Hypertension, comorbidities, and fracture type in older adults: a mediation analysis

Abstract

Introduction: Fragility fractures in older adults often coexist with comorbidities, affecting their location and severity.

Objective: To analyze whether the number of comorbidities acts as a mediator in the association between hypertension and fragility fracture type in older adults.

Materials and methods: A cross-sectional study based on secondary data from 719 adults aged ≥50 years with non-vertebral fragility fractures. Hayes’ PROCESS model 4 was used to assess whether the total number of comorbidities mediated the association between hypertension and fracture type (upper vs. lower limb). Linear and logistic regressions were adjusted for age, sex, diabetes, dyslipidemia, smoking, and calcium/vitamin D supplementation. Bootstrap resampling with 5000 iterations was applied. Results were illustrated in a mediation model diagram to represent the theoretical analytical framework.

Results: Hypertension (B=1.35; p<0.001), diabetes mellitus (B=1.09; p<0.001), dyslipidemia (B=1.36; p<0.001), and vitamin D use (B=0.73; p<0.001) were associated with a higher number of comorbidities. In the logistic regression, a direct positive association between hypertension and upper limb fractures was observed (B=0.43; p=0.042), along with a significant indirect association mediated by comorbidities (B=–0.48; 95% CI: –0.73 to –0.28). A higher number of comorbidities was associated with lower limb fractures (B=–0.36; p<0.001). Sex (B=–0.50; p=0.012), dyslipidemia (B=0.82; p<0.001), smoking (B=0.42; p=0.033), and low calcium intake (B=–0.71; p=0.008) were also significant.

Conclusions: Hypertension was associated with upper limb fractures; however, this association was attenuated or reversed in the presence of multiple comorbidities, favoring lower limb fractures.