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A Search for Undiagnosed Charcot-Marie-Tooth Disease Among Patients Registered with Unspecified Polyneuropathy in the Danish National Patient Registry

Authors Vaeth S, Andersen H, Christensen R, Jensen UB

Received 18 November 2020

Accepted for publication 9 January 2021

Published 16 February 2021 Volume 2021:13 Pages 113—120


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 4

Editor who approved publication: Professor Henrik Toft Sørensen

Signe Vaeth,1 Henning Andersen,2 Rikke Christensen,1 Uffe Birk Jensen1

1Department of Clinical Genetics, Aarhus University Hospital, Aarhus N, Denmark; 2Department of Neurology, Aarhus University Hospital, Aarhus C, Denmark

Correspondence: Signe Vaeth
Department of Clinical Genetics, Aarhus University Hospital, Brendstrupgaardsvej 21 C, Skejby, Aarhus N, DK-8200, Denmark
Tel + 45 78455510
Fax +45 86783181

Purpose: In a recent study based on data from the Danish National Patients Registry (DNPR), we reported the prevalence of Charcot-Marie-Tooth disease (CMT) in Denmark to be 22.5 per 100.000. This prevalence is most likely a minimum estimate, as many cases of CMT may be misdiagnosed or remain undiagnosed due to the heterogeneous nature of the disorder. The aim of this study was to investigate the possible number of undiagnosed CMT cases among patients registered with unspecified polyneuropathy (UP) diagnoses in the DNPR.
Patients and Methods: From the DNPR we extracted data on all patients given an UP diagnosis in the period 1977 to 2012. We selected all patients diagnosed with a primary UP diagnosis before age 40 at a department of neurology, neurophysiology, clinical genetics or pediatrics, and excluded all patients with a specified polyneuropathy diagnosis or with diagnostic codes related to alcohol and diabetes mellitus. To assess the proportion of possible CMT patients, we performed medical record review in a random sample of patients diagnosed in the Central Denmark Region. To further investigate the possible overlap between UP and CMT in the DNPR, we performed a series of searches for ICD-8 and ICD-10 codes related to CMT.
Results: Between 1977 and 2012, 30.903 patients were diagnosed with UP without also being diagnosed with CMT. A total of 940 patients fulfilled the selection criteria. We found that 21.5% (95% CI 13.1%– 32.2%) of the cases in the random sample fulfilled our criteria for CMT. This estimate increases the prevalence of CMT in Denmark with 3.6 per 100,000 (95% CI 2.4%– 5.5%).
Conclusion: This study illustrates how hitherto undiagnosed CMT patients may be identified in the DNPR and further reports the number of possible CMT cases. Our results support the hypothesis that the true prevalence of CMT is higher than recently reported.

Keywords: registries, International Classification of Disease codes, epidemiology, hereditary neuropathy

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