[Loss of weight in hemodialysis patients after hospitalization is related with length of stay and degree of inflammation].

Background: It is frequent to observe that hemodialysis patients suffer important loss of weight during hospital stay. This issue has not been investigated previously. Our aim in this study was to analyze factors associated with this loss of weight and what changes occur after admission in biochemical parameters with nutritional interest.

Patients And Methods: We retrospectively selected patients undergoing chronic hemodialysis who were admitted at hospital for acute or chronic pathologies, with a minimum length of stay of 4 days, taking only one episode of admission per patient. We chose loss of weight observed at hospital discharge, at 2 and 4 weeks later and we also collected routine laboratory data and adequacy parameters before and after the hospital admission and basic biochemical parameters in the first week of hospital stay.

Results: We included 77 patients, with 67±12 years and 30±34 months in dialysis. Forty (51.9%) were female (51.9%) and 22 diabetics (28.6%). Length of stay was 17.8±12.6 days (median 12). There were 70.4% patients who suffered a loss of weight at discharge and 81.4% at 4 weeks, without differences in sex or diabetes. Weight decreased significantly with a mean of -1.09 kg (95%CI -0.73 to -1.44). After 2 weeks the loss of weight was -1.64 kg (95%CI -1.21 a -2.07 kg) and after 4 weeks was -1.94 kg (95%CI -1.47 a -2.42 kg). Comparing parameters before and after admission, we observed a significantly decrease in serum urea levels (before 134±40 vs after 119±36 mg/dl; p= 0.001), creatinine (before 8.1±2.6 vs after 7.5±2.6 mg/dl; p < 0.001), phosphate (before 5.2±1.7 vs after 4.3±1.5 mg/dl; p < 0.001) and albumin (before 3.70±0.48 vs after 3.56±0.58 g/dl; p=0.05), without changes in adequacy parameters. Greater loss of weight at 4 weeks from discharge was correlated with larger length of stay (r= 0.41; p < 0.001), greater body mass index at admission (r= -0.23; p=0.05) and lower serum albumin at admission (r= 0.39; p= 0.012). It was also correlated with a lower serum albumin (r= 0.27; p=0.05), lower creatinine (r= 0.30; p= 0.02) and lower protein intake (nPNA) (r= 0.47; p= 0.002) after discharge. Lower serum albumin levels at admission were correlated with greater decreases of creatinine after discharge (r= 0.42; p= 0.009) and larger length of stay (r= -0.61; p < 0.001). Employing multivariate analysis we found that loss of weight was associated to length of stay and serum potassium levels before admission.

Conclusions: Hospitalization of hemodialysis patients have a negative nutritional impact causing a significant loss of weight, probably reflecting a reduction of muscle mass. We found that length of stay in hospital is a basic factor associated with this nutritional impairment. The pathologies promoting hospitalization could influence this derangement through inflammation but this hypothesis should be investigated.