Multi method approach to the assessment of data quality in the Finnish Medical Birth Registry.

OBJECTIVE To assess comprehensively the validity of the data in the Finnish Medical Birth Registry (MBR) by the combined use of several controls and internal analysis of the data. DESIGN The MBR data were individually linked to a medical record sample (n = 775) and to all perinatal death certificates in 1987. The data were also compared with annual hospital statistics. The distributions of birth weights and gestational ages were examined. SUBJECTS All stillborn and liveborn babies registered in the MBR in 1987 (n = 59,370). SETTING The nationwide MBR data were compared with medical records from one third of the Finnish hospitals, with statistics for all hospitals, and with nationwide cause of death registry data. MEASUREMENTS AND MAIN RESULTS With regard to most variables, the data quality was good or satisfactory (agreement with medical records 95% or more). Allowing for minor deviations in variables with continuous scales improved the agreement rates further. Explanations could be deduced for items with poor agreement values. For most variables, the amount of missing data was less than 1%. With the exception of caesarean sections, medical procedures were registered in only 30 to 72% of the cases, and the proportion varied strongly between the hospitals. Common diagnoses (32 to 86%) and primary causes of death (59 to 78%) were also poorly recorded. CONCLUSIONS Combined use of several control materials and internal analyses was successful in investigating the whole data content. The data in the MBR were generally valid but diagnoses and most data on medical procedures were not of sufficiently good quality.