Psoas muscle gauge and adverse clinical outcomes in patients on hemodialysis.

BACKGROUND

The relationship between the psoas muscle gauge (PMG), a combined sarcopenia indicator obtained from psoas muscle index (PMI) and psoas muscle density (PMD), and adverse clinical outcomes in patients on hemodialysis remains unclear. We examined whether psoas muscle gauge could predict all-cause mortality and new cardiovascular events more accurately than psoas muscle index in these patients.

METHODS

We retrospectively included 217 hemodialysis patients who underwent abdominal computed tomography. We calculated the psoas muscle gauge (arbitrary unit [AU]) at the fourth lumbar vertebra level as follows: PMI (cm/m) × PMD (Hounsfield units). We categorized the patients into higher and lower psoas muscle gauge groups based on sex-specific cutoffs obtained from the young Asian population. The outcomes were death and new cardiovascular events.

RESULTS

The psoas muscle gauge cutoffs were set at 231.1 and 328.8 AU in women and men, respectively. Eighty-five deaths and 95 new cardiovascular events occurred during the follow-up period of 4.4 (2.4-7.3) years. The 5-year survival rates were 59.2% and 94.9% in the lower and higher psoas muscle gauge groups, respectively (p < 0.0001). Moreover, after adjusting for sex and age, history of cardiovascular disease, C-reactive protein, modified creatinine index, and geriatric nutritional risk index, lower psoas muscle gauge was independently associated with increased all-cause death and new cardiovascular events (adjusted hazard ratio (aHR) 7.65; 95% confidence interval (CI) 2.37-24.66 and aHR 2.98; 95% CI 1.54-5.75, respectively). The concordance index (C-index) for predicting all-cause mortality and new cardiovascular events significantly improved when either psoas muscle index or psoas muscle gauge were added to the baseline risk model. Additionally, the C-index of the psoas muscle gauge-added model was significantly higher than that of the psoas muscle index-added model (0.815 vs. 0.784, p = 0.026) only when predicting all-cause mortality.

CONCLUSIONS

Psoas muscle gauge accurately predicted the risk of all-cause mortality and new cardiovascular events in patients undergoing hemodialysis. For predicting all-cause mortality, psoas muscle gauge may be recommended compared to psoas muscle index.