Quantitative variables were described as mean ± SD and qualitative data as number and percentage. Kolmogorov–Smirnov test was performed to compare BP population distribution. The Kolmogorov–Smirnov test works by comparing the cumulative distribution of the two data sets and computes a P value that depends on the largest discrepancy between distributions. In contrast to Mann–Whitney test that is mostly sensitive to changes in the median, the Kolmogorov–Smirnov test is sensitive to changes in the shape, spread, or median of the two distributions. Chi2 tests were used for comparison between qualitative variables and nonparametric, Mann–Whitney tests for comparison between quantitative values. Owing to absence of normal distribution, comparisons between groups were performed using Spearman’s correlation coefficient to explore the relationship between continuous variables (BPDAI with immunological parameters, immunological parameters in serum with those in BF). A P value <0.05 was considered statistically significant. Multivariate analyses were then performed using stepwise logistic regressions, with enter and removal limits set at 0.20 and factors significant at P = 0.20 included.