65 years as a case group. For each schizophrenia patient, one healthy control people were recruited. Individuals in the control group were randomly selected from the city where the patients lived (Istanbul, Turkey) and matched for age (± 3 years) and gender. The workflow diagram clarifies the design of this case-control study (Fig 1).