Validation of algorithms using International Classification of Diseases for the identification of herpes zoster episodes requiring hospitalization in Quebec, Canada. Issue 41 (1st October 2021)

• Record Type: Journal Article
• Authors: Capistran, Ève; Morin, Vincent; Marcoux, Dominique; Trudel, Esther; Gagné, Micheline; Proulx, Sandra; Nour Abou Chakra, Claire; Gagnon, Nicolas; Carignan, Alex
• Is Part Of: Vaccine. Volume 39:Issue 41(2021)
• Page Start: 6074
• Page End: 6080
• Publication Date: 2021-10-01
• Subjects: HZ Herpes zoster -- PHN post-herpetic neuralgia -- HZh HZ-related hospitalizations -- PPV positive predictive value -- ICD International Classification of Diseases -- VZV varicella-zoster virus; Herpes zoster -- Hospitalization -- Antivirals -- Retrospective cohort study -- Canada; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2021.08.100
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: This study demonstrated high positive predictive value (PPV) of International Classification of Diseases (ICD) codes when identifying hospitalizations due to herpes zoster (HZh) with primary diagnoses. PPV of secondary diagnoses is lower. Antiviral prescription should be added to ICD codes to identify HZh from administrative databases. PPV of primary diagnosis is excellent, but cannot be used alone to identify HZh, as this method as low sensitivity. Abstract: Objective: We determined secular changes in the incidence of hospitalizations due to herpes zoster (HZh) and assessed the validity of HZ International Classification of Diseases (ICD) code algorithms for identifying HZh in a region of Quebec, Canada. Methods: We performed a validation study as part of a retrospective cohort study of adult HZ patients hospitalized at Centre Hospitalier Universitaire de Sherbrooke during 2000–2017. Cases were identified using ICD codes from an inpatient administrative database. HZ cases identified by ICD-9 (053.xx) and ICD-10 (B02.x) codes were chart-confirmed, and performance characteristics of ICD code algorithms were calculated (positive predictive value [PPV] and sensitivity). Results: Overall, 1314 hospitalizations with HZ diagnosis (HZh) with or without complications were identified during 2000–2017. Among the hospitalizations, 526 (44.4%) were due to active HZ disease or a complication related to a recent or previous HZ episode. These hospitalizations were due to active disease at the time of admission (340/526, 64.6%), HZ that developed during hospitalization (120/526, 22.8%), or a complication directly related to a recent or previous HZ episode (66/526, 12.6%). PPV was significantly higher when HZ was the primary diagnosis (276/310, 89%, 95% confidence interval [CI]: 85–92%) than when HZ was a secondary diagnosis (254/928, 27%, 95% CI: 25–30%) (p < 0.0001), and the PPV of a first secondary diagnosis (84/140, 60.0%, 95% CI: 51.3–68.2%) was higher than that of other secondary diagnoses (203/794, 25.6%, 95% CI: 22.6–28.8%) (p < 0.0001). An algorithm combining ICD codes and antiviral usage demonstrated the best sensitivity (86.3%, 95% CI: 83.1–89.1%) and PPV to identify HZh (100%, 95% CI: 99.2–100%). Poisson regression revealed no significant changes in HZh over time (incidence rate ratio: 0.98, 95% CI: 0.92–1.04%; p = 0.5). Conclusion: HZh incidence was stable over time. Prescription of antivirals might be a useful addition to ICD codes to identify HZh cases from administrative databases.