EARLY UNDIFFERENTIATED CONNECTIVE-TISSUE DISEASE

Objective. To examine the musculoskeletal manifestations in a large co hort of patients (n = 410) diagnosed with either a well-established co nnective tissue disease (CTD) (n = 197) or an early undifferentiated C TD (n = 213) with a symptom duration of <1 year. This study was aimed at determining the predictive value of demographic, clinical, and labo ratory features on outcome in patients with unexplained polyarthritis (UPA) (from the early undifferentiated CTD cohort; n 67) or rheumatoid arthritis (RA) (from the well-established CTD cohort; n = 57), over a 5-year followup period. Methods. Patients from both cohorts were asse ssed at years 1, 3, and 5. At the study visits, clinical data were col lected in a standardized manner, and sera were obtained and stored. A priori criteria were established for patient ascertainment and diagnos is over the duration of the study, Standard statistics were used for c omparisons of baseline characteristics in patients diagnosed as having systemic lupus erythematosus, RA, undifferentiated CTD, and UPA at en try into the cohorts. Baseline features in patients with UPA were exam ined according to the different subsequent outcomes (RA, CTD, or undif ferentiated CTD, remission [nonpersistent], or persistent or active UP A). Baseline features in patients with RA whose disease remained activ e versus those in whom remission was attained were also examined. Two multivariable analyses, classification trees and polychotomous logisti c regression, were performed to predict disease outcomes over time. Re sults. The overall rate of ascertainment for the 410 patients ranged f rom 90% at year 1 to 71% at year 5. Patients with established CTDs sho wed a tendency for more stable diagnoses than those with early undiffe rentiated CTDs (90-100% versus 45-70%). Consistent baseline predictors of persistent active disease among patients with RA, in both univaria te and multivariable analyses, were higher joint counts for pain and t enderness and higher erythrocyte sedimentation rate (ESR). In similar to 20% of patients who were classified as having RA when they original ly entered the cohort, the disease was in remission at 5 years. Twenty percent of the patients originally classified as having UPA developed RA over the duration of the study. These patients tended to be older and to have swelling of small joints at baseline. However, a consisten t pattern of predictive variables could not be identified in the multi variable analyses, other than at year 1 (higher small joint counts for swelling and higher ESR). Conclusion. Baseline features (joint counts and ESR) among RA patients were variously predictive of persistently active disease at years 1-5. Consistent baseline predictors of outcome among the patients with UPA only emerged at year 1. Remission occurre d in similar to 20% of RA patients, whereas a similar percentage of pa tients with UPA developed RA. These findings have implications with re gard to treatment decisions in patients with early RA and/or UPA.