title: Representativeness of diabetes patients participating in a web-based adverse drug reaction monitoring system.
abstract: OBJECTIVE
  Lareb Intensive Monitoring, LIM, is a non-interventional observational cohort method which follows first-time users of certain drugs during a certain period of time and collects information about adverse drug reactions, ADRs. In order for LIM to be a useful pharmacovigilance tool, it is important to know whether the LIM population is comparable to the whole population using the drug. The aim of this study is to compare the LIM diabetes population with an external diabetes reference population on characteristics that may influence the patient's susceptibility for ADRs.
  
  
  METHODS
  In this study, a LIM diabetes population was compared to a reference diabetes population derived from The Groningen Initiative to ANalyse Type 2 diabetes Treatment project. Comparisons were made regarding age, gender, body mass index and polypharmacy, as well as diabetes medication used and disease/treatment duration.
  
  
  RESULTS
  LIM patients were more often men (58.5% vs 50.8%) and in general younger (59.1 vs 64.7 years) and healthier, by that meaning they had a higher percentage of de novo treated patients (55.5% vs 53.2%), a shorter diabetes treatment duration (3.7 vs 5.5 years) and used less co-medication than patients in the reference population.
  
  
  CONCLUSIONS
  This study shows that diabetes patients participating in a web-based intensive monitoring system differ from a reference population. The observed differences might lead to an underestimation of ADRs, but it is not clear whether this would also influence the type or time-course of the reported ADRs. When interpreting results from LIM studies, one should take these differences into account.
authors.affiliation: Netherlands Pharmacovigilance Centre Lareb, 's-Hertogenbosch, The Netherlands. l.harmark@lareb.nl
authors.forename: Linda
authors.initials: L
authors.lastname: Härmark
authors.forename: Susanne
authors.initials: S
authors.lastname: Alberts
authors.forename: Eugène
authors.initials: E
authors.lastname: van Puijenbroek
authors.forename: Petra
authors.initials: P
authors.lastname: Denig
authors.forename: Kees
authors.initials: K
authors.lastname: van Grootheest
mesh_terms: D016907:Adverse Drug Reaction Reporting Systems; D000368:Aged; D016009:Chi-Square Distribution; D015897:Comorbidity; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects*; D020407:Internet; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D060735:Pharmacovigilance; D019338:Polypharmacy; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D007004:Hypoglycemic Agents