Age-related trajectory pattern of handgrip strength and mortality in patients on hemodialysis

Abstract Background and Aims Muscle weakness is a factor known to worsen prognosis in patients on hemodialysis [1], and the prevention of muscle weakness is extremely important in disease management. In particular, understanding age-related changes in muscle strength can be advantageous for long-term interventions. A previous study on community-dwelling older adults examined sex-specific age trends in muscle strength in order to identify potential trajectory patterns, and it showed that muscle strength tended to display similar age-related changes later in life regardless of the baseline level. Additionally, individuals in the low trajectory group had a higher mortality risk than did the high trajectory group [2]. However, reports examining longitudinal trajectories of muscle strength in patients on hemodialysis are limited, and their association with life prognosis remains unclear. Therefore, this study aimed to identify sex-specific aging patterns of handgrip strength as an indicator of muscle strength in patients on hemodialysis and to further investigate their association with life prognosis. Method Patients on hemodialysis with a minimum of two available measurements of handgrip strength between the years 2002 and 2022 were analyzed. In total, 544 patients (age: 65.1±11.9 years, 59.5% male, total observation data: 2,499) were enrolled in this study. Aging patterns of handgrip strength were classified by sex using group-based semiparametric mixture modeling. The association between typed aging patterns of handgrip strength and all-cause mortality was examined using Cox regression analysis after adjusting for the baseline age, body mass index, dialysis history, comorbidity index score, and hemoglobin and albumin levels. The statistical significance level was set at 5%. Results Age-related trajectory patterns of handgrip strength in men and women were categorized into three groups, low, middle, and high, as shown in Fig. 1. All three groups showed an age-related decline. The “low group” showed a reduction in handgrip strength (<28 kg for men and <18 kg for women) from baseline and continued to decline thereafter. The “middle group” did not show any decline at baseline, but decline was noted after 65 years of age. The “high group” displayed a decline in handgrip strength after 80 years of age, despite high handgrip strength at baseline. 23.9%, 60.1%, and 16.0% for men and 30.1%, 46.3%, and 23.7% for women were assigned to the low, middle, and high groups, respectively. When the high group was used as the reference group, the low groups showed a significantly higher mortality risk after adjusting for confounders in both men and women (men; p = 0.03, women; p<0.001). Conclusion In patients on hemodialysis, age-related decline of handgrip strength was observed in both men and women, regardless of baseline values. Among the three patterns of decline, the low group had a higher mortality rate compared to the high group in both men and women. The results suggest that even if decline in muscle weakness over time can be expected, handgrip strength needs to be improved in order to improve life prognosis.