title: [Multiple sclerosis in Haute-Garonne: an important underestimation of case numbers].
abstract: BACKGROUND
  In France, the prevalence of multiple sclerosis is estimated between 65 and 125 patients per 100,000 inhabitants with a South-West towards North-East gradient. Nevertheless, the epidemiology of multiple sclerosis remains still imperfectly known, the recent studies being realized, either in a region of France, or from a single data source and thus suscepted not to be exhaustive.
  
  
  OBJECTIVE
  Assessing the prevalence of the multiple sclerosis in 2005 in Haute-Garonne by matching several data sources completed by a capture-recapture method; estimating the exhaustivity of each of the sources.
  
  
  METHODS
  The data sources were hospital data (DRG for the hospitalization, data of consultation), data of public health insurance system (main health insurance, agricultural health insurance, social welfare for self employed), and data from the MIPSEP network. The linkage was based on name, maiden name, first name, date of birth and sex and allowed a first estimation of the number of cases. Models of loglinear regression allowed estimating the total number of case and the sensitivity of each source.
  
  
  RESULTS
  The total number of cases obtained by matching several sources of information amounted to 1549. The use of several data sources increased by 25.6 % the maximum number of patients identified with a single source of information (national health insurance, any insurance). According to the model used, the method of capture-recapture estimated the number of cases up to 1722. Therefore, this study estimated a prevalence of multiple sclerosis between 110 and 149 cases per 100,000 inhabitants in Haute-Garonne.
  
  
  CONCLUSIONS
  The prevalence of the multiple sclerosis is largely underestimated in Haute-Garonne and questions the magnitude over the so-called gradient. Matching several sources of information is indispensable to improve collection of the total number of cases.
authors.affiliation: Département d'information médicale, CHU de Toulouse, Hôtel-Dieu-Saint-Jacques, 2, rue Viguerie, TSA 80035, 31059 Toulouse cedex 9, France. raffy.c@chu-toulouse.fr <raffy.c@chu-toulouse.fr>
authors.forename: C
authors.initials: C
authors.lastname: Sagnes-Raffy
authors.forename: P-A
authors.initials: PA
authors.lastname: Gourraud
authors.forename: V
authors.initials: V
authors.lastname: Hannon
authors.forename: R
authors.initials: R
authors.lastname: Bourrel
authors.forename: M-A
authors.initials: MA
authors.lastname: Laffontan
authors.forename: M-C
authors.initials: MC
authors.lastname: Gaulene
authors.forename: F
authors.initials: F
authors.lastname: Viala
authors.forename: M
authors.initials: M
authors.lastname: Clanet
mesh_terms: D017677:Age Distribution; D015982:Bias; D003625:Data Collection / Q000379:methods*; D005260:Female; D005602:France / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007348:Insurance, Health / Q000706:statistics & numerical data; D016014:Linear Models; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology*; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence; D012111:Residence Characteristics; D012680:Sensitivity and Specificity; D017678:Sex Distribution