Serum β-2 Microglobulin Levels Predict Mortality in Dialysis Patients

Abstract

In the randomized Hemodialysis (HEMO) Study, chronic high-flux dialysis, as defined by higher beta-2 microglobulin (beta(2)M) clearance, compared with low-flux dialysis did not significantly alter all-cause mortality in the entire cohort but was associated with lower mortality in long-term dialysis patients. This analysis examined the determinants of serum beta(2)M levels and the associations of serum beta(2)M levels or dialyzer beta(2)M clearance with mortality. In a multivariable regression model that examined 1704 patients, baseline residual kidney urea clearance and dialyzer beta(2)M clearance were strong predictors of predialysis serum beta(2)M levels at 1 mo of follow-up, with regression coefficients of -7.21 (+/-0.69 SE) mg/L per ml/min per 35 L urea volume (P < 0.0001) and -1.94 (+/-0.30) mg/L per ml/min (P < 0.0001),respectively. In addition, black race and baseline years on dialysis correlated positively whereas age, diabetes, serum albumin, and body mass index correlated negatively with serum beta(2)M levels (P < 0.05). In time-dependent Cox regression models, mean cumulative predialysis serum beta(2)M levels but not dialyzer beta(2)M clearance were associated with all-cause mortality (relative risk = 1.11 per 10-mg/L increase in beta(2)M level; 95% confidence interval 1.05 to 1.19; P = 0.001), after adjustment for residual kidney urea clearance and number of prestudy years on dialysis. This association is supportive of the potential value of beta(2)M as a marker to guide chronic hemodialysis therapy.

Differences in associated factors between aortic and mitral valve calcification in hemodialysis

“…18 In patients on HD, serum b 2 M is markedly increased and predicts all-cause mortality, 19,20 but studies on the relationship between serum b 2 M and cardiovascular disease are limited. It has been reported that serum b 2 M correlates with carotid IMT 21 and the number of calcified valves.…”

Association between Serum β2-Microglobulin Level and Infectious Mortality in Hemodialysis Patients

“…In the HEMO Study, membrane flux was defined by the clearance of ␤ 2 M, taken as a surrogate for the clearance of middle molecules. As a result of the higher clearance, the cumulative mean predialysis serum ␤ 2 M level during follow-up in the high-flux arm was statistically significantly lower than that in the low-flux arms (33.6 versus 41.5 mg/L) (5). Further secondary analysis of the data showed that predialysis serum ␤ 2 M levels predicted allcause mortality in the HEMO Study cohort, with an 11% increase in mortality for each 10-mg/L increase in ␤ 2 M level, even after adjustment for years on dialysis and residual kidney function (5).…”

“…The dialyzers used, frequency of serum sample collection for ␤ 2 M, and calculation of clearances and Kt/V of ␤ 2 M in the HEMO Study were previously reported (2,5,10). The criteria for high-flux dialyzers were an ultrafiltration coefficient Ն14 ml/h per mmHg and a ␤ 2 M clearance Ͼ20 ml/min averaged over the lifespan of the dialyzer during clinical dialysis.…”

“…Dialyzer clearance of ␤ 2 M was calculated on the basis of the change in serum ␤ 2 M concentration during the dialysis session as described previously (2,5,10,11). The Kt/V for ␤ 2 M was calculated by multiplying the dialyzer ␤ 2 M clearance by the treatment time and dividing the product by the postdialysis extracellular fluid volume, which was calculated as one third of the urea distribution volume estimated by urea kinetics.…”

“…To avoid confounding from various reuse limits of different dialyzer/reprocessing method combinations, dialyzer ␤ 2 M clearance and ␤ 2 M Kt/V for different dialyzer/reprocessing method combinations were based on averages of predicted values at each follow-up kinetic modeling session (5). The predicted dialyzer ␤ 2 M clearance and ␤ 2 M Kt/V were obtained by multiple regression analysis of the observed values on the type of dialyzer, reuse number, and type of reprocessing method, based on sessions in which the serum ␤ 2 M levels were measured.…”