American College of Rheumatology Criteria at Inception, and Accrual over 5 Years in the SLICC Inception Cohort

Objective. To determine the frequency of each American College of Rheumatology (ACR) criterion met at time of enrollment, and the increase in each of the criteria over 5 years. Methods. In 2000 the Systemic Lupus International Collaborating Clinics (SLICC) recruited an international inception cohort of patients with systemic lupus erythematosus (SLE; >= 4 ACR criteria) who were followed at yearly intervals according to a standard protocol. Descriptive statistics were used to assess the total and cumulative number of ACR criteria met at each visit. Regression models were done to compare the increase of individual and cumulative criteria as a function of race/ethnicity group, and sex. Results. In all, 768 patients have been followed for a minimum of 5 years. Overall, 59.1% of the patients had an increase in the number of ACR criteria they met over the 5-year period. The mean number of ACR criteria met at enrollment was 5.04 +/- 1.13 and at year 5 was 6.03 +/- 1.42. At enrollment, nonwhite patients had a higher number of ACR criteria (5.19 +/- 1.23) than white patients. The total number of criteria increased in both white and nonwhite ethnicities, but increased more among whites. Males had a slightly lower number of criteria at enrollment compared to females and males accrued fewer criteria at 5 years. Conclusion. In this international inception cohort of SLE patients with at least 4 ACR criteria at entry, there was an accumulation of ACR criteria over the following 5 years. The distribution of criteria both at inception and over 5 years is affected by sex and ethnicity.