Vascular
Prospective decision analysis modeling indicates that clinical decisions in vascular surgery often fail to maximize patient expected utility

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Abstract

Background

Applied prospectively to patients with peripheral arterial disease, individualized decision analysis has the potential to improve the surgeon’s ability to optimize patient outcome.

Methods

A prospective, randomized trial comparing Markov surgical decision analysis to standard decision-making was performed in 206 patients with symptomatic lower extremity arterial disease. Utility assessment and quality of life were determined from individual patients prior to treatment. Vascular surgeons provided estimates of probability of treatment outcome, intended and actual treatment plans, and assessment of comfort with the decision (PDPI). Treatment plans and PDPI evaluations were repeated after each surgeon was made aware of model predictions for half of the patients in a randomized manner.

Results

Optimal treatments predicted by decision analysis differed significantly from the surgeon’s initial plan and consisted of bypass for 30 versus 29%, respectively, angioplasty for 28 versus 11%, amputation for 31 versus 6%, and medical management for 34 versus 54% (agreement 50%, kappa 0.28). Surgeon awareness of the decision model results did not alter the verbalized final plan, but did trend toward less frequent use of bypass. Patients for whom the model agreed with the surgeon’s initial plan were less likely to undergo bypass (13 versus 30%, P < 0.01). Greater surgeon comfort was present when the initial plan and model agreed (PDPI score 47.5 versus 45.6, P < 0.005).

Conclusions

Individualized application of a decision model to patients with peripheral arterial disease suggests that arterial bypass is frequently recommended even when it may not maximize patient expected utility.

Introduction

Successful long-term functional limb salvage in patients with peripheral vascular reconstruction is limited by graft occlusion, progressive compromise of distal arterial outflow, and wound problems, infection, or extensive gangrene that mandate amputation despite a patent graft 1, 2, 3. Patients with chronic lower extremity vascular disease who are initially ambulatory do well with operative bypass, but less than a quarter who are nonambulatory prior to surgery become ambulatory 4, 5. Due to these and other factors, decision-making for individual patients with chronic peripheral vascular occlusive disease can be quite complex. The current standard of practice is for surgeons to advise patients based on objective reports of the risks and benefits of intervention in conjunction with subjective assessment of the patient’s needs. As a result, the decision to intervene can be complicated by unrealistic expectations by the patient and improper interpretation and application of the available data by the surgeon.

Decision analysis represents one set of tools developed by health-care researchers to evaluate complex medical decisions 6, 7, 8, 9. It has typically involved large populations of patients analyzed in a retrospective manner. However, attempts to apply such processes to individual patients have been difficult due to the high degree of variability in individual patient outcome probabilities and values 10, 11. We have previously examined the use of individualized decision analysis in patients with chronic peripheral vascular occlusive disease [12]. One important limitation of that study was that the population was limited to patients already scheduled to undergo bypass operation. Among this group, the chance of a favorable long-term outcome was much greater (84% good outcome) when the decision analysis model agreed with bypass as the best therapy compared with when the decision analysis model predicted that either medical therapy or primary amputation would be preferable (50% good outcome). In this way, surgical decision analysis identified a subgroup of patients with chronic lower extremity ischemia who were less likely to benefit from bypass operation, with the implication that these patients might do better with another form of intervention. However, that investigation did not go far enough. It excluded from evaluation medically managed patients with potentially lesser degrees of ischemia and others with more advanced disease who had been advised to undergo primary amputation. Equally as important, the impact of newer endovascular methods for revascularization was not considered in the analysis. Therefore, the current study was designed to test the hypothesis that Markov surgical decision analysis can improve the surgeon’s ability to make the appropriate decision for a wide range of management options for patients with a broader spectrum of severity of peripheral vascular occlusive disease of the lower extremities.

Section snippets

Study entry

All patients undergoing elective lower extremity bypass operation at the Medical University of South Carolina and Ralph H. Johnson Department of Veterans Affairs Medical Center over a 28-month period were screened for participation in this randomized, prospective study. Inclusion criteria included the presence of symptomatic infrainguinal arterial occlusive disease as manifested by intermittent claudication, resting ischemia pain, or ischemic tissue loss with ulcers or gangrene. Exclusion

Results

From July 1999 through November 2001, 214 patients were screened; 208 were consented, and 206 were enrolled with data available. Demographic data, most severe qualifying symptom, surgical history, and duration of follow-up for the 100 patients randomized to the SA group and the 106 patients randomized to the SU groups are included in Table 1.

Values for the utility score were related to how it was assessed, with visual analogue scale values consistently lower than those obtained using time

Discussion

Peripheral bypass operation has increasingly been evaluated according to its impact on patient functional status and quality of life 4, 15, 16, 17, 18. Several reports have demonstrated improvement in global patient health following lower extremity bypass superior to that experienced after primary amputation 19, 20, 21, 22, 23, 24, 25, 26. However, a few investigators have emphasized that a significant improvement in the clinical indicators of lower limb ischemia cannot be assumed to impart a

Uncited references

This section comprises references that occur in the reference list but not in the body of the text. Please position each reference in the text or delete it. Any references not dealt with will be retained in this section: [26].

Acknowledgements

This work was supported by an Established Investigator Award of the American Heart Association and by the Office of Research and Development, Medical Research Service, Department of Veterans Affairs.

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