title: Validation of Stevens-Johnson syndrome or toxic epidermal necrolysis diagnoses in the Clinical Practice Research Datalink.
abstract: OBJECTIVE
  To evaluate the validity of recorded diagnoses of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in the Clinical Practice Research Datalink (CPRD).
  
  
  METHODS
  We identified patients with a diagnosis of SJS or TEN between 1995 and 2013 in the CPRD. We reviewed information from patient records, free text, and hospital episode statistics (HES) data, and excluded patients with no indication of a secondary care referral. Remaining patients were classified as probable, possible, or unlikely cases of SJS/TEN by two specialised clinicians or based on pre-defined classification criteria. We quantified positive predictive values (PPV) for all SJS/TEN patients and for patients categorised as 'probable/possible' cases of SJS/TEN, based on a representative subsample of 118 patients for whom we had unequivocal information (original discharge letters or HES data).
  
  
  RESULTS
  We identified 1324 patients with a diagnosis of SJS/TEN, among whom 638 had a secondary care referral recorded. Of those, 565 were classified as probable or possible cases after expert review. We calculated a PPV of 0.79 (95% CI, 0.71-0.86) for all SJS/TEN patients with a recorded secondary care referral, and a PPV of 0.87 (95% CI, 0.81-0.93) for probable/possible cases. After excluding 14 false positive patients, our study population consisted of 551 SJS/TEN patients.
  
  
  CONCLUSIONS
  Diagnoses of SJS/TEN are recorded with moderate diagnostic accuracy in the CPRD, which was substantially improved by additional expert review of all available information. We established a large population-based SJS/TEN study population of high diagnostic validity from the CPRD. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Basel Pharmacoepidemiology Unit, Division of Clinical Pharmacy and Epidemiology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland.|Hospital Pharmacy, University Hospital Basel, Basel, Switzerland.
authors.forename: Noel
authors.initials: N
authors.lastname: Frey
authors.affiliation: Allergology, University Hospital Basel, Basel, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bircher
authors.affiliation: Internal Medicine, Zuger Kantonsspital, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Bodmer
authors.affiliation: Boston Collaborative Drug Surveillance Program, Boston University School of Public Health, Lexington, MA, USA.
authors.forename: Susan S
authors.initials: SS
authors.lastname: Jick
authors.affiliation: Basel Pharmacoepidemiology Unit, Division of Clinical Pharmacy and Epidemiology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland.|Hospital Pharmacy, University Hospital Basel, Basel, Switzerland.|Boston Collaborative Drug Surveillance Program, Boston University School of Public Health, Lexington, MA, USA.
authors.forename: Christoph R
authors.initials: CR
authors.lastname: Meier
authors.affiliation: Basel Pharmacoepidemiology Unit, Division of Clinical Pharmacy and Epidemiology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland.|Hospital Pharmacy, University Hospital Basel, Basel, Switzerland.
authors.forename: Julia
authors.initials: J
authors.lastname: Spoendlin
mesh_terms: D016208:Databases, Factual / Q000706:statistics & numerical data*; D006801:Humans; D017891:Pharmacoepidemiology / Q000379:methods*; D011237:Predictive Value of Tests; D012017:Referral and Consultation / Q000706:statistics & numerical data*; D013262:Stevens-Johnson Syndrome / Q000175:diagnosis* / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology
keywords: CPRD; Stevens-Johnson syndrome; pharmacoepidemiology; positive predictive value; toxic epidermal necrolysis; validation; validity