Irrational Responses to Risk Preference Questionnaires by Patients with Diabetes with or without Retinopathy and Comparison with Those without Diabetes

Abstract

Purpose: The risk preferences of patients with diabetes have profound effects on the progression of complications. The present study aimed to clarify whether the preferences of patients with diabetes and retinopathy are deliberately risk-seeking or irrational and whether this propensity is specific to those with retinopathy or is also found in patients without retinopathy compared with those without diabetes.

Patients and methods: A total of 394 patients with diabetes (264 without retinopathy and 130 with retinopathy) and 198 patients without diabetes agreed to participate in this survey. The questions were modified versions of those from the Japan Household Survey on Consumer Preferences and Satisfaction, which sought to determine the participants' personal socioeconomic status and risk preferences. In the questionnaires, responses were analyzed by determining the participants' willingness to pay for a lottery ticket and for an insurance policy. Irrational responses were defined as violations of two axioms of the Expected Utility Theory: completeness and transitivity.

Results: The incidence of irrational responses increased with age and was associated with educational level. The incidence of irrational responses was significantly higher in patients with retinopathy than in those without retinopathy after adjusting for age and educational level. There was no significant difference in the incidence of irrational responses between patients with diabetes but without retinopathy and those without diabetes.

Conclusion: The risk-seeking behavior of patients with diabetes and retinopathy was not deliberate but was irrational under uncertainty. Medical professionals should be aware of their patients' propensity to make irrational decisions, which is an important risk factor for the progression of retinopathy in patients with diabetes regardless of age and educational level.

Keywords: behavioral economics; cognitive function; educational level; expected utility theory.

Figure 1

Recruitment process.

Figure 2

(Continued).

Figure 2

(A) Questionnaire format for questions 12 and 13. (B) Examples of rational and irrational responses to questions 12 and 13. The circles indicate patients’ choices. Criteria for the rational choices according to the two axioms of the expected utility theory. Axiom 1, completeness: all prices should be chosen, either “Purchase” or “Do not purchase.” Axiom 2, transitivity: the choices for prices lower than the maximum “Purchase” price should be “Purchase.” Rational choices must meet both axioms 1 and 2. Violations of the two axioms are considered as irrational.