Low serum concentration of obestatin as a predictor of mortality in maintenance hemodialysis patients.

Obestatin, a proposed anorexigenic gut hormone, has been shown to have a number of beneficial cardiotropic effects in experimental studies. We hypothesized that obestatin alteration in hemodialysis patients may link to clinical outcomes. This cross-sectional study with prospective followup for almost 4 years was performed on 94 prevalent hemodialysis patients. Obestatin, leptin, proinflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-6, and various nutritional markers were measured. Patients with low obestatin levels, defined as a level less than median, had a worse all-cause mortality and cardiovascular mortality. The crude all-cause (HR 2.23, 95% CI 1.17 to 4.24) and cardiovascular mortality hazard ratios (HR 4.03, 95% CI 1.27 to 12.76) in these patients continued to be significant after adjustment for various confounders for all-cause mortality. Across the four obestatin-TNF-α categories, the group with low obestatin and high TNF-α (above median level) exhibited a worse outcome in both all-cause mortality and cardiovascular mortality. Clinical characteristics of patients in low obestatin high TNF-α group did not differ from other obestatin-TNF-α categorized groups. In summary, low serum obestatin concentration is an independent predictor of mortality in prevalent hemodialysis patients. Novel interactions were observed between obestatin and TNF-α, which were associated with mortality risk, especially those due to cardiovascular causes.