Validation of the Pittsburgh Performance Fatigability Index in the Study of Muscle, Mobility and Aging (SOMMA) 2023 Qiao et al

Abstract

Background
The Pittsburgh Performance Fatigability Index (PPFI) quantifies the percent decline in cadence using accelerometry during standardized walking tasks. Although PPFI has showed strong correlations with physical performance measures, the developmental sample was relatively homogenous and small, necessitating further validation.

Methods
Participants from the Study of Muscle, Mobility and Aging (N=805, age=76.4±5.0 years, 58% women, 85% white) wore an ActiGraph GT9X on non-dominant wrist during usual-paced 400m walk. Tri-axial accelerations were analyzed to compute PPFI (higher score=greater fatigability). To evaluate construct and discriminant validity, Spearman correlations (rs) between PPFI and gait speed, Short Physical Performance Battery (SPPB), chair stand speed, leg peak power, VO2peak, perceived fatigability and mood were examined. Sex-specific PPFI cut-points that optimally discriminated gait speed using classification and regression tree were then generated, as well as their discriminate power in relation to aforementioned physical performance and perceived fatigability metrics.

Results
Median PPFI scores were 1.4% (range: 0%-21.7%), higher among women than men (P<0.001). PPFI score was moderate-to-strongly correlated with gait speed (rs=-0.75), SPPB (rs=-0.38), chair stand speed (rs=-0.36), leg peak power (rs=-0.34) and VO2peak (rs=-0.40), and less strongly with perceived fatigability (rs=0.28-0.29), all P<0.001. PPFI score was not correlated with mood (|rs|<0.08). Sex-specific PPFI cut-points [no performance fatigability: PPFI=0%; mild performance fatigability: 0%<PPFI<3.5% (women), 0%<PPFI<5.4% (men); moderate-to-severe performance fatigability: PPFI≥3.5% (women), PPFI≥5.4% (men)] discriminated physical performance (all P<0.001), adjusted for demographics and smoking status.

Conclusion
Our work underscores the utility of PPFI as a valid measure to quantify performance fatigability in future longitudinal epidemiologic studies and clinical/pharmaceutical trials.

Paywall, https://academic.oup.com/biomedgero...e-abstract/doi/10.1093/gerona/glad197/7241400

 

See also this thread, Validation of the Pittsburgh Fatigability Scale in a mixed sample of adults with and without chronic conditions, 2019, Carlozzi et al