Classification of rheumatologic opinion on early inflammatory arthritis: harmonization of a heterogeneous standard.
OBJECTIVE
Interrater variability limits rheumatologic opinion as a reference standard for early inflammatory arthritis (IA) classification. The study objectives were to determine whether rheumatologic opinion is associated with potential early IA classification methods despite high interrater variability, and to compare the relative strengths of those associations.


METHODS
Eighteen rheumatologists independently classified 30 initial rheumatology presentation summaries as early IA or not and recommended a pharmacotherapy. Case fulfillment of the following classification methods was independently determined: early referral to rheumatology recommendation for rheumatoid arthritis (ERRR), common early IA cohort inclusion criteria (CEAC), and prevalent IA classification criteria (American College of Rheumatology [ACR]/European Spondylarthropathy Study Group [ESSG]). Associations between rheumatologic opinion, disease-modifying antirheumatic drug (DMARD) recommendation, and each classification method were determined.


RESULTS
Participating rheumatologists published on early IA and represented 3 continents. The median case was age 43 (interquartile range [IQR] 30-53) years, had 40 (IQR 24-104) weeks of symptoms, 60 (IQR 18-120) minutes of morning stiffness, a swollen joint count of 6 (IQR 1-13), and an erythrocyte sedimentation rate of 25 (IQR 10-51) mm/hour. The mean ± SD multiple-rater kappa for rheumatologic opinion on early IA was 0.16 ± 0.02. The common odds ratios for associations between rheumatologic opinion and ERRR, CEAC, and ACR/ESSG were 10.3 (95% confidence interval [95% CI] 4.6-23.2), 4.4 (95% CI 2.5-7.7), and 0.7 (95% CI 0.4-1.1), respectively. Odds ratios for associations between DMARD recommendation and ERRR, rheumatologic opinion, CEAC, and ACR/ESSG were 18.7 (95% CI 8.1-43.2), 10.6 (95% CI 6.0-18.8), 2.8 (95% CI 1.7-4.6), and 0.5 (95% CI 0.3-0.7), respectively.


CONCLUSIONS
Classification methods can be used to harmonize rheumatologic opinion of early IA despite high interrater variability. The ERRR is very strongly associated with both rheumatologic opinions of early IA and DMARD treatment recommendations.
Tavares
Ruben
R
McMaster University, Hamilton, Ontario, Canada. ruben.tavares@sympatico.ca
Wells
George A
GA
Scarf
Joel
J
Cagaanan
Ria
R
Bykerk
Vivian P
VP
Bell
Mary J
MJ
D000328:Adult; D000367:Age Factors; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010820:Physicians / Q000592:standards*; D017410:Practice Guidelines as Topic / Q000592:standards; D012219:Rheumatology / Q000379:methods / Q000592:standards*; D016037:Single-Blind Method
D018501:Antirheumatic Agents