Variation in clinical decision making is a partial explanation for geographical variation in lower extremity amputation rates

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Abstract
Background: Rates of lower extremity amputation vary significantly both between and within countries. The variation does not appear to support differences in need as an explanation. This study set out to see if variations in clinical decision making might contribute to the explanation. Methods: Based on an extensive audit database of lower extremity amputations and revascularization operations, a decision model was produced. Drawing on items in this model allowed the selection of six clinical cases that differed in their probability of having amputation as the outcome. Two cases had 80 per cent or more, two cases had 45–55 per cent and two cases had 20 per cent or less probability of amputation. Each of ten consultant vascular surgeons looked at these cases without knowledge of their probability of outcome and decided on amputation or revascularization. Results: Overall the chance-adjusted level of agreement (kappa coefficient) between the decisions made by ten surgeons on the six clinical cases and the actual outcome was 0·46, indicating a moderate level of agreement. The kappa coefficient for individual surgeons showed complete agreement (κ = 1) for four, substantial agreement (κ = 0·66) for four, fair agreement (κ = 0·32) for one and no agreement other than at a chance level (κ = 0) for one surgeon. Conclusion: Variations in the clinical decisions made by vascular surgeons given the same patient are likely to explain at least a part of the observed geographical variation in rates of lower extremity amputation. Consensus guidelines may enable more consistent decision making for this problem.