Positive Predictive Values of Procedure Codes on the Treatment of Non-Muscle Invasive Bladder Cancer in the Danish National Patient Registry

Abstract

Globally non-muscle invasive bladder cancer (NMIBC) is a high-incidence disease. There is a large heterogeneity within NMIBC regarding recurrence-and progression risks, and large-scale studies of treatment patterns and prognoses in an everyday setting could result in NMIBC-subgroup treatment optimization, benefiting both patients and the economy. The Danish national registries provide such an opportunity if the registered procedure codes are valid. Therefore, the aim of the study was to validate the International Classification of Diseases, 10th Edition (ICD-10) codes of NMIBC treatment used in the Danish National Patient Registry (DNPR). Patients and Methods: From the DNPR, we randomly selected 200 NMIBC treatment courses identified by the dates of the course and the codes of transurethral resection of the bladder ((TURB), n = 125), photodynamic diagnosis ((PDD), n = 25), bladder instillation with Bacillus Calmette vaccine ((BCG), n = 25), or bladder instillation with chemotherapy/Mitomycin C ((MMC), n = 25). We used medical record reviews as the reference standard and estimated positive predictive values (PPVs) of all procedure codes and negative predictive values (NPVs) of PDD-and the perioperative single-shot MMC codes. Results: We identified the medical records in 150 (75%) of the 200 treatment courses (149 individual patients).

Use of Bladder-Related Medication in Non-Muscle Invasive Bladder Cancer Patients

“…Created in 1977 and including all information on diagnoses and treatments, the Danish National Patient Registry (DNPR) is internationally considered one of the most comprehensive of its kind [14]. The validity of the coding in the DNPR is generally found to be very high, which also applies to the codes related to NMIBC treatment [15,16]. Since 1994, the International Classification of Diseases, 10th Edition (ICD-10) has been used to classify the diagnoses and procedures in the DNPR.…”