Physical status and frailty index in nursing home residents : results from the INCUR study

AIM: The Short Physical Performance Battery (SPPB) is a widely used instrument for measuring physical performance, consisting of 3 sub-tests: a hierarchical test of balance, a gait speed test, and a chair stand test. Although equally considered in the computation of the SPPB score, each of the components may present a specific and different weight in clinical practice. The aim of this study was to estimate the relationship between SPPB and its component of an age-related deficit accumulation index (the so-called Frailty Index [FI] proposed by Rockwood). METHOD: Data are from a longitudinal cohort study (ie, the Incidence of pNeumonia and related ConseqUences in nursing home Residents [INCUR]) of 730 older persons (74.29% women) living in 13 French nursing homes. The FI was computed as the ratio between 30 actual and potential deficits the participant might have presented at the baseline visit (range between 0 [no deficit] and 1 [30 deficits]). Physical status was assessed using the SPPB score at baseline. Descriptive statistics and linear regression analyses were used to determine the relationship between the SPPB and FI and estimate which components of the SPPB were most strongly associated with the FI. RESULTS: Mean age of participants was 86.5 (SD 7.5) years, with a mean FI of 0.37 (SD 0.11) and SPPB of 2.5 (range between 0 and 12). The SPPB and its components were all significantly associated with the FI, but the magnitude of the associations varied. Linear regression analyses adjusted for age, sex, showed that the balance test [beta=-0.045 (95%CI -0.042; -0.028), p<0.0001] and chair stand test [beta=-0.040 (95%CI -0.054; -0.027), p<0.0001] was more strongly associated with the FI than the gait speed [beta=-0.015 (95%CI -0.021; -0.008), p<0.0001]. CONCLUSION: Of the 3 components of the SPPB, both balance and chair tests seem particularly relevant indicator of frailty among very old and complex elders living in nursing homes.