Objective To evaluate the impact of laboratory results on scoring of the Physician Global Assessment (PGA) of disease activity in systemic lupus erythematosus.
Methods Fifty clinical vignettes were presented via an online survey to a group of international lupus experts. For each case, respondents scored the PGA pre and post knowledge of laboratory test results (pre-lab and post-lab PGAs). Agreement between individual assessors and relationships between pre-lab and post-lab PGAs, and PGAs and Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) were determined. Respondents were also asked about factors they incorporate into their PGA determinations.
Results Sixty surveys were completed. The inter-rater PGA reliability was excellent (pre-lab intraclass correlation coefficient (ICC) 0.98; post-lab ICC 0.99). Post-lab PGAs were higher than pre-lab PGAs: median (IQR) pre-lab PGA 0.5 (1.05), post-lab PGA 1 (1.3) (p<0.001), with a median (IQR) difference of 0.2 (0.45). In general, all abnormal labs including elevated anti-double stranded DNA antibody level (dsDNA) and low complement impacted PGA assessment. Cases with weakest correlations between pre-lab and post-lab PGA were characterised by laboratory results revealing nephritis and/or haematological manifestations. Both pre-lab and post-lab PGAs correlated with SLEDAI-2K. However, a significantly stronger correlation was observed between post-lab PGA and SLEDAI-2K. Multiple factors influenced PGA determinations. Some factors were considered by an overwhelming majority of lupus experts, with less agreement on others.
Conclusions We found excellent inter-rater reliability for PGAs in a group of international lupus experts. Post-lab PGA scores were higher than pre-lab PGA scores, with a significantly stronger correlation with the SLEDAI-2K. Our findings indicate that PGA scoring should be performed with knowledge of pertinent laboratory results.
- systemic lupus erythematosus
- outcomes research
- disease activity
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Handling editor Josef S Smolen
CA and AA contributed equally.
Presented at This work was presented as a poster presentation at the 2018 American College of Rheumatology/Association of Rheumatology Professionals Annual Meeting: Aranow C, Askanase A, Huq M, et al. Laboratory Investigation Results Influence Physician’s Global Assessment of Disease Activity in Systemic Lupus Erythematosus (abstract). Arthritis Rheumato. 2018;70 (suppl 10).
Correction notice This article has been corrected since it published Online First. A typographical error has been corrected in the title and the funding statement has been updated.
Contributors Study design: CA, AA, MN. Data collection: CA, AA, MN, AC. Data analysis: CA, AA, MN, SO, AC, EFM, MH. Interpretation of findings: CA, AA, MN, SO, AC, EFM, MH. Preparation of manuscript: CA, AA, MN, SO, AC, EFM, MH. All authors read and approved the final manuscript. Please note that CA and AA contributed equally to this work.
Funding This work was in part supported by funding from the Lupus Research Alliance/Lupus Therapeutics (LRA/LT) to Cynthia Aranow and Anca Askanase. Mandana Nikpour holds an NHMRC Fellowship (APP1126370).
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval Ethics approval for the study was obtained from the Human Research Ethics Committee of St Vincent’s Hospital Melbourne, Australia.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.