Background/Purpose: Sex-related differences in axial spondyloarthritis (axSpA) have been described regarding clinical features, disease burden, and particularly patient-reported outcomes. These differences influence patient management, including diagnostic strategies and referral patterns. However, it remains unclear whether these sex-specific differences represent a distinct feature of axSpA or if similar patterns also occur in the broader population of patients with chronic back pain (CBP) without axSpA. The objective of this study is to assess sex differences in demographic and clinical features, including patient-reported disease activity and functional impairment, among young adults with CBP referred by non-rheumatology specialists.

Methods: A prospective, cross-sectional observational study was conducted between July 2021 and October 2023 as part of the “Strategy for a Hospital Early Referral in Patients with Axial Spondyloarthritis” (SHERPAS) Cohort. Adults aged 18–40 years with CBP ( >3 months duration) referred for spinal magnetic resonance imaging (MRI) by non-rheumatology specialists completed detailed questionnaires capturing demographic characteristics, lifestyle factors and patient-reported outcomes (PROs), including disease activity and functional impairment measured by BASDAI and BASFI. MRI imaging of the spine and sacroiliac joints (SIJ) were performed within two weeks, as well as a consultation with the rheumatologist. Diagnoses were based on expert clinical judgment considering imaging, clinical, and laboratory data. Only patients in whom a diagnosis of axSpA had been ruled out were included. Statistical comparisons by sex were conducted using appropriate parametric or non-parametric tests.

Results: Among 260 patients, 149 (57.3%) were female, and mean age was 34.6±5.6 years. While most demographic and clinical characteristics did not differ significantly by sex (Table 1), marked differences were observed in PROs. Female reported significantly higher overall BASDAI (4.9±2.5 vs 3.6±2.4; p< 0.001) and higher overall BASFI (3.7±2.7 vs 2.8±2.5; p=0.004) versus males. Concerning individual BASDAI items (Figure 1), female reported higher scores in fatigue (5.6 ± 3.1 vs 4.1 ± 2.9; p< 0.001), spinal pain (6.5 ± 3.0 vs 5.1 ± 3.2; p=0.001), peripheral pain (3.4 ± 3.4 vs 1.9 ± 2.7; p < 0.001), and general discomfort/enthesitis (5.2 ± 3.5 vs 3.3 ± 3.1; p < 0.001) than males. Female also had higher functional impairment in BASFI items, particularly showing greater difficulty reaching an object on a shelf (3.0 ± 3.4 vs 1.8 ± 2.8; p=0.002), rising from the floor (4.3 ± 3.7 vs 2.9 ± 3.3; p=0.002), standing for 10 minutes (5.1 ± 3.6 vs 3.7 ± 3.5; p=0.002), climbing 15 steps (3.5 ± 3.5 vs 2.1 ± 3.1; p=0.001) and turning the head over the shoulder (2.6 ± 3.3 vs 1.3 ± 2.4; p< 0.001).

Conclusion: Significant sex differences were observed in the clinical presentation of young adults with CBP, particularly in patient-reported disease activity and functional limitation scores. These findings suggest that sex-related disparities in disease burden are not specific to axSpA, highlighting the need for broader sex-sensitive strategies in the evaluation and management of all young patients with CBP.

Table 1. Characteristics of patients in the SHERPAS cohort stratified by sex

Figure 1. Items of BASDAI (a) and BASFI (b) stratified by sex

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/sex-related-differences-in-clinical-presentation-and-patient-reported-burden-in-chronic-back-pain-are-these-findings-specific-to-axspa-results-from-the-sherpas-cohort/