Positive Predictive Value of the ICD-10 Diagnosis Code for Long-COVID

Abstract

To examine the positive predictive value (PPV) of International Classification version 10 (ICD-10) diagnosis codes for long coronavirus disease 2019 (long-COVID) in a Danish Health registry. Patients and Methods: This was a medical record review of all patients with a diagnosis code of long-COVID (DB948A) at all hospitals in the North Denmark Region from February 27, 2020 through June 30, 2021. Confirmed long-COVID was categorized as fulfillment of all three criteria: (1) a positive polymerase chain reaction (PCR) test for SARS-CoV-2 on a respiratory sample or a positive serum antibody test, (2) symptoms suggestive of long-COVID with no other diagnosis considered more likely, and (3) symptom duration >6 weeks.Results: A total of 306 patients were assigned a hospital diagnosis code for long-COVID corresponding to 1.4% of all SARS-CoV-2 positive individuals during the study period (n=21,727). Next, 40 patients were excluded due to incomplete diagnostic evaluation at time of record review leaving 266 patients for analysis. The patients had a median age of 51 years (interquartile range 43-60) and 175/ 266 (66%) were females. Long-COVID was confirmed in 249/266 yielding an overall PPV of 94% (95%CI: 90-96) and did not differ substantially according to most age groups, sex, previous hospitalization for COVID-19, or by using 12 weeks of symptom duration as cut-off. The PPV was low for children and adolescents (n=5), the very elderly (n=9), and those included by secondary long-COVID diagnoses (n=10). Conclusion:The overall PPV of diagnosis codes for long-COVID in the North Denmark Region was high and was likely suitable for future registry-based studies of long-COVID. Caution is advised at the extremes of age and secondary diagnosis codes.

Risk of new‐onset psychiatric sequelae of COVID‐19 in the early and late post‐acute phase

“…Our study did not focus specifically on long COVID, but instead investigated a cohort of patients following a diagnosis of acute COVID-19. It is difficult to know what proportion of these patients went on to develop long COVID; the recent introduction of ICD-10 codes for long COVID 9 may enable studies on this topic in the future.…”

Generalizable Long COVID Subtypes: Findings from the NIH N3C and RECOVER Programs

“…Also, since the use of the code began only recently, patients with long COVID that were diagnosed prior to the introduction of the code are not included, limiting our ability to compare the current clinical manifestations with those observed earlier in the pandemic before widespread vaccination and with different distributions of SARS-CoV2 strains and variants. However, in a pilot study in Denmark, coding with U09.9 was found to have a positive predictive value of 94% for long COVID (56) .…”

“…However, in a pilot study in Denmark, coding with U09.9 was found to have a positive predictive value of 94% for long COVID. 56 Our ability to capture clinical manifestations of long COVID is limited by the accessibility of clinical data in EHR systems. Of the 287 HPO terms we identified as being used in published cohort studies on long COVID, 19 only 116 were identified in our data.…”

A New Look on Long-COVID Effects: The Functional Brain Fog Syndrome

“…In this perspective, brain fog would be one of the symptoms of this broader syndrome, best for cognitive aspects. On the other hand, several studies treat fatigue and brain fog as distinct post-infection sequelae, although frequently occurring together [ 2 , 13 , 25 , 26 ]. The former would involve mainly a sort of physical asthenia, while the latter would be characterized primarily by an excessive easiness to cognitive weakness.…”

“…In these studies, brain fog and forms of cognitive impairment would substantially overlap [ 4 , 6 , 14 , 17 , 23 ]. On the other hand, several studies keep brain fog, and cognitive deficits separate, suggesting that they represent two distinct clinical entities [ 7 , 9 , 10 , 13 , 16 , 26 , 28 , 29 ]. Despite this, data on their co-occurrence are lacking.…”