title: Assessing the validity and response distribution of the simplified psoriasis index in patients receiving phototherapy.
abstract: OBJECTIVE
  The simplified psoriasis index (SPI) is a three-part multidimensional tool incorporating disease severity, psychosocial impact and historical course completed by the health-care professional (professional SPI, [proSPI]) or the patient (self-assessment SPI, [saSPI]). We aimed to assess the validity and response distribution of proSPI and saSPI in patients with psoriasis undergoing phototherapy.
  
  
  METHODS
  The validity and response distribution of SPI was assessed by recording saSPI and proSPI in patients with psoriasis before and after a course of phototherapy. Recruitment ended once 100 complete data sets were available for analysis.
  
  
  RESULTS
  Altogether 52 of the 100 patients evaluated were male and most (93) underwent narrowband UVB phototherapy. There was a close correlation between the proSPI-current severity score (proSPI-s) with the psoriasis area and severity index (PASI) score (r = 0.76, r = 0.86) before and after treatment, respectively. Although pretreatment correlation between the saSPI-current severity score (saSPI-s) and PASI was weak (r = 0.39), a more close correlation was noted at the end of treatment (r = 0.50). A moderate correlation was observed between the SPI-psychosocial impact score (SPI-p) and the dermatology life quality index (DLQI), both before and after phototherapy (r = 0.64, r = 0.73). The SPI had wide response distributions in all three domains.
  
  
  CONCLUSIONS
  Both versions of SPI demonstrated wide response distributions and the proSPI-s in particular was shown to have good validity with PASI.
authors.affiliation: Department of Dermatology, Royal Liverpool and Broadgreen University Hospitals, Liverpool, UK.
authors.forename: Nekma
authors.initials: N
authors.lastname: Meah
authors.affiliation: Department of Dermatology, Royal Liverpool and Broadgreen University Hospitals, Liverpool, UK.
authors.forename: Ali
authors.initials: A
authors.lastname: Alsharqi
authors.affiliation: Department of Dermatology, Royal Liverpool and Broadgreen University Hospitals, Liverpool, UK.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Azurdia
authors.affiliation: Department of Dermatology, Royal Liverpool and Broadgreen University Hospitals, Liverpool, UK.
authors.forename: Lynne-Catherine
authors.initials: LC
authors.lastname: Owens
authors.affiliation: Department of Dermatology, Royal Liverpool and Broadgreen University Hospitals, Liverpool, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Parslew
authors.affiliation: Department of Dermatology, Faculty of Medicine Siriraj Hospital, Mahidol University, Nakhon Pathom, Thailand.
authors.forename: Leena
authors.initials: L
authors.lastname: Chularojanamontri
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059026:Diagnostic Self Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000523:psychology* / Q000532:radiotherapy*; D011788:Quality of Life; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014467:Ultraviolet Therapy; D055815:Young Adult
keywords: assessment; psoriasis; response distribution; simplified psoriasis index; validity