title: Increased overall drug utilization in patients with psoriasis: a case-control study based on Dutch general practitioner data.
abstract: BACKGROUND
  Medication use in patients with psoriasis has been studied mostly in the context of psoriasis comorbidities.
  
  
  OBJECTIVE
  To investigate detailed drug utilization in patients with psoriasis compared with controls in a population-based sample.
  
  
  METHODS
  This was a case-control study based on drug prescriptions derived from a Dutch general practitioner database where patients with psoriasis and controls without psoriasis were matched 1 : 1 for age, sex, general practitioner and duration of follow-up, between 2002 and 2012. We calculated Mantel-Haenszel odds ratios (ORs) and 95% confidence intervals (CIs) for all therapeutic groups and chemical substances.
  
  
  RESULTS
  In total 17 627 patients with psoriasis and 17 627 controls were followed for > 4 years. Overall 20% of patients with psoriasis received no psoriasis treatment and 8% had moderate-to-severe disease. During the entire follow-up a mean of nine unique drugs were prescribed in patients with psoriasis; this was significantly higher than in controls (mean of seven). Drug use did not peak around the date of diagnosis for psoriasis, but remained constant over time. All of the most commonly prescribed therapeutic groups were significantly more often prescribed in patients with psoriasis than in controls. These included drugs associated with psoriasis symptoms and treatment (OR 2·17, 95% CI 2·07-2·28 and OR 22, 95% CI 21-25, respectively), drugs related to psoriasis comorbidities (1·46, 95% CI 1·39-1·53) and a proportion of drugs that were a priori not expected to be increased in patients with psoriasis, such as nasal preparations and laxatives.
  
  
  CONCLUSIONS
  Patients with psoriasis received more prescriptions for all drugs, regardless of associated comorbidities. This overall increased use of drugs suggests an increased healthcare utilization in patients with psoriasis identified in routine databases.
authors.affiliation: Department of Dermatology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: E A
authors.initials: EA
authors.lastname: Dowlatshahi
authors.affiliation: Department of Dermatology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: L M
authors.initials: LM
authors.lastname: Hollestein
authors.affiliation: PHARMO Institute for Drug Outcomes Research, Utrecht, the Netherlands.
authors.forename: R M C
authors.initials: RM
authors.lastname: Herings
authors.affiliation: Department of Dermatology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Nijsten
authors.affiliation: Department of Dermatology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Wakkee
mesh_terms: D016022:Case-Control Studies; D002908:Chronic Disease; D003879:Dermatologic Agents / Q000627:therapeutic use*; D004363:Drug Utilization / Q000706:statistics & numerical data; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011565:Psoriasis / Q000188:drug therapy* / Q000453:epidemiology
chemical_list: D003879:Dermatologic Agents