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The Incidence and Prevalence of Multiple Sclerosis in Nova Scotia, Canada

  • Ruth Ann Marrie (a1), John D. Fisk (a2) (a3), Karen J. Stadnyk (a4), Bo Nancy Yu (a1), Helen Tremlett (a5), Christina Wolfson (a6), Sharon Warren (a7), Virender Bhan (a3) and CIHR Team in the Epidemiology and Impact of Comorbidity on Multiple Sclerosis...

Abstract

Background:

Estimates of incidence and prevalence are needed to determine disease risk and to plan for health service needs. Although the province of Nova Scotia, Canada is located in a region considered to have a high prevalence of multiple sclerosis (MS), epidemiologic data are limited.

Objective:

We aimed to validate an administrative case definition for MS and to use this to estimate the incidence and prevalence of MS in Nova Scotia.

Methods:

We used provincial administrative claims data to identify persons with MS. We validated administrative case definitions using the clinical database of the province's only MS Clinic; agreement between data sources was expressed using a kappa statistic. We then applied these definitions to estimate the incidence and prevalence of MS from 1990 to 2010.

Results:

We selected the case definition using ≥7 hospital or physician claims when >3 years of data were available, and ≥3 claims where less data were available. Agreement between data sources was moderate (kappa = 0.56), while the positive predictive value was high (89%). In 2010, the age-standardized prevalence of MS per 100,000 population was 266.9 (95% CI: 257.1- 277.1) and incidence was 5.17 (95% CI: 3.78-6.56) per 100,000 persons/year. From 1990-2010 the prevalence of MS rose steadily but incidence remained stable.

Conclusions:

Administrative data provide a valid and readily available means of estimating MS incidence and prevalence. MS prevalence in Nova Scotia is among the highest in the world, similar to recent prevalence estimates elsewhere in Canada.

RÉSUMÉ Contexte:

Des estimés de l'incidence et de la prévalence sont nécessaires pour établir le risque d'une maladie et pour la planification des services de santé. Bien que la province de Nouvelle-Écosse au Canada soit située dans une région considérée comme à haute prévalence de sclérose en plaques (SP), il existe peu de données épidémiologiques à ce sujet.

Objectif:

Le but de l'étude était de valider une définition administrative de cas pour la SP et de l'utiliser pour estimer l'incidence et la prévalence de la SP en Nouvelle-Écosse.

Méthode:

nous avons utilisé des données administratives provinciales de réclamation pour identifier les individus atteints de la SP. Nous avons validé les définitions administratives de cas au moyen de la base de données cliniques de la seule clinique de SP de cette province. La concordance entre les sources de données a été évaluée au moyen du test de concordance Kappa. Nous avons ensuite appliqué ces définitions pour estimer l'incidence et la prévalence de la SP de 1990 à 2010.

Résultats:

Nous avons choisi la définition de cas au moyen de 7 réclamations ou plus provenant d'un hôpital ou d'un médecin quand des données couvrant une période de plus de 3 ans étaient disponibles et 3 réclamations ou plus quand moins de données étaient disponibles. La concordance entre les sources de données était modérée (kappa = 0,56) et la valeur prédictive positive était élevée (89%). En 2010, la prévalence de la SP ajustée pour l'âge par 100 000 de population était de 266,9 (IC à 95% : 257,1 à 177,1) et l'incidence était de 5,17 (IC à 95% : 3,78 à 6,56) par 100 000 de population par année. De 1990 à 2010, la prévalence de la SP a augmenté régulièrement mais son incidence est demeurée stable.

Conclusions:

Les données administratives fournissent des moyens valides et facilement disponibles d'estimer l'incidence et la prévalence de la SP. La prévalence de la SP en Nouvelle-Écosse est l'une des plus élevées dans le monde et elle est comparable à celle des autres régions du Canada.

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Copyright

Corresponding author

Health Sciences Center, GF-533, 820 Sherbrook Street, Winnipeg, Manitoba, R3A 1R9, Canada. Email: rmarrie@hsc.mb.ca.

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