Fragility fractures in psoriatic arthritis patients: a matched retrospective cohort study

Objective: To compare incidental fragility fractures in psoriatic arthritis (PsA) patients with matched controls from a university hospital.

Methods: Consecutive PsA patients were matched (age and sex) with controls (1:2). Follow-up began at index date, defined as the date of PsA diagnosis for cases and their respective controls, until the last hospital visit, death or the end of the study (31 December 2017). Electronic medical records were reviewed for osteoporotic fractures. Incidence rates per 100,000 persons-years (PY) of distinct types of fractures after index dates were calculated and compared between groups. A multivariate Cox regression analysis was performed to investigate determinants of fractures.

Results: Ninety-two PsA patients and 184 controls were included. No difference was found in the overall fracture incidence rate per 100,000 PY between PsA and controls (1020 95% CI 510-1930, vs 870 95% CI 520-1390, p = 0.36). Vertebral fractures were numerically more frequent in PsA patients with an incidence rate of 1020 (95% CI 510-1930) per 100,000 PY versus 460 (95% CI 240-920), per 100,000 PY in the control group but it did not reach statistical significance (p = 0.06). In the Cox regression analysis, after adjusting for bisphosphonate use, only age (HR 1.10, 1.05-1.16, p < 0.001) and female sex (HR 3.94, 1.11-13.91, p = 0.03) were associated with fractures while PsA diagnosis and use of glucocorticoids were not.

Conclusion: In this cohort of PsA patients, no overall increased risk of fractures was found in comparison with matched controls. Key Points • PsA could have different effects on bone, leading to confusing results in bone densitometry readings contributing to the difficulty in establishing the real prevalence of OP in PsA. • Vertebral fractures were more frequent in PsA patients compared to controls, but it did not reach statistical significance. No difference was found in the overall fracture incidence rate.