A Validation Study of the Canadian Organ Replacement Register

Abstract

Accurate and complete documentation of patient characteristics and comorbidities in renal registers is essential to control bias in the comparison of outcomes across groups of patients or dialysis facilities. The objectives of this study were to assess the quality of data collected in the Canadian Organ Replacement Register (CORR) compared with the patient's medical charts. This cohort study of a representative sample of adult, incident patients registered in CORR in 2005 to 2006 examined the prevalence, sensitivity, specificity, positive and negative predictive values, and κ of comorbid conditions and agreement in coding of patient demographics and primary renal disease between CORR and the patient's medical record. The effect of coding variation on patient survival was evaluated. Medical records on 1125 patients were reviewed. Agreement exceeded 97% for health card number, date of birth, and sex and 71% (range 46.6 to 89.1%) for the primary renal disease. Comorbid conditions were under-reported in CORR. Sensitivities ranged from 0.89 (95% confidence interval 0.80, 0.92) for hypertension to 0.47 (0.38, 0.55) for peripheral vascular disease. Specificity was >0.93 for all comorbidities except hypertension. Hazard ratios for death were similar whether calculated using data from CORR or the medical record. Comorbid conditions are under-reported in CORR; however, the associated risks of mortality were similar whether using the CORR data or the medical record data, suggesting that CORR data can be used in clinical research with minimal concern for bias.