*189. Specific Activity Scale, A Predictor of Peak VO2 in Heart Failure
T Corvera-Tindel, Greater Los Angeles VAMC/UCLA School of Nursing; LV Doering, School of Nursing; K Machuca, Greater Los Angeles VAMC; T Gomez, Greater Los Angeles VAMC
Objectives: Peak oxygen consumption (VO2) is an objective measure of functional capacity and predicts morbidity and mortality in heart failure (HF) patients. However, it is too expensive, time consuming, and high-risk for frequent clinical use. The ideal surrogate measure of peak VO2 would be cost-effective, brief, and safe. Accordingly, we evaluated the relationship of peak VO2 to 4 self-report questionnaires purported to measure functional capacity: Specific Activity Scale (SAS), Heart Failure Function Status Inventory (HFFSI), Dyspnea-Fatigue Index (DFI), and Cardiac Quality of Life Index (CQLI).
Methods: In 24 HF patients, NYHA Class II-III (age 63.0 +/- 8.9 years, LVEF .27 +/- .85, peak VO2 13.4 +/- 3.1 ml/kg/min, 100% male), we analyzed bivariate correlations of peak VO2 with questionnaire scores and clinical factors identified as intervening variables. Multiple linear regression, with entry criterion of bivariate significance </= .10, was used. To control for their effects, significant clinical factors were entered first as a block, followed by questionnaire scores.
Results: Clinical factors correlated with peak VO2 were smoking pack/years (r = .31, p = .07) and heart rate variability (r = .40, p = .03). All 4 self-report instruments were correlated with peak VO2: SAS (r = -.51, p = .006), HFFSI (r = .50, p = .006), DFI (r = .39, p = .03), and CQLI(r = .33, p = .06). However, in multivariate analysis, only SAS, accounting for 23% of the variance, was an independent predictor of peak VO2 (p = .01).
Conclusions: SAS, a 4-item self-report questionnaire, is highly predictive of peak VO2 in HF patients.
Impact: For use after initial exercise testing, SAS holds promise as a surrogate for follow-up VO2 measurement and for trending functional capacity. Since SAS is simple to use, efficient, and inexpensive, its use in HF patients as a proxy for peak VO2 merits further study.