Sensory and Clinical Characterization of Acute and Chronic Pain in Hemophilia: Identification of Distinct Pain Phenotypes.

BACKGROUND: Pain is a major clinical problem in hemophilia, traditionally assessed in terms of intensity and frequency. However, the sensory characteristics of pain and patient-perceived differences between acute and chronic pain remain insufficiently explored. This study aimed to systematically characterize the sensory and clinical features of acute and chronic pain in people with hemophilia and to determine whether clinically meaningful differences exist between these pain types. METHODS: In this cross-sectional study, people with hemophilia followed at a comprehensive care center were evaluated using the Pain Quality Assessment Scale (PQAS) and the Brief Pain Inventory (BPI). K-means cluster analysis was applied to PQAS scores to identify pain phenotypes, with cluster numbers determined using hierarchical analysis and dendrogram inspection. RESULTS: Acute pain demonstrated higher intensity and a more multidimensional sensory profile compared with chronic pain. Descriptors such as "dull," "deep," "intense," and "hot" were more prominent in acute episodes. Chronic pain showed lower intensity but a persistent pattern associated with stiffness after periods of inactivity and prolonged standing. Three distinct clusters were identified for acute pain and two for chronic pain, supporting heterogeneous pain phenotypes. A substantial proportion of patients reported pain in multiple joints, suggesting the possible coexistence of nociceptive and sensitization-related mechanisms. CONCLUSION: Acute and chronic pain in hemophilia represent distinct sensory and clinical entities. Beyond differences in duration, these findings suggest differing underlying mechanisms and highlight the importance of accurate pain differentiation to guide individualized and interdisciplinary pain management strategies.