Background: Low disease activity state (LDAS) has been linked to a significant reduction in flares and damage accrual in patients with systemic lupus erythematosus (SLE); however, the effect of LDAS on the risk of vertebral fractures (VFs) in subjects with SLE is unknown, considering that low bone mineral density (BMD) and VF are frequent in SLE.
Objective: to evaluate whether achieving LDAS ≥50% of the observation time prevents new VF and BMD changes in Mestizo women.
Methods: We carried out a longitudinal, observational, and retrospective study. Mestizo women with SLE were included for a median of an 8-year follow-up. LDAS was described as Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score ≤4, prednisone ≤7.5 mg/day, and stable immunosuppressive therapies. BMD measurements and lateral thoracic and lumbar radiographs for a semiquantitative analysis for VF were assessed at baseline and during the follow-up. Uni- and multivariable interval-censored survival regression models were carried out.
Results: We included 110 patients: 35 (31.8%) had new VF. A total of 56 patients (50.1%) achieved LDAS ≥50% of the time during the follow-up and achieved a significantly lesser risk of incident VF (HR = 0.16; 95% CI, 0.06-0.49). After adjusting by age, BMI, menopause, prevalent VF, baseline BMD, cumulative glucocorticoid use, and anti-osteoporotic therapy, LDAS-50 was significantly related to a decrease in the risk of a new VF (HR = 0.39; 95% CI, 0.16-0.98). There was no association between LDAS and BMD measurement changes. When only patients on LDAS but not in remission (n = 43) were evaluated for the risk of incident VF, both uni- and multivariate analyses were significant (HR = 0.12; 95 CI, 0.04-47; p = 0.001, and HR = 0.26; 95% CI, 0.7-0.88; p = 0.03).
Conclusions: LDAS ≥50% of the time was significantly associated with a diminished risk of new VF in Mestizo women with SLE, even in patients not in remission. However, LDAS did not help modify BMD changes over time.
Keywords: Systemic lupus erythematosus; bone mineral density; incident vertebral fractures; low disease activity.