Phase 1: Conversion of source data to OMOP-CDM
The source data was mapped onto the OMOP-CDM except for the “Procedures” and “Death” tables, which were absent in the source dataset. Table 1 shows the quantity of data imported and a comparison with source data tables. More than 90% of records from the original table were mapped over to the CDM, except for “Drug Exposure”, as dispensing records included many non-drug items such as foods, syringes and gauzes. Other types of records not mapped to the CDM included persons with no information on birth date, and laboratory records where the corresponding LOINC codes were unavailable and with few records. Diagnoses involving condition occurrences such as road accidents were excluded as these were non-crucial for pharmacovigilance studies. Records of 245,561 unique patients were converted into the OMOP-CDM.