2.2 Data extraction and quality assessment
Information was carefully extracted from all eligible publications by two independent authors, including author’s name publication date, country, sample size, plasma concentration and adjusted serum concentration of CDRCBZ, CDRCBZE and CDRCBZD, CDRCBZE : CDRCBZ and CDRCBZD : CDRCBZE ratios, genotypes distribution, drug resistant patients (defined as no change or less than 50% reduction in seizure frequency for at least 1 year during treatment with CBZ and drug responsive patients defined as seizure-free or a 50% or greater reduction in seizure frequency for at least 1 year during treatment with CBZ) [8, 19]. If diverse results were generated the disagreement was resolved by discussion between the two authors or by asking a third investigator. The authors of the studies were contacted for additional data when necessary and applicable.