Why do patients with urinary diversions have an increased risk of bone fracture? A systematic review on risk factors for osteoporosis and bone mineral density loss in this group of patients

Introduction: Patients undergoing radical cystectomy with urinary diversions (UDs) are at increased risk of bone fractures compared to the general population. Although a loss of bone mineral density (BMD) has been described in patients with UDs, we still do not know with certainty why these patients follow this tendency. Objective: We performed a systematic review of the available literature to analyze the prevalence of osteoporosis and bone alterations in patients with ileal UD and the possible associated risk factors. Evidence acquisition: We systematically searched PubMed® and Cochrane Library for original articles published before December 2022 according to PRISMA guidelines. Evidence synthesis: A total of 394 publications were identified. We selected 12 studies that met the inclusion criteria with 496 patients included. Six of the twelve studies showed decreased BMD values. Prevalence of osteoporosis was specified in three articles, with values ranging from 0% to 36%. Risk factors such as age, sex, body mass index, metabolic acidosis and renal function appear to have an impact on bone tissue reduction, while type of UD, follow-up, 25-hydroxyvitamin D and parathormone had less evidence or contradictory data. The heterogeneity of the studies analyzed could led to interpretation bias. Conclusions: UDs are associated with multiple risk factors for osteoporosis and bone fractures. Identifying patients at highest risk and establishing diagnostic protocols in routine clinical practice are essential to reduce the risk of fractures and the resulting complications.