We would like to congratulate Kim and colleagues for their interesting review focusing on pre-operative frailty assessment in predicting cardiosurgical outcomes. The above authors performed a meticulous analysis of the literature, confirming the feasibility and validity of frailty-available instruments.
We are currently performing a prospective study on the same topic, but limiting our analysis to urological patients. Comparing the findings of these two surgical fields may help our understanding of “how and why” to appraise frailty.
As stressed by the above authors, we found very many frailty instruments available. In our prospective study, until now we have evaluated 78 elderly (≥70 years) patients, subjected to major urological (both endoscopic and surgical) procedures, according to Edmonton Frail Scale (EFS) criteria(1), all the components of PACE(2), addicting Charlson Morbidities Index, and some biochemical parameters (e.g., albumin, hemoglobin). We found that some domains evaluating social support, nutritional status and physical performance were powerful aspects in predicting post-operative 30-day complications (Grade ≥2 according to the Clavien-Dindo classification).
Interestingly, although only a few reports contain analyses of biochemical parameters(3), in our study we demonstrated the role of albumin in predicting poor outcomes: the reasons for this are not only due to nutritional status, but also to the fact that low albumin seems to be related to general inflammation or stress and may be an indicator of a patient’s vulnerability.
For all the above reasons, we agree with the above authors in confirming that, in our experience, multi-component frailty instruments can provide better risk discrimination than single-component ones. Frailty is confirmed to be essential in pre-operative evaluations of older patients although, as most notably reported by Makary et al.(4), any degree of pre-operative frailty is predictive of post-operative complications, but currently available evidence is too inconsistent to guide clinical decision-making.
Starting from the conclusions of Kim et al. emphasizing that criteria should be established for selecting which domains should be measured, we suggest that large, well-designed, clinical studies specifically focusing on single specialties will be needed to select the most accurate predictive parameters and consequently to develop targeted risk-reduction strategies for frail older surgical patients.
We conclude by stressing that, in oncological fields, frailty assessment can efficiently predict outcomes in older patients, with the result that its influence on survival is comparable with that of TNM staging(5).

References
1. Rolfson DB, Majumdar SR, Tsuyuki RT, Tahir A, Rockwood K. Validity and reliability of the Edmonton Frail Scale. Age Ageing 2006;35:526-9.

2. Pope D, Ramesh H, Gennari R, et al. Pre-operative assessment of cancer in the elderly (PACE): a comprehensive assessment of underlying characteristics of elderly cancer patients prior to elective surgery. Surg Oncol 2006;15:189-97.

3. Gibbs J, Cull W, Henderson W, Daley J, Hur K, Khuri SF. Preoperative serum albumin level as a predictor of operative mortality and morbidity: results from the national VA surgical risk study. Arch Surg 1999;134:36-42.

4. Makary MA, Segev DL, Pronovost PJ, et al. Frailty as a predictor of surgical outcomes in older patients. J Amer Coll Surg 2010;210:901-8.

5. Ommundsen N, Wyller TB, Nesbakken A, et al. Frailty is an independent predictor of survival in older patients with colorectal cancer. Oncologist 2014. pii: theoncologist.2014-0237.