title: Does expert opinion match the operational definition of the Lupus Low Disease Activity State (LLDAS)? A case-based construct validity study.
abstract: To evaluate the construct validity of the Lupus Low Disease Activity State (LLDAS), a treatment target in systemic lupus erythematosus (SLE).
  
  
  
  Fifty SLE case summaries based on real patients were prepared and assessed independently for meeting the operational definition of LLDAS. Fifty international rheumatologists with expertise in SLE, but with no prior involvement in the LLDAS project, responded to a survey in which they were asked to categorize the disease activity state of each case as remission, low, moderate, or high. Agreement between expert opinion and LLDAS was assessed using Cohen's kappa.
  
  
  
  Overall agreement between expert opinion and the operational definition of LLDAS was 77.96% (95% CI: 76.34-79.58%), with a Cohen's kappa of 0.57 (95% CI: 0.55-0.61). Of the cases (22 of 50) that fulfilled the operational definition of LLDAS, only 5.34% (59 of 22 × 50) of responses classified the cases as moderate/high activity. Of the cases that did not fulfill the operational definition of LLDAS (28 of 50), 35.14% (492 of 28 × 50) of responses classified the cases as remission/low activity. Common reasons for discordance were assignment to remission/low activity of cases with higher corticosteroid doses than defined in LLDAS (prednisolone ≤ 7.5mg) or with SLEDAI-2K >4 due to serological activity (high anti-dsDNA antibody and/or low complement).
  
  
  
  LLDAS has good construct validity with high overall agreement between the operational definition of LLDAS and expert opinion. Discordance of results suggests that the operational definition of LLDAS is more stringent than expert opinion at defining a low disease activity state.
authors.affiliation: School of Clinical Sciences, Monash University, Melbourne, Australia. Electronic address: vera.golder@monash.edu.
authors.forename: Vera
authors.initials: V
authors.lastname: Golder
authors.affiliation: Department of Medicine, Melbourne University, Melbourne, Australia.
authors.forename: Molla
authors.initials: M
authors.lastname: Huq
authors.affiliation: School of Clinical Sciences, Monash University, Melbourne, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Franklyn
authors.affiliation: Department of Medicine, Melbourne University, Melbourne, Australia.
authors.forename: Alicia
authors.initials: A
authors.lastname: Calderone
authors.affiliation: Rheumatology Division, National University Hospital, Singapore, Singapore.
authors.forename: Aisha
authors.initials: A
authors.lastname: Lateef
authors.affiliation: Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Chak Sing
authors.initials: CS
authors.lastname: Lau
authors.affiliation: Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Alfred Lok Hang
authors.initials: ALH
authors.lastname: Lee
authors.affiliation: Joint and Bone Centre, University of Santo Tomas Hospital, Manila, Philippines.
authors.forename: Sandra Teresa V
authors.initials: STV
authors.lastname: Navarra
authors.affiliation: Department of Medicine, Melbourne University, Melbourne, Australia.
authors.forename: Timothy
authors.initials: T
authors.lastname: Godfrey
authors.affiliation: Department of Medicine, Melbourne University, Melbourne, Australia.
authors.forename: Shereen
authors.initials: S
authors.lastname: Oon
authors.affiliation: School of Clinical Sciences, Monash University, Melbourne, Australia.
authors.forename: Alberta Yik Bun
authors.initials: AYB
authors.lastname: Hoi
authors.affiliation: School of Clinical Sciences, Monash University, Melbourne, Australia.
authors.forename: Eric Francis
authors.initials: EF
authors.lastname: Morand
authors.affiliation: Department of Medicine, Melbourne University, Melbourne, Australia.
authors.forename: Mandana
authors.initials: M
authors.lastname: Nikpour
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D055815:Young Adult
keywords: Outcome measures; Systemic lupus erythematosus