Study design: Retrospective register study enhanced and verified by medical records.
Objectives: To study whether electronic searches of discharge diagnosis are valid for epidemiological research of traumatic spinal cord injury (SCI), using the International Classification of Diseases (ICD).
Settings: Haukeland University Hospital, Bergen, Norway.
Methods: We identified all hospital admissions with discharge codes suggesting a traumatic SCI from ICD-8 to ICD-10 in the electronic database at Haukeland University Hospital, and ascertained the cases by reviewing all hospital records.
Results: 1080 patients had an ICD diagnostic code suggesting a traumatic SCI. Only 260 were verified when reviewing the hospital records. The ICD-10 codes had superior positive predictive values (PPV) and likelihood ratios (LR+) compared with the codes from ICD-8 and ICD-9. Combining seven codes from ICD-10 (S14.0, S14.1, S24.0, S24.1, S34.1, S34.3, T91.3) gave the highest sensitivity (0.83), specificity (0.97), PPV (0.88) and LR+ (30.23).
Conclusion: Obtaining hospital discharge diagnoses solely from electronic databases overestimates the incidence of traumatic SCI. Identification of patients using ICD-10 codes is more complicated because acute traumatic SCI and traumatic SCI sequelae are listed with several codes. The latest ICD version proved to be most reliable when identifying patients with traumatic SCI. However, ICD data cannot be trusted without extensive validity checks for either research or for health planning and administration.