title: Relative versus absolute risk of comorbidities in patients with psoriasis.
abstract: BACKGROUND
  Psoriasis is associated with numerous comorbidities, often reported in terms of relative risk. Both doctors and the general population tend to overestimate the effects of exposures when presented in relative terms, leading to anxiety and potentially poor treatment decisions. Absolute risks might provide a better basis for risk assessment.
  
  
  OBJECTIVE
  To characterize and compare relative and absolute risks of comorbidities in patients with psoriasis.
  
  
  METHODS
  A systematic review using Medline identified comorbidities associated with psoriasis, their relative risks, and information for calculating absolute risks.
  
  
  RESULTS
  The comorbidities associated with psoriasis with the highest relative risk were nonmelanoma skin cancer, melanoma, and lymphoma, with relative risks of 7.5, 6.12, and 3.61, respectively; the attributable risk for these 3 conditions were 0.64, 0.05, and 0.17 per 1000 person-years, respectively. To attribute 1 event of these conditions to psoriasis would require seeing 1551; 20,135; and 5823 patients, respectively.
  
  
  CONCLUSIONS
  Database studies might not fully account for confounders, resulting in overestimates of the risk impact of comorbidities.
  
  
  CONCLUSIONS
  Presenting attributable risk in the form of the number needed to harm provides a clearer picture of the magnitude of risk and a basis for wiser medical decision making and patient education.
authors.affiliation: Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, North Carolina. Electronic address: msaleem@g.clemson.edu.
authors.forename: Mohammed D
authors.initials: MD
authors.lastname: Saleem
authors.affiliation: Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Chelsea
authors.initials: C
authors.lastname: Kesty
authors.affiliation: Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, North Carolina; Department of Pathology, Wake Forest School of Medicine, Winston-Salem, North Carolina; Department of Public Health Science, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Feldman
mesh_terms: D002318:Cardiovascular Diseases / Q000453:epidemiology*; D015897:Comorbidity; D006801:Humans; D015994:Incidence; D008223:Lymphoma / Q000453:epidemiology*; D011565:Psoriasis / Q000453:epidemiology*; D012306:Risk; D018570:Risk Assessment; D012878:Skin Neoplasms / Q000453:epidemiology*
keywords: attributed risk; excess risk; measurements; perception; systematic review