The effects of body mass index on peak seat-interface pressure of institutionalized elderly

Objective: To deter-mine if body mass index (BMI) influenced seat-interface pressure in a population of institutionalized elderly. Design: A cross-sectional comparison of peak seat-interface pressure in 4 groups of institutionalized elderly was compared with BMI scores defined as either thin (<20kg/m(2)), desirable range (20-24.9kg/m(2)), grade I obesity (25-29.9kg/m(2)), or grade IT obesity (30-40kg/m(2)). Setting: Several small nursing homes and a university in a small urban community. Participants: A convenience sample of 75 individuals (age range, 65-95y) living in 1 of 3 skilled nursing facilities. Interventions: Not applicable. Main Outcome Measures: The Novel Pliance(TM) seat pressure-mapping system was used to collect seat-interface pressure data. Each participant was asked to sit in the wheelchair for up to 10 minutes while the seat-interface pressures were recorded. Body weight and height of each participant were obtained from the medical chart; these characteristics were then used to calculate a BMI for each participant. Results: A 1-way analysis of variance on the peak seat-interface pressures revealed significant differences between the 4 groups (P<.05). Post hoc comparisons showed differences in peak seat-interface pressure between the thin and desirable range groups (P<.05), the thin and grade I obesity group (P<.05), and the thin and grade IT obesity groups (P<.05). Differences in peak seat-interface pressure decreased as BMI increased. Conclusions: The results are consistent with the results of a previous study of individuals with spinal cord injuries. In the current study, peak seat-interface pressure was highest in the thin elderly group, which had the lowest BMI levels of any of the 4 groups. Differences in the peak seat-interface pressures were less as BMI increased.