Increasing Incidence and Prevalence of Pathologic Hemoglobinopathies Among Children in Ontario, Canada from 1991-2013

Abstract

Background: In Ontario, Canada's largest province, population-based health administrative data represents an accessible and useful tool for population surveillance of people with chronic diseases. While hemoglobinopathies can be identified using data from universal hemoglobinopathy screening, which was implemented in November 2006, these data would not contain information on affected immigrants (21.9% of the population). We validated algorithms using provincial health administrative data and newborn screening data to identify children with hemoglobinopathies whether or not they were born in Ontario, thereby creating a population-based surveillance cohort. Objectives: (1) Validate algorithms to identify children with sickle cell disease, thalassemia and other hemoglobinopathies from within health administrative data; and (2) Determine incidence and prevalence of hemoglobinopathies in Ontario children. Methods: For the validation study, a positive reference cohort was established using lists of known hemoglobinopathy patients who were followed at five pediatric hemoglobinopathy treatment sites in Ontario and born between November 24, 2006 and March 31, 2013. Health card numbers of these patients were linked deterministically to unique identification numbers in administrative data, which included data on hospitalizations, physician claims, sociodemographic characteristics, immigration records and cause of death. The negative reference cohort included all children residing in Ontario cities who had never been seen at a hemoglobinopathy centre, and therefore assumed not to have disease. Various combinations of administrative data codes were tested for their ability to identify children <18 years of age with hemoglobinopathies from within the databases, and we selected the algorithms with the highest positive predictive value, while maintaining sensitivity >80%. Using two validated algorithms, we identified all children with hemoglobinopathies born between April 1, 1991 and March 31, 2013. We described the crude incidence and prevalence per 100,000 patient-years (PYs). Results: Two algorithms functioned best to identify incident and prevalent hemoglobinopathy cases (see Table). Among children born between April 1, 1991 to March 31, 2013, 1526 incident hemoglobinopathy patients were identified using Algorithm 1 (crude incidence of 4.85 per 100,000 PYs) and 1660 new hemoglobinopathy patients were identified using Algorithm 2 (crude incidence 5.28 per 100,000 PYs, 95% CI 3.51 to 3.92). In 2013, the overall prevalence of children <18 years living with hemoglobinopathies was 1215-1325 cases. Conclusion: Through an innovative approach using provincial health administrative, immigration and demographic data, this study identified a rising incidence and prevalence of hemoglobinopathies among Ontario children <18 years of age between April 1, 1991 and March 31, 2013, potentially due to increased immigration rates. These findings could be used to inform health services distribution. This surveillance cohort will be used to understand the impact of immigration status on health care inequality for hemoglobinopathy-related health services delivery, as well as to assess outcomes in this important group of chronic diseases. Disclosures Klaassen: Amgen Inc.: Membership on an entity's Board of Directors or advisory committees; Octapharma AG: Consultancy, Honoraria; Agios Pharmaceuticals Inc.: Consultancy; Novartis: Research Funding; Hoffman-La Roche: Consultancy; Shire: Consultancy; Cangene: Research Funding. Jardine:Pfizer: Other: Advisory board; Bayer: Other: Advisory board; Baxalta: Other: Advisory board.

Epidemiology of clinically significant forms of alpha‐ and beta‐thalassemia: A global map of evidence and gaps

“…HbH disease was 0/100 000 births in 2010 in Greece, 33 and 3/100 000 births in Belgium over the period from 1994 to 2004 46 . In Canada, from 2006 to 2011, the birth prevalence of HbH disease or Hb Bart's hydrops fetalis was <1/100 000 births 47 (Table S3, Figure S1).…”

Sickle cell disease in Ontario, Canada: an epidemiologic profile based on health administrative data

“…However, a study in which a similar methodology was used showed that analysis of Ontario health administrative databases is a reliable method of identifying children with hemoglobinopathy. 8 In addition, we did not require multiple interactions to confirm coding accuracy, and, therefore, our findings may be susceptible to false-positive results (i.e., miscoding sickle cell trait as disease).…”

“…Given the high degree of morbidity and related health care costs associated with a diagnosis of sickle cell disease, an estimated population prevalence with demographic characteristics would be of value in resource allocation planning (i.e., investment in additional comprehensive care programs). Although Simpson and colleagues 8 enumerated the number of children in Ontario, Canada, with pathologic hemoglobinopathy, and a more recent effort has been made to register patients with sickle cell disease in the province of Quebec, Canada, who have been diagnosed with COVID-19, 9 a comprehensive registry of patients with sickle cell disease in any region of Canada is not yet available. The frequency with which affected patients access acute and emergency care, however, provides an opportunity to estimate the number of unique patients in a defined geographic area.…”

Drépanocytose hétérozygote composite SC non diagnostiquée, compliquée de septicémie et de cholestase

“…Aux États-Unis et au Royaume-Uni, l’HbSC représente de 25 % à 30 % des drépanocytoses. Entre 1993 et 2013, l’incidence globale des hémoglobinopathies en Ontario, y compris de l’HbSC, a augmenté en raison de l’immigration en provenance de pays où ces maladies sont plus prévalentes 12 . Plusieurs provinces disposent désormais de programmes de dépistage de routine chez les nouveau-nés, incluant la drépanocytose, mais selon une étude américaine, seulement 16 % des jeunes adultes et des adultes d’âge moyen en faisaient état parmi l’ensemble des patients ayant reçu un diagnostic de trait drépanocytaire lors d’un dépistage à la naissance 13 .…”