Sequences of Regressions Distinguish Nonmechanical from Mechanical Associations between Metabolic Factors, Body Composition, and Bone in Healthy Postmenopausal Women

Sex-specific associations between cardiovascular risk factors and physical function: the Gambian Bone and Muscle Ageing Study

BACKGROUND

In Sub-Saharan Africa, the prevalence of obesity, cardiovascular disease (CVD) and impaired physical function are increasing due to rapid urbanization. We investigated sex differences in associations between cardiac workload, arterial stiffness, peripheral vascular calcification (PVC) and physical function in Gambian adults.

METHODS

A total of 488 Gambians aged 40-75+ years were recruited (men: 239; and women: 249). Supine blood pressure and heart rate were measured to calculate rate pressure product and pulse pressure. Presence of PVC was determined from tibia peripheral quantitative computed tomography scans. Physical function was assessed by chair rise test (CRT), single two-legged jump (s2LJ) and hand grip strength (HGS). Body composition was measured by dual-energy x-ray absorptiometry; body size corrections were used to calculate fat mass index (FMI) and appendicular lean mass index (ALMI). Estimated glomerular filtration rate (eGFR) was measured from fasting blood samples. The relationship between rate pressure product, pulse pressure or presence of PVC (independent variable) with physical function parameters (dependent variable) was tested using linear regression. Sex-interactions were tested (p-int) adjusting for age, eGFR and ALMI/FMI. Results were expressed as mean differences between men and women with 95% confidence intervals. Mediation analyses used ALMI/FMI as mediator.

RESULTS

Women weighed less (54.7 kg ± 10.3 vs. 59.9 kg ± 10.3) and were shorter (157.8 cm ± 6.0 vs. 169.2 cm ± 7.0) compared with men (both P < 0.0001). Women had higher FMI (6.8 kg/m2  ± 2.9 vs. 2.9 kg/m2  ± 2.0, P < 0.0001) and eGFR (263.7 mL/min/1.73 m2  ± 133.1 vs. 237.6 mL/min/1.73 m2  ± 134.6), but lower ALMI (6.2 kg/m2  ± 0.7 vs. 8.02 kg/m2  ± 1.0, P < 0.0001) compared with men. There were significant mean differences between men and women in rate pressure product and s2LJ power (-1.08 [-1.21, -0.95]) and force (-0.57 [-0.63, -0.51]), only after adjusting for age, eGFR and FMI. There were significant mean differences in the associations between pulse pressure and CRT power (-0.28 [-0.31, -0.25]), s2LJ power (-1.07 [-1.20, -0.93]) and HGS (-11.94 [-13.35, -10.54]); these differences were greater after adjusting for age, eGFR and FMI, than ALMI. There were similar differences in the associations between PVC and physical function parameters. In men, FMI mediated the association between rate pressuree product and CRT power (P = 0.002), s2LJ force (P < 0.001) and s2LJ power (P = 0.001). ALMI did not mediate associations for either men or women.

CONCLUSIONS

Multiple risk factors for CVD were associated with poorer physical function in men and were mediated by FMI. There is a need to identify strategies to slow/prevent the rising CVD burden and poor physical function in Sub-Saharan Africa.

Intervening to eliminate the centre-effect variation in home dialysis use: protocol for Inter-CEPt-a sequential mixed-methods study designing an intervention bundle

INTRODUCTION

Use of home dialysis by centres in the UK varies considerably and is decreasing despite attempts to encourage greater use. Knowing what drives this unwarranted variation requires in-depth understanding of centre cultural and organisational factors and how these relate to quantifiable centre performance, accounting for competing treatment options. This knowledge will be used to identify components of a practical and feasible intervention bundle ensuring this is realistic and cost-effective.

METHODS AND ANALYSIS

Underpinned by the non-adoption, abandonment, scale-up, spread and sustainability framework, our research will use an exploratory sequential mixed-methods approach. Insights from multisited focused team ethnographic and qualitative research at four case study sites will inform development of a national survey of 52 centres. Survey results, linked to patient-level data from the UK Renal Registry, will populate a causal graph describing patient and centre-level factors, leading to uptake of home dialysis and multistate models incorporating patient-level treatment modality history and mortality. This will inform a contemporary economic evaluation of modality cost-effectiveness that will quantify how modification of factors facilitating home dialysis, identified from the ethnography and survey, might yield the greatest improvements in costs, quality of life and numbers on home therapies. Selected from these factors, using the capability, opportunity and motivation for behaviour change framework (COM-B) for intervention design, the optimal intervention bundle will be developed through workshops with patients and healthcare professionals to ensure acceptability and feasibility. Patient and public engagement and involvement is embedded throughout the project.

ETHICS AND DISSEMINATION

Ethics approval has been granted by the Health Research Authority reference 20-WA-0249. The intervention bundle will comprise components for all stake holder groups: commissioners, provider units, recipients of dialysis, their caregivers and families. To reache all these groups, a variety of knowledge exchange methods will be used: short guides, infographics, case studies, National Institute for Health and Care Excellence guidelines, patient conferences, 'Getting it Right First Time' initiative, Clinical Reference Group (dialysis).