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Concordance Between ICD-10 Codes and Clinical Diagnosis of Hypoparathyroidism in Sweden

Authors Kamal W, Björnsdottir S, Kämpe O, Trolle Lagerros Y

Received 18 December 2019

Accepted for publication 22 February 2020

Published 24 March 2020 Volume 2020:12 Pages 327—331


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 4

Editor who approved publication: Professor Henrik Toft Sørensen

Wafa Kamal,1,2 Sigridur Björnsdottir,1,3 Olle Kämpe,3– 5 Ylva Trolle Lagerros6,7

1Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; 2Department of Medicine, Capio Sankt Görans Hospital, Stockholm, Sweden; 3Department of Endocrinology, Karolinska University Hospital, Stockholm, Sweden; 4Department of Medicine (Solna), Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden; 5K.G. Jebsen Center for Autoimmune Diseases, University of Bergen, Bergen, Norway; 6Clinical Epidemiology Division, Department of Medicine, Karolinska Institutet, Stockholm, Sweden; 7Obesity Center, Academic Specialist Center, Stockholm Health Services, Stockholm, Sweden

Correspondence: Wafa Kamal
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm 171 77, Sweden
Tel +46 858703620

Introduction: Chronic hypoparathyroidism is a rare disorder. The disease is characterized by low serum calcium, high serum phosphate, and deficient production of parathyroid hormone. The most common etiology is unintentional damage and intentional removal to the parathyroid glands during anterior neck surgery. Other causes include genetic disorders and autoimmune diseases. Knowledge about the epidemiology of chronic hypoparathyroidism is sparse and the prevalence in Sweden is unknown. It is of importance to know the validity of the registers used to study the epidemiology of hypoparathyroidism in Sweden.
The purpose of this study was to validate the International Classification of Diseases - 10th revision (ICD-10) diagnosis of hypoparathyroidism in the Swedish National Patient Register.
Methods: We included patients with the ICD-10 diagnosis of hypoparathyroidism that were found in the Swedish National Patient Register during 2004 to 2016. Through the unique national registration number assigned to all Swedish inhabitants, we could link this information to the Swedish Prescribed Drug Register. We included patients with an ICD-10 diagnosis for hypoparathyroidism and on concurrent conventional treatment for the disease. The validation of the diagnosis was assessed through review of medical records of 120 patients.
Results: A total of  958 patients, 70% women (n=671) and 30% men (n=287) met the inclusion criteria. In total, 120 randomly chosen medical records were reviewed and 109 cases were confirmed. This corresponds to an overall positive predictive value of 91%.
Conclusion: The validity of the ICD-10 diagnosis of hypoparathyroidism in the Swedish National Patient Register is high and the register is a reliable source for further research. There is a risk of miscoding when assigning an ICD-code to the medical records. We urge clinicians to be aware of this risk, especially the risk of mix-ups with the more common diagnosis of hyperparathyroidism.

Keywords: hypoparathyroidism, parathyroid glands, validations studies, Sweden, International Classification of Diseases, registers

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