The Danish lung cancer registry: A nationwide validation study

This study evaluates the validity of the information in the Danish Lung Cancer Registry (DLCR). Since 2000, the DLCR has been a tool for monitoring interventions and outcome of all Danish lung cancer patients with the intent to streamline and improve treatment and survival. The DLCR receives information from the Danish Patient Registries in addition to clinical information from the treating physicians. In the year 2022, more than 50 papers have been published using DLCR as a data source. However, the DLCR has not previously been validated.

A random sample of 1000 patients diagnosed with non-small cell lung cancer from 2014 to 2016 and recorded in the DLCR were included for validation. Medical records were reviewed and were considered as the "gold standard" to which data listed in the DLCR were compared.

Information was retrieved from medical charts for all patients. Agreement on stage at diagnosis was 90.1 % (95 % CI 88.0-91.9) and on date of diagnoses was 93.8 (95 % CI 92.1-93.2). Agreement on smoking status in pack years (+/- 10 pack years) was 91.2 % (95 % CI 88.6-93.2). The positive predictive value of treatment intent was 87.4 (95 % CI 85.1-89.6).

The data in the DLCR are complete, detailed and accurate. The comparison of data from the DLCR with the medical records revealed overall high validity of the data in the registry.