Functional capacity assessment and Minimal Clinically Important Difference in post-acute cardiac patients: the role of Short Physical Performance Battery.

Background: The Short Physical Performance Battery (SPPB) test is a well-established tool to assess physical performance, and to identify frail patients. Assessment of the SPPB in a specific population of elder patients in cardiac rehabilitation phase after a cardiac event is missing.

Aim: The aim of this study was to correlate SPPB and the cardiac rehabilitation outcome in a group of elder patients after a cardiac event and to identify the Minimal Clinically Important Difference (MCID) of the SPPB.

Methods: Consecutive (n = 392) patients aged ≥75 years, in the rehabilitation phase after cardiac surgery (70.1%), congestive heart failure (7.4%), or acute coronary syndrome (22.5%), were enrolled. SPPB was performed twice: on admission and discharge. The MCID was assessed with the 'anchor method', and the Patient Global Impression of Change was employed as the anchor.

Results: On admission, SPPB classified 56, 117, 116, and 94 patients as severe, moderate, mild, or minimal/no limitations, respectively. Patients with the lower SPPB had the longer length of stay, and the higher complications rate. At receiver operating characteristic analysis, an SPPB improvement >1 was identified as the MCID (area-under-curve 0.77, 95% CI 0.67-0.85). Overall, 285 patients (74.2%) had a 'clinically significant' improvement in SPPB, with a rate of improvement higher in patients with severe/moderate limitations (83.0%) and lower in those with mild (78.9%) or minimal/no limitations (53.6%).

Conclusion: A lower SPPB score is associated with a higher complications rate in the post-acute phase. An improvement >1 point of SPPB was identified as the MCID; this reference value could serve as the goal for rehabilitation interventions.