Underreporting of external cause codes in the Finnish Hospital Discharge Register

Abstract

Hospital discharge data (HDD) represent one of the most valuable information sources for injury prevention and control. To investigate external code of injury (E-code) underreporting in the Finnish National Hospital Discharge Register from 1 January 1987 to 31 December 2004. HDD for discharges with an injury as the main diagnosis were extracted from the FNHDR. The selection was made using codes for nature of injury (1987-1995, ICD-9; 1996-2004, ICD-10). The proportion of injury discharges with a missing E-code was examined by sex, age, hospital districts, type of hospital, duration of hospitalization, and nature of injury. In 432,549 (23.1%) of the recorded 1,868,519 discharges, an E-code was missing. The proportion of the discharges with a missing E-code varied among the above variables. During the period 1987-2004, the overall E-code underreporting decreased from 18.0% to 12.8%. The introduction of the ICD-10 in 1996 was followed by a dramatic increase (up to 57.5% of all discharges) in E-code underreporting. More attention ought to be dedicated to teaching and periodic training on the use of E-codes. Educational activities should specifically target the medical doctors, who, in Finland, are responsible for assigning the E-codes.