Association between phase angle and level of independence in daily living among institutionalized super older females requiring nursing care

[Purpose] This study aimed to clarify the association between phase angle (PhA) and the level of independence in daily living among institutionalized super older females requiring nursing care. [Participants and Methods] This three-facility cross-sectional study enrolled 173 nursing home residents (mean age 91.0 years, standard deviation 4.9 years) divided into five groups, from 80+ to 100+ years of age, in 5-year increments. PhA, skeletal muscle mass index, body fat percentage, body mass index, and Barthel Index were measured in the five groups. We measured the relationship between age and PhA and analyzed partial correlation coefficients using these items. The adjusted variables differed significantly among the five groups. [Results] The overall PhA was 2.91 degrees, with a 2.36-degree PhA in patients aged >100 years. Age differences were found between the PhA and the Barthel Index. A significant correlation (0.66) was identified between the PhA and the Barthel Index. The age-adjusted partial correlation coefficient between the PhA and the Barthel Index was 0.56, indicating a moderately significant positive correlation. [Conclusion] This study identified an association between PhA and independence in daily living among female nursing home residents aged 80–107 years, indicating that the PhA is an excellent indicator of physical condition.