Mean Percent Weight Change Research Articles

Association of Weight Status With Urinary Tract Infections in Nursing Home Residents

Poor weight status in nursing home residents is associated with increased morbidity, mortality and costs. Aggressive nutrition therapy may remediate the abnormality if inadequate nutrition is the primary cause, but may be futile if progressive disease is the primary cause. A pilot study examined factors associated with weight change over three months in newly admitted undernourished patients (n=43). Absence of urinary tract infection (UTI) was significantly (p<.05) associated with weight gain in both males (r=.45) and females (r=.63). To further explore this relationship the weight status of 78 nursing home residents (63 females, and 16 males) who had contracted at least 1 UTI was monitored over a six-month period using medical record data. Females with 3 or more UTIs on average lost weight, whereas those with only 1 UTI did not. Mean percent weight change ±std.dev. in females in the 3+UTI group was −3.5±6.8%, and was significantly different (t-test, p<.03) than that of the 1 UTI group which was +0.4±3.8%. No significant associations with frequency of UTI were found with percent change of weight in men or with final body mass index in either gender.

Experimental and Field Evidence for Inter- and Intraspecific Competition in Two Freshwater Fishes

Direct evidence for intra- and interspecific competition in fishes was obtained by manipulating populations of yellow perch (Perca flavescens) and pumpkinseed (Lepomis gibbosus) stocked into littoral zone enclosures. Stocking densities were above, below, and equal to measured littoral zone fish biomass. There were no significant differences in mean percent weight change at given densities among repeated experiments (each of 14-d duration). In experiments testing for intraspecific competition, all fish reared at low density gained weight, all fish reared at high density lost weight, and mean weight change at natural density did not differ from 0.0. In experiments testing for interspecific competition, growth of pumpkinseed did not differ from growth of pumpkinseed reared alone at equivalent densities whereas growth of yellow perch was depressed relative to growth of yellow perch reared alone at equivalent densities. These growth changes did not result from behavioural interactions. We conclude that (a) inter- and intraspecific competition for food is significant at natural fish densities and (b) pumpkinseed are superior to perch when competing for food. A marked reduction in yellow perch growth in Lake Memphremagog between 1972 and 1983, coincident with a major increase in pumpkinseed abundance, is consistent with these findings and our interpretations.