RESUMEN
Serum homocysteine levels, which increase with age, are now recognized as a vascular risk factor and are related to the development of heart failure and dementia in the elderly. However, relatively low serum homocysteine levels have also been reported to be an adverse prognostic factor in dialysis patients. The objective of the study was to analyze the prevalence, clinical significance, and prognostic value of serum homocysteine levels in patients older than 65 years, admitted to a general internal medicine hospitalization unit. We studied 337 hospitalized patients, 184 males and 153 females, aged 77.2+/-0.4 years, whose admission was not determined by an acute vascular event. We recorded past vascular events and vascular risk factors. We determined the body mass index (weight in kilograms divided by the square of height in meters), and cholesterol, triglyceride, folate, vitamin B12, and homocysteine levels. We also studied 36 control subjects (18 males and 18 females) of similar age. After discharge, we assessed the survival status of 301 patients by telephone recall. Survival curves were plotted by the method of Kaplan and Meier. Median survival was 1186 days. The 15th (9.6 micromol/L) and 50th (14.4 micromol/L) percentiles, as the lowest and highest cut-off points, were empirically defined as those related to a shorter survival. Serum homocysteine concentration was significantly positively correlated with age and serum creatinine and albumin concentrations, and negatively correlated with serum cobalamin and folate concentrations. The average serum homocysteine concentration for the patients group, as a whole, was 16.5+/-0.5 micromol/L, not significantly different from the control group, but with a much greater dispersion, as patients with congestive heart failure or cognitive impairment had higher serum homocysteine concentrations, and patients with sepsis, leukocytosis, and hypoalbuminemia had lower concentrations. Malnutrition was associated both with abnormally high and low homocysteine concentrations, and abnormally low and abnormally high homocysteine concentrations were both associated with higher mortality. In conclusion, low homocysteine levels in elderly non-vitamin-supplemented hospitalized patients should not be interpreted as a protective factor in some individuals. Instead, it may be considered as an effect of an inflammatory-malnutrition process associated with a poor prognosis.