Background
The Malnutrition-Inflammation Score (MIS), a non-expensive and easy-to-assess score between 0 and 30 to examine protein-energy wasting (PEW) and inflammation, includes 7 components of the subjective global assessment, body mass index, and serum albumin and transferrin concentrations. We hypothesized that the MIS risk-stratification of chronic hemodialysis (HD) patients in predicting outcomes is better than its components or laboratory markers of inflammation.
Study Design
5-year cohort study.
Setting & Participants
We examined 809 stable HD outpatients and followed them for up to 5 years (10/2001–12/2006).
Predictors
MIS and other nutritional and inflammatory markers.
Outcomes & Measurements
Prospective all-cause mortality, health-related quality of life via SF-36, and tests of body composition.
Results
The MIS was correlated with serum interleukin-6 (IL-6) (r=+0.26, p<0.001), C-reactive protein (CRP) (r=+0.16, p<0.001) and several measures of nutritional status. Patients with higher MIS had lower SF-36 scores. After multivariate adjustment for case-mix and other measures of PEW, the chronic HD patients in the second (3–4), third (5–7) and fourth (≥8) quartiles of MIS had worse survival rates than those in the first (0–2) quartile (p<0.001). Each 2 unit increase in MIS was associated with two-fold higher death risk, i.e., adjusted death hazard ratio of 2.03 (95% CI: 1.76–2.33, p<0.001). Cubic spline survival models confirmed linear trends. The areas under the receiver operating characteristic curves for the continuum of MIS in predicting 5-year mortality (0.67) was equal to IL-6 (0.67) and somewhat better than CRP (0.63).
Limitations
Selection bias and unknown confounders.
Conclusions
In chronic HD patients, the MIS is associated with inflammation, nutritional status, quality of life, and 5-year prospective mortality. The mortality-predictability of the MIS appears equal to serum IL-6 and somewhat greater than CRP. Controlled trials are warranted to examine whether interventions to improve MIS can also improve clinical outcomes in chronic HD patients.
Physical inactivity is associated with increased mortality in CKD and non-CKD populations. As in the non-CKD population, increased physical activity might have a survival benefit in the CKD population.
Serum transferrin, estimated by total iron-binding capacity (TIBC), may be a marker of protein-energy wasting (PEW) in maintenance hemodialysis (MHD) patients. We hypothesized that low TIBC or its fall over time is associated with poor clinical outcomes. In 807 MHD patients in a prospective 5-year cohort, associations of TIBC and its changes over time with outcomes were examined after adjustment for case-mix and markers of iron stores and malnutrition-inflammation including serum interleukin-6, iron and ferritin. Patients with serum TIBC ≥250 mg/dl had higher body mass index, triceps and biceps skinfolds and mid-arm muscle circumference and higher serum levels of iron but lower ferritin and inflammatory markers. Some SF-36 quality of life (QoL) components were worse in the lowest and/or highest TIBC groups. Mortality was incrementally higher in lower TIBC levels (p-trend <0.001). Adjusted death hazard ratio was 1.75 (95% CI: 1.00–3.05, p = 0.05) for TIBC <150 compared to TIBC of 200–250 mg/dl. A fall in TIBC >20 mg/dl over 6 months was associated with a death hazard ratio of 1.57 (95% CI: 1.04–2.36, p = 0.03) compared to the stable TIBC group. Hence, low baseline serum TIBC is associated with iron deficiency, PEW, inflammation, poor QoL and mortality, and its decline over time is independently associated with increased death risk.
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