Background <p>Brucellar Spondyloarthritis (BrSpA), a common and disabling complication of brucellosis, often develops as the disease transitions from its acute systemic phase. However, the specific risk factors and clinical patterns heralding this shift are poorly understood. This study aimed to identify stage-dependent risk factors for BrSpA and to elucidate the paradoxical clinical signs associated with its development.</p> Methods <p>In this retrospective, multicenter study, we analyzed data from 642 participants, comprising a BrSpA group (<i>n</i> = 187), a non-osteoarticular brucellosis group (<i>n</i> = 176), and a healthy control group (<i>n</i> = 279). Baseline data, clinical symptoms and laboratory findings were collected, summarized and analyzed. The significance of the data was determined using t-test or Pearson chi-square test, and logistic regression test was used to calculate the odds ratio (OR) to characterize the relevant risk factors affecting the development of BrSpA.</p> Results <p>When compared to the non-osteoarticular brucellosis group, progression to the subacute/chronic stages, lower educational attainment, fatigue, and musculoskeletal pain were independent risk factors for BrSpA. In this same comparison, factors reflecting acute systemic inflammation (e.g., anorexia, elevated C-reactive protein [CRP]) were paradoxically associated with a lower risk of BrSpA (OR &lt; 1). In contrast, when the BrSpA group was compared to healthy controls, these same factors were confirmed as significant risk factors (OR &gt; 1).</p> Conclusion <p>The development of BrSpA in brucellosis is marked by a paradoxical clinical profile. Our findings demonstrate that the resolution of systemic inflammatory signs should not be uniformly interpreted as recovery. Instead, this pattern may represent a critical transition to focal disease, serving as a key warning sign for clinicians to heighten vigilance and initiate proactive diagnosis to prevent long-term complications.</p>