title: Longitudinal monitoring of the safety of drugs by using a web-based system: the case of pregabalin.
abstract: OBJECTIVE
  Information about the time course of adverse drug reactions (ADRs) is often lacking. If this information would be available, it could help increase patient's adherence to drugs when experiencing an ADR. The aim of this study was to demonstrate how a web-based intensive monitoring system using the patient as a source of information can be used to gather longitudinal safety data of a drug. In this study, pregabalin was used as an example.
  
  
  METHODS
  First-time users of pregabalin were approached in Dutch pharmacies between 1 August 2006 and 31 January 2008. After online registration, patients received questionnaires by email 2 weeks, 6 weeks, 3 months and 6 months after the start of the drug use. Data on patient characteristics, drug use and ADRs were collected and analysed.
  
  
  RESULTS
  A total of 1373 patients registered for the pregabalin study. Of these patients, 1051 (76.5%) filled in at least one questionnaire. On an aggregated level, the ADR profile remained relatively stable over time. Incidence densities showed that the five most frequently reported reactions occurred early in the treatment. Initially, the majority of the patients did not undertake any action when experiencing an ADR. Recovery did not seem to be completely dependent of drug cessation.
  
  
  CONCLUSIONS
  With web-based intensive monitoring, it is possible to study the time course of ADRs. This method can be a valuable addition to pharmacovigilance because it can generate other types of information as compared with spontaneous reporting and other intensive monitoring methodologies.
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: Eugene
authors.initials: E
authors.lastname: Puijenbroek
authors.forename: Kees
authors.initials: K
authors.lastname: Grootheest
mesh_terms: D000293:Adolescent; D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems / Q000706:statistics & numerical data*; D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000009:adverse effects*; D002648:Child; D003625:Data Collection / Q000379:methods; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D020407:Internet; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D000069583:Pregabalin; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D000927:Anticonvulsants; D000069583:Pregabalin; D005680:gamma-Aminobutyric Acid