Agreement of label information of cardiovascular drugs in pregnancy among Korea, the USA, the UK, and Japan

- We compare label information of cardiovascular drugs used during pregnancy.
- Evidence and recommendation level are evaluated to see the similarities of labels.
- Label information differ widely among four countries; Korea, USA, UK, and Japan.
- Korea and Japan are more conservative in pregnancy warnings than USA and UK.
- Standardization and regular updates are needed for more reliable safety information.

Drug label is a common source of information; however, the content varies widely. This study aims to evaluate label information on cardiovascular drugs regarding pregnancy for their similarities in Korea, USA, UK, and Japan. Study drugs were selected as following (1) cardiovascular drugs according to the WHO ATC code (C01-C09) and (2) drugs currently marketed in all four countries were included. Evidence level was classified into five categories ('Definite', 'Probable', 'Possible', 'Unlikely', and 'Unclassified') and recommendation level was classified into four categories ('Contraindicated', 'Cautious', 'Compatible', and 'Unclassified'). Frequency and proportion were presented. Percent agreement and kappa coefficient with 95% confidence interval (CI) were calculated using SAS ver. 9.3. Total of 50 cardiovascular drugs were included. 'Unclassified' was represented the most in Korea, followed by Japan and UK (58%, 54%, and 46%, p < 0.05). For recommendation level, the majority of drugs in all four countries were classified as 'contraindicated' or 'cautious'. Japanese labels had the largest proportion of 'contraindicated' level (62%), and Korea and UK followed (58%, 44%, p < 0.05). Only in the USA, 10.0% of the drugs were 'compatible' whereas, there were none in Korea, UK, and Japan (p < 0.01). Korea and Japan showed a substantial agreement in evidence and recommendation level (kappa = 0.69, 0.67). Labels of cardiovascular drugs in pregnancy differed widely. Reliable safety information in pregnancy should be provided through regular updates.