A risk scoring system based on independent prognostic factors of mortality in patients with critical limb ischemia (CLI) shows good ability to predict 2-year life expectancy, according to a Japanese retrospective study published in the December 2014 issue of JACC: Cardiovascular Interventions. Use of the score may be helpful in identifying patients with poor prognosis who would be better candidates for endovascular therapy instead of bypass surgery.

For the study, Yoshimitsu Soga, MD, of Kokura Memorial Hospital (Kitakyushu, Japan), and colleagues analyzed data on 995 CLI patients who received endovascular therapy at 17 Japanese centers between March 2004 and December 2011. 

All patients received dual antiplatelet therapy before the procedure and lifelong aspirin and prolonged (at least 1 month) clopidogrel, ticlopidine, or cilostazol after the procedure.

At 2 years, 41% of patients died. Patients who died were older, less likely to be ambulatory, to have dyslipidemia, and to use statins, and more likely to require hemodialysis, to have cerebrovascular disease, and to be in a higher Rutherford class. 

Cardiovascular causes, including sudden death, were responsible for 47% of deaths, whereas noncardiovascular causes accounted for 46%. Infectious disease, including sepsis and pneumonia, was the predominant cause of noncardiovascular death. As the most common reasons for cardiac death were heart failure, acute MI, and ventricular fibrillation, the authors say this “suggests that the management of heart failure and prevention of ischemic cardiac events are important in CLI patients.”

On multivariate analysis, several factors were predictive of 2-year mortality (table 1).

Neither clinical procedural failure (P = .83) nor conversion to bypass after endovascular therapy (P = .62) was associated with 2-year life expectancy. 

Because no oral agents emerged as predictors of 2-year survival on multivariate analysis, the authors say that “the influence of medical therapy on CLI remains unclear.”

Risk Score Helps Predict Intermediate Mortality

A 2-year life expectancy risk score—where the higher the score, the less likely a patient will survive to 2 years—was calculated based on the results of the multivariate analysis shown in table 1. A score of 8 or greater, found in 31% of patients, corresponded with low 2-year survival. 

The authors say this is the first study to examine a 2-year life expectancy risk score for CLI that takes into account the multiple prognostic factors attributed to 2-year mortality. Additionally, they say this risk score could be used in choosing a treatment strategy for patients.

For example, “patients with scores ≥ 8 points have a [2-year life expectancy] < 50%, which suggests that [endovascular therapy] is preferable for revascularization [compared with bypass surgery] in these cases,” Dr. Soga and colleagues explain. However, they acknowledge that a “weak point” in the study—the aim of which was to aid in making the choice between bypass surgery and endovascular therapy—is that patients who underwent bypass surgery were not included in analysis. Also, there remains the possibility of selection bias. 

Variables Missing

In an editorial accompanying the study, Joshua A. Beckman, MD, MSc, and Mark A. Creager, MD, of Brigham and Women’s Hospital (Boston, MA), say that CLI sits at a “nexus of palliation and survival,” and as such, decisions regarding treatment must take into account more than just the elements included in the 2-year life expectancy score. 

Furthermore, the editorialists observe the lack of an area under the curve for each receiver-operating characteristic curve makes it difficult to compare the score with other risk assessment tools such as the BASIL, FINNVAS, and PREVENT models.

“Combining these datasets to generate a most accurate survival model would be helpful for physicians and surgeons who care for these patients,” they continue. 

Moreover, the medical and demographic factors included in this and other studies may not be enough, the editorialists explain. “Other important factors, such as nursing home residence, inability to leave the home, and dementia, are potent predictors of inability to ambulate after revascularization and should be incorporated into the decision-making analysis.”

1. Soga Y, Iida O, Takahaera M, et al. Two-year life expectancy in patients with critical limb ischemia. J Am Coll Cardiol Intv. 2014;7:1444-1449.

2. Beckman JA, Creager MA. Critical limb ischemia and intermediate-term survival [editorial]. J Am Coll Cardiol Intv. 2014;7:1450-1452.

Disclosures:

• Dr. Soga reports no relevant conflicts of interest.
• Dr. Becker reports being a consultant for AstraZeneca, Bristol-Myers Squibb, Novartis, and Merck. 
  
• Dr. Creager reports being a consultant for Aastrom Biosciences, AstraZeneca, and Novartis.

Related Stories:

• Endovascular Therapy Promising for Critical Limb Ischemia
• Drug-Eluting Balloon Fails for Below-the-Knee Lesions in Critical Limb Ischemia Patients 
  
• Infrapopliteal Angioplasty Shows Long-term Promise for Critical Limb Ischemia