Which is a Better Measure of Frailty in Perioperative Setting: Deficit Accumulation Model or Phenotype Model?

Though most physicians believe they can identify frail patients, frailty is a poorly characterized and complex clinical syndrome. Frailty has been categorized four dimensions by de Vries et al: 1) physical (physical activity, nutrition, mobility, strength and energy); 2) biochemical (nutritional and inflammatory biomarkers); 3) psychological (cognition and mood); and, 4) social (social contact and support). 1 However, the pathophysiology of frailty remains unclear. Two broad hypotheses have been proposed.

Deficit accumulation model: This hypothesis assumes that frailty occurs due to accumulation and additive effect of multiple deficits, which occur across various domains. The more deficits a person has, the more likely that person is to be frail. Frailty in this paradigm is thus measured by identifying the number of positive factors/ deficits from a list. This is used to create a proportional index of deficits, expressed as the ratio of deficits present to the total number of deficits considered.

Many studies have used a modified frailty index (MFI) with 11 factors, which has shown to correlate well with patient outcomes after surgery.

Phenotype model: Fried et al in 2001 proposed a phenotype based model, in which she identified various clinical features that define frailty as a clinical syndrome. This criterion, known as Fried index, consists of 5 factors- shrinking, weakness, exhaustion, slowness, and low physical activity level. The Fried index is the most commonly used phenotype-based assessment tool to evaluate frailty. An advantage is its ease-of use during preoperative visits. Measurement of these factors in a perioperative setting was further characterized by Makary et al in 2010, and was the basis for the Hopkins Frailty Score (HFS).

Currently, there exists no gold standard for assessment of frailty, especially in the perioperative setting. In the absence of a well-accepted gold standard, a measurement of frailty which would predict adverse postoperative outcomes would be useful. However, no study has compared the prognostic abilities of HFS and MFI, after non-cardiac surgery.

All adult patients presenting to pre anesthesia evaluation clinic (PACE) at Cleveland Clinic main campus will be included in the this prospective observational cohort study. Frailty would be evaluated prospectively using HFS and components of MFI will be obtained from Cleveland Clinic Perioperative Health Documentation System registry (PHDS).