title: [Are drugs taken as prescribed?].
abstract: BACKGROUND
  The term "adherence" is used to describe whether drugs are taken as prescribed. This article outlines what is known about adherence for several central drug classes, which factors modify adherence, the consequences of low adherence and how adherence can be improved.
  
  
  METHODS
  We reviewed a selection of studies of adherence for the following seven drug classes: antidiabetics, antiepileptics, antihypertensives, statins, psychotropic drugs, antibiotics and analgesics.
  
  
  RESULTS
  For antidiabetics, the proportion of patients with high adherence varied between 31 % and 80 % in the different studies. The corresponding figures for the other drug classes were: antiepileptics, 61-74 %; antihypertensives, 23-73 %; statins, 25-44 %; psychotropic drugs, 21-80 %; antibiotics, 41-70 % and analgesics, 41-53 %. As a general rule, adherence declined with time. For serious diseases, a decline in adherence led to a worsening of symptoms and an increased risk of hospitalisation and death. Dosing once daily proved to result in higher adherence than multiple daily dosing. Complex therapy regimes, depression, impaired cognitive function, side effects and inadequate follow-up reduce adherence.
  
  
  CONCLUSIONS
  It is important to achieve high adherence, not least for serious diseases. In order to improve adherence it is necessary to identify patients who have low adherence, understand why the patient does not take the drugs and whether there are any practical problems related to intake. Good communication between patient and doctor is a key factor.
authors.affiliation: Institutt for laboratoriemedisin barne- og kvinnesykdommer, Norges teknisk-naturvitenskapelige universitet, og Avdeling for klinisk farmakologi, St. Olavs hospital, Norway.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Hov
authors.forename: Margunn
authors.initials: M
authors.lastname: Bjartnes
authors.forename: Lars
authors.initials: L
authors.lastname: Slørdal
authors.forename: Olav
authors.initials: O
authors.lastname: Spigset
mesh_terms: D000700:Analgesics / Q000008:administration & dosage; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D000927:Anticonvulsants / Q000008:administration & dosage; D000959:Antihypertensive Agents / Q000008:administration & dosage; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D055118:Medication Adherence; D004364:Pharmaceutical Preparations / Q000008:administration & dosage*; D010817:Physician-Patient Relations; D011619:Psychotropic Drugs / Q000008:administration & dosage
chemical_list: D000700:Analgesics; D000900:Anti-Bacterial Agents; D000927:Anticonvulsants; D000959:Antihypertensive Agents; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007004:Hypoglycemic Agents; D004364:Pharmaceutical Preparations; D011619:Psychotropic Drugs