title: Prevalence of patients using drugs metabolized by cytochrome P450 2D6 in different populations: a cross-sectional study.
abstract: BACKGROUND
  Despite a large number of studies investigating the potential clinical relevance of CYP2D6 genotyping in preventing treatment failure (eg, insufficient efficacy and/or unacceptable adverse effects), the prevalence of patients using drugs metabolized by that isoenzyme is relatively unknown.
  
  
  OBJECTIVE
  To investigate the prevalence of patients in different populations using drugs metabolized by CYP2D6.
  
  
  METHODS
  In this cross-sectional study, 6 different patient populations were investigated: general, general hospital, geriatric, psychogeriatric, psychiatric, and mentally retarded. From every population, 150 adults using at least one drug were randomly selected. Primary outcome was the prevalence of patients using at least one drug metabolized by CYP2D6. The prevalence of patients using at least one CYP2D6 substrate in different populations was compared with the general population using chi(2) statistics. Data were expressed as a relative risk with a 95% confidence interval.
  
  
  RESULTS
  Patients from the general hospital (RR 1.81; 95% CI 1.26 to 2.62), geriatric patients (RR 2.16; 95% CI 1.26 to 2.62), psychogeriatric patients (RR 2.31; 95% CI 1.63 to 3.27), and psychiatric patients (RR 2.44; 95% CI 1.73 to 3.44) were treated more frequently with at least one drug metabolized by CYP2D6 compared with patients in the general population. Approximately 50% of psychiatric (52%), psychogeriatric (49%), and geriatric (46%) patients used at least one drug metabolized by CYP2D6. In total, 416 drugs metabolized by CYP2D6 were prescribed, with 257 (62%) of these classified as an antidepressant (Anatomical and Therapeutic Chemical [ATC] category N06A) or antipsychotic (ATC N05A).
  
  
  CONCLUSIONS
  Several patient populations (eg, psychiatric, psychogeriatric, geriatric) have a high prevalence of patients treated with at least one drug metabolized by CYP2D6. This study does not provide evidence regarding the clinical evidence of CYP2D6 genotyping, but shows that, if CYP2D6 genotyping is relevant for patient care, the highest probability of cost-effectiveness will, most likely, be in specific populations.
authors.affiliation: Faculty of Science, Division of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Mulder
authors.forename: Eibert R
authors.initials: ER
authors.lastname: Heerdink
authors.forename: Elsje E
authors.initials: EE
authors.lastname: van Iersel
authors.forename: Frederik W
authors.initials: FW
authors.lastname: Wilmink
authors.forename: Antoine C G
authors.initials: AC
authors.lastname: Egberts
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000928:Antidepressive Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D014150:Antipsychotic Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics* / Q000378:metabolism*; D003863:Depression / Q000188:drug therapy / Q000378:metabolism; D004363:Drug Utilization / Q000706:statistics & numerical data*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000188:drug therapy / Q000378:metabolism; D008875:Middle Aged; D010597:Pharmacogenetics
chemical_list: D000928:Antidepressive Agents; D014150:Antipsychotic Agents; D019389:Cytochrome P-450 CYP2D6