Patients whose kidneys have failed and who depend on maintenance hemodialysis face a quiet, progressive erosion of the physical abilities most people take for granted: rising from a chair, walking across a room, keeping balance while standing. A new prospective observational study from a hemodialysis center in Brazil, published in BMC Nephrology, has now identified two factors that independently track with that erosion. Among 103 patients followed for an average of 18.6 months, lower bone mineral density measured at the femur and a longer cumulative time on dialysis were each associated with a decline in physical performance, even after accounting for other clinical, laboratory, and body-composition measures.
The research team, led by Elisângela Andrade Assis Madeira and Vanessa Amaral Mendonça, recruited 130 consecutive eligible patients and assessed them at baseline between May 2019 and December 2024. Twenty-seven patients, or 20.8 percent, were lost to follow-up for reasons including kidney transplantation, transfer to another center, death, refusal to continue, and recovery of renal function. That left 103 participants, with a mean age of 52.1 years and 54.4 percent male, who completed both the baseline and follow-up evaluations. During follow-up, 18 participants, or 17.5 percent, experienced physical performance decline, while the remaining 85 maintained their performance.
What distinguishes this study from earlier work is how decline was defined. Rather than relying on any drop in score, the researchers used the minimal detectable change, or MDC, of the Short Physical Performance Battery, a threshold of 1.7 points previously established for patients on maintenance hemodialysis. The MDC represents the smallest change that exceeds the instrument’s measurement error, giving reasonable confidence that an observed difference reflects a true change in physical performance rather than measurement noise. Participants whose SPPB score fell by more than 1.7 points between baseline and follow-up were classified as having declined; those with smaller reductions, no change, or improvement were classified as having maintained performance. The authors note that the MDC should not be confused with the minimal clinically important difference, and that no such clinically important threshold has been established for the SPPB in this population.
The SPPB itself is a compact but informative instrument. It evaluates lower limb function through three short tests: static balance in progressively narrower stances, the time needed to walk four meters at a normal pace, and the time needed to rise from a chair and sit down five times without using the hands. Each component is scored from 0 to 4, yielding a total from 0 to 12, with lower scores previously linked to higher risks of all-cause mortality and hospitalization in hemodialysis patients. Participants also completed the 60-second sit-to-stand test, handgrip strength measurement with a JAMAR dynamometer on the limb without an arteriovenous fistula, and whole-body dual-energy X-ray absorptiometry, or DEXA, to quantify fat mass, lean mass, and bone mineral density. Routine laboratory parameters, including Kt/V, calcium, phosphorus, vitamin D, parathyroid hormone, C-reactive protein, and alkaline phosphatase, were drawn from medical records.
At baseline, the group that would go on to decline differed from the group that would not in several respects. Participants with later physical performance decline were significantly older, with a p-value of 0.025, and had lower total and femoral bone mineral density, with p-values of 0.02 and 0.004 respectively. They also performed worse on the 60-second sit-to-stand test, at p = 0.006. No significant differences emerged between the groups in sex, hypertension, diabetes mellitus, or the other analyzed variables. Across the whole sample, the change in SPPB score ranged from a loss of 8 points to a gain of 7; participants who declined had a mean change of minus 3.7 points, while those who maintained performance averaged a gain of 0.5 points.
To isolate the factors most strongly tied to decline, the researchers first ran univariable logistic regressions on candidate variables including age, sex, sarcopenia, hemodialysis vintage, follow-up duration, total and femoral bone mineral density, phosphorus, and sit-to-stand performance. Older age and longer hemodialysis vintage raised the odds of decline, while higher total and femoral bone mineral density and better sit-to-stand performance lowered them. Because total and femoral bone mineral density were highly correlated, with a Pearson correlation coefficient of 0.829, femoral density was carried forward as the representative bone measure. With only 18 outcome events, the team then fitted a multivariable penalized logistic regression with Firth correction, a technique designed to stabilize estimates and reduce small-sample bias, and derived confidence intervals from 1,000 bootstrap resamples.
In that final model, two variables remained independently associated with decline. Each 1 mg/cm² increase in femoral bone mineral density was associated with a 0.3 percent reduction in the odds of physical performance decline, an odds ratio of 0.997 with a 95 percent confidence interval of 0.991 to 0.999. Expressed per 100 mg/cm² for interpretability, this corresponds to roughly 26 percent lower odds. Each additional month of hemodialysis was associated with a 0.9 percent increase in the odds of decline, an odds ratio of 1.009 with a confidence interval of 1.001 to 1.039. Age and sit-to-stand performance, by contrast, did not remain significant in the multivariable model. The model showed an apparent C-statistic of 0.82 and an optimism-corrected value of 0.78 after bootstrap validation, a level of discrimination the authors caution should be interpreted cautiously given the limited number of events.
The findings carry physiological weight. Lower bone mineral density may reflect the cumulative burden of chronic kidney disease–mineral and bone disorder, reduced mechanical loading, muscle impairment, and frailty, all of which have been linked to poorer physical performance in this population. Femoral bone mineral density has previously been associated with skeletal muscle mass and sarcopenia in hemodialysis patients, as well as with lower limb muscle strength, and bone impairment has been tied to impaired mobility and balance, limitations in daily activities, and higher risks of falls, fractures, and functional dependence. Notably, other body composition indicators such as lean mass and fat percentage showed no significant association with the outcome, consistent with evidence that muscle mass alone does not adequately explain physical function in hemodialysis patients and underscoring the value of structural measures like bone density.
The association with hemodialysis vintage aligns with longitudinal evidence that cumulative exposure to dialysis accompanies progressive loss of physical function, potentially through chronic inflammation, malnutrition, and the burden of comorbidities. The authors frame these results as support for incorporating systematic physical function assessment into routine hemodialysis care, using simple standardized instruments such as the SPPB to catch changes early and guide multidisciplinary interventions aimed at preserving independence. They also acknowledge important limitations: attrition from death, transplantation, and transfers raises the possibility of attrition bias, and informative censoring and survivor bias cannot be ruled out. Follow-up duration varied among participants because of scheduling constraints at the dialysis center; although it did not differ between groups and was not associated with decline in univariable analysis, participants with longer follow-up may have had more opportunity to cross the MDC threshold. With those caveats, the study offers a measured but practically useful message: skeletal health and time on dialysis together mark patients who are most vulnerable to losing physical function, and regular performance testing may help identify them before the decline becomes entrenched.
Subject of Research: Predictors of physical performance decline in patients receiving maintenance hemodialysis
Article Title: Predictors of physical performance decline in patients receiving maintenance hemodialysis: a prospective observational study
Article References: Madeira, E. A. A., Santos, J. N. V., Silva, V. E. R., Martins, I. C. M., Rodrigues, V. G. B., Silva Lage, V. K. D., Machado, A. H. S., de Castro Pereira, J. G., Alves, F. L., Prates, M. C. S. M., Maciel, E. H. B., Costa, H. S., de Alcantara, M. A., Neves, C. D. C., de Moura, R. M. F., Taiar, R., Lacerda, A. C. R., Figueiredo, P. H. S., & Mendonça, V. A. (2026). Predictors of physical performance decline in patients receiving maintenance hemodialysis: a prospective observational study. BMC Nephrology, 27(1), Article 626. https://doi.org/10.1186/s12882-026-05361-7
Image Credits: AI Generated
DOI: 10.1186/s12882-026-05361-7
Keywords: hemodialysis, physical performance, bone mineral density, SPPB, kidney failure, sarcopenia, functional decline, dialysis vintage, observational study, DEXA, chronic kidney disease, rehabilitation
News Source: Jerry Hayes. (October 29, 2026). Bone Density and Dialysis Duration Signal Physical Decline in Hemodialysis Patients. Scienmag.
