A comprehensive characterisation of patients diagnosed with post-COVID-19 condition in Sweden 16 months after the introduction of the ICD-10 diagnosis code (U09.9): a population-based cohort study

Abstract

Background: The objective of this study was to provide a comprehensive characterisation of patients diagnosed with post-COVID-19 condition (PCC) during the first 16 months of usage of the International Classification of Diseases revision 10 (ICD-10) diagnosis code U09.9 in Sweden.

Methods: We used data from national registers and primary healthcare databases for all adult inhabitants of the two largest regions in Sweden, comprising 4.1 million inhabitants (approximately 40% of the Swedish population). We present the cumulative incidence and incidence rate of PCC overall and among subgroups and describe COVID-19 patients with or without PCC regarding sociodemographic characteristics, comorbidities, subsequent diseases, COVID-19 severity, and virus variants.

Findings: Of all registered COVID-19 cases available for PCC diagnosis (n=506,107), 2.0% (n=10,196) had been diagnosed with PCC using ICD-10 code U09.9 as of 15 February 2022 in the two largest regions in Sweden. The cumulative incidence was higher among women compared to men (2.3% vs 1.6%, p<0.001). The majority of PCC cases (n=7,162, 70.2%) had not been hospitalised for COVID-19. This group was more commonly female (69.9% vs 52.9%, p<0.001), had a tertiary education (51.0% vs 44.1%, p<0.001), and was older (median age difference 5.7 years, p<0.001) compared to non-hospitalised COVID-19 patients without PCC.

Interpretation: This characterisation furthers the understanding of patients diagnosed with PCC and could support policymakers with appropriate societal and healthcare resource allocation.