Sex differences in joint pain, limb function and quality of life among patients with Kashin-Beck disease in Northwest China

Background: Kashin–Beck disease (KBD) remains a significant public health challenge in northwestern China, where chronic joint pain and functional limitations severely compromise quality of life (QoL). Despite growing recognition of sex-related disparities in musculoskeletal conditions, sex-specific differences in pain, limb function, and QoL among KBD patients remain underexplored. This study aimed to investigate these disparities to enhance understanding and guide tailored management. Methods: A cross-sectional study was conducted among 329 patients with KBD (160 males and 169 females) in endemic areas of Shaanxi Province, Northwest China. Validated assessment tools were employed, including the Graded Chronic Pain Scale (GCPS), Quick Disabilities of the Arm, Shoulder, and Hand Questionnaire (QuickDASH), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and three-level EuroQol five-dimensional questionnaire (EQ-5D-3 L), to evaluate pain, limb function, and QoL. Sex differences were analyzed using Chi-square tests, independent-sample t-tests, and Mann-Whitney U tests. Results: Female patients exhibited significantly poorer upper-limb function than males (QuickDASH: 55.4 ± 23.7 vs. 39.1 ± 24.1; p < 0.001), surpassing the minimal clinically important difference (MCID) threshold of 14.0. Pain distribution varied by sex: females reported more hand/foot pain, whereas males more commonly experienced knee/ankle pain (all p < 0.05). Although differences in pain intensity (6.9 ± 1.6 vs. 6.5 ± 1.6; p = 0.016) and lower-limb function (WOMAC: 50.6 ± 20.6 vs. 45.2 ± 18.1; p = 0.012) were statistically significant, they did not exceed the corresponding MCID thresholds (1.0 and 16.1, respectively). Moreover, females had significantly poorer QoL scores (EQ-5D-3 L: 0.589 ± 0.252 vs. 0.684 ± 0.233, p < 0.001; EQ-VAS: 45.7 ± 21.7 vs. 52.7 ± 19.1, p = 0.002). Conclusions: This study revealed clinically significant sex differences in upper-limb function among KBD patients in Northwest China, with females experiencing greater impairment. While other observed sex differences in pain and lower-limb function were statistically significant, they lacked clinical meaningfulness. The distinct patterns of pain distribution and the significantly poorer QoL observed in females warrant clinical attention. These findings highlight the importance of prioritizing upper limb rehabilitation in treatment strategies, particularly for female patients.