Validation of diagnostic codes for Charcot–Marie–Tooth disease in the Danish National Patient Registry

Abstract

Purpose

To validate the diagnostic codes for Charcot–Marie–Tooth disease (CMT) in the Danish National Patient Registry (DNPR) using positive predictive value (PPV) as a measure of validity.

Patients and methods

We used the DNPR to identify all patients diagnosed with at least one primary CMT diagnosis at a specialized department in the Central Denmark Region during the period 1977–2012. From this population, we randomly selected 123 patients for the validation study. Medical files were reviewed and used as reference standard. We estimated the PPV of the CMT diagnoses and stratified the analysis according to age at diagnosis, gender, and calendar time.

Results

In the DNPR, 275 patients were identified. We were able to retrieve 96 medical files from the random sample of 123 patients, and 85 CMT diagnoses were confirmed. The average age at diagnosis was 42.5 years, and 34% were female. The PPV was 88.5% (95% confidence interval: 80.4–94.1).

Conclusion

The CMT diagnoses in the DNPR have high validity. The DNPR can be used as a data source for epidemiologic research on CMT.

Keywords:

• registries
• positive predictive value
• International Classification of Disease codes
• epidemiology

Acknowledgments

The authors are very grateful to Michael Vaeth from The Department of Public Health, Section for Biostatistics at Aarhus University, for providing technical assistance related to the management of register data, and to Lars Pedersen from The Department of Clinical Epidemiology at Aarhus University Hospital for providing helpful advice regarding epidemiological issues. The authors would like to thank the following for assistance in the retrieval of medical records: Anita Højholt from The Department of Neurology at Aarhus University Hospital, Birgitte Forsom Sandal from The Department of Neurology at Holstebro Regional Hospital West Jutland, Friedrich Emanuel Schlesinger from The Department of Neurology at Viborg Regional Hospital Central Jutland, Hatice Tankisi from The Department of Neurophysiology at Aarhus University Hospital, John Rosendahl Østergaard from The Department of Pediatrics at Aarhus University Hospital, Thomas Helweg Thelle from The Department of Pediatrics at Viborg Regional Hospital Central Jutland, and Lene Vels Pedersen from The Department of Pediatrics at Herning Regional Hospital West Jutland.

Disclosure

The authors report no conflicts of interest in this work.