Background: Obstetric outcome data can be accessed by a variety of different methods in New South Wales, Australia, including Diagnosis-Related Group (DRG) summaries and the Midwives Data Collection (MDC). The accuracy of the reporting of the obstetric complications encompassed by the hypertensive disorders of pregnancy (HDP) has been doubted owing to the inconsistency and confusing coding categories available in both coding systems.
Aim: To test that there would be no disagreement in coding between DRG coding, MDC coding and a disorder-specific database.
Methods: A prospective disorder-specific database, namely the Hypertensive Disorders of Pregnancy Database (HDPDB), was maintained for 6 months and diagnoses were compared with the DRG and MDC coding systems. Medical records of all women (n = 230) who received a HDP coding during this period were examined and recoded using the Australasian Society for the Study of Hypertension in Pregnancy diagnostic groupings. The HDPDB was the gold standard for the comparison of coding.
Results: Significant coding errors were found in both systems available. Sixty-four percent (P < 0.001) of medical records were incorrectly coded in the DRG coding system and 56% (P < 0.001) were incorrectly coded in the MDC.
Conclusions: Current database systems are unreliable for recording maternal medical conditions, such as hypertension, and accuracy can only be assured with the use of a disorder-specific database, such as the HDPDB.