Developing International Classification of Disease code definitions for the study of enteric infection sequelae in Canada.

Background

Enteric infections and their chronic sequelae are a major cause of disability and death. Despite the increasing use of administrative health data in measuring the burden of chronic diseases in the population, there is a lack of validated International Classification of Disease (ICD) code-based case definitions, particularly in the Canadian context. Our objective was to validate ICD code definitions for sequelae of enteric infections in Canada: acute kidney injury (AKI); hemolytic uremic syndrome (HUS); thrombotic thrombocytopenic purpura (TTP); Guillain-Barré syndrome/Miller-Fisher syndrome (GBS/MFS); chronic inflammatory demyelinating polyneuropathy (CIDP); ankylosing spondylitis (AS); reactive arthritis; anterior uveitis; Crohn's disease, ulcerative colitis, celiac disease, erythema nodosum (EN); neonatal listeriosis (NL); and Graves' disease (GD).

Methods

We used a multi-step approach by conducting a literature review to identify existing validated definitions, a clinician assessment of the validated definitions, a chart review to verify proposed definitions and a final clinician review. We measured the sensitivity and positive predictive value (PPV) of proposed definitions.

Results

Forty studies met inclusion criteria. We identified validated definitions for 12 sequelae; clinicians developed three (EN, NL, GD). We reviewed 181 charts for 6 sequelae (AKI, HUS, TTP, GBS/MFS, CIDP, AS). Sensitivity (42.8%-100%) and PPV (63.6%-100%) of ICD code definitions varied. Six definitions were modified by clinicians following the chart review (AKI, TTP, GBS/MFS, CIDP, AS, reactive arthritis) to reflect coding practices, increase specificity or sensitivity, and address logistical constraints.

Conclusion

The multi-step design to derive ICD code definitions provided flexibility to identify existing definitions, to improve their sensitivity and PPV and adapt them to the Canadian context.

Déclaration de conflit d'intérêts

Competing interests Ethics approval was received from the University of British Columbia Clinical Review Ethics Board (H18-01664). EG and SEM report funding for this study as per the funding statement. At the time of the study, EG’s spouse worked for an electronic medical records’ company; this interest was not related to, or used in, this study. SEM reports other relationships though these interests were not used in this study: she has served as a paid expert on behalf of the Attorney General of Canada in legal proceedings, providing evidence on the public health risks and benefits of unpasteurised milk; she is an expert on the Joint FAO/WHO Expert Meetings on Microbiological Risk Assessment (JEMRA) Roster of Experts; she is a Member of the WHO Foodborne Disease Burden Epidemiology Reference Group. GK reports honoraria for speaking from AbbVie, Janssen, Pfizer, Amgen, Sandoz, and Pendophram; research support from Ferring; shared ownership of a patent: treatment of inflammatory disorders, autoimmune disease, and PBC. UTI Limited Partnership, assignee. Patent WO2019046959A1. PCT/CA2018/051098. 7 Sept. 2018; these interests were not related to, or used in, this study. JC reports research support from Pfizer and UCB for unrelated research; advisory board consulting fees from Abbvie, Organon, UCB, Novartis, Eli Lilly, Sandoz, Jansen, Pfizer, Roche, Merck, Viatris, and Fresenius Kabi; paid lectures from Eli Lilly, Viatris, Abbvie, Pfizer, Novartis, Fresenius Kabi, and UCB; support for attending ACR 2021 meeting from Jansen; unpaid leadership roles at Spondyloarthritis Research Consortium of Canada, Spondyloarthritis Research and Treatment Network, Group for Research and Assessment of Psoriasis and Psoriatic arthritis, and Assessment of Spondyloarthritis International Society; these interests were not related to, or used in, this study. KC reports board membership at CIDP Foundation of Canada, though this interest was not related to this study. All other authors declare no competing interests.