Medical complications in patients with stroke: data validity in a stroke registry and a hospital discharge registry

BACKGROUND Stroke patients frequently experience medical complications; yet, data on incidence, causes, and consequences are sparse. OBJECTIVE To examine the data validity of medical complications among patients with stroke in a population-based clinical registry and a hospital discharge registry. METHODS We examined the predictive values, sensitivity and specificity of medical complications among patients admitted to specialized stroke units and registered in the Danish National Indicator Project (DNIP) and the Danish National Registry of Patients (NRP) between January 2003 and December 2006 (n = 8,024). We retrieved and reviewed medical records from a random sample of patients (n = 589, 7.3%). RESULTS We found substantial variation in the data quality of stroke-related medical complication diagnoses both within the specific complications and between the registries. The positive predictive values ranged from 39.0%-87.1% in the DNIP, and from 0.0%-92.9% in the NRP. The negative predictive values ranged from 71.6%-98.9% in the DNIP and from 63.3% to 97.4% in the NRP. In both registries the specificity of the diagnoses was high. The sensitivity ranged from 23.5% (95% confidence interval [CI]: 14.9-35.4) for falls to 62.9% (95% CI: 54.9-70.4) for urinary infection in the DNIP, and from 0.0 (95% CI: 0.0-4.99) for falls to 18.1% (95% CI: 2.3-51.8) for pressure ulcer in the NRP. CONCLUSION The DNIP may be useful for studying medical complications among patients with stroke.