How Walking Programs’ Characteristics Affect Economic Efficiency of Lifestyle Interventions

Background and Objective: A lifestyle intervention, including walking programs, is expected to prevent many chronic diseases, e.g., type 2 diabetes focused in our study. Our primary objective is to examine how specific characteristics of walking programs (i.e., types of a walking partner and cash incentive to compensate for the lower utility due to walking with a formal organized group) affect the economic efficiency of such lifestyle interventions from the societal perspective. Our secondary objective is to estimate how the intervention’s economic efficiency will change when incorporating the potential positive spillover impact on an “informal” walking partner (e.g., an intervention participant’s friend or neighbor).

Methods: We developed a decision model to estimate cost-effectiveness of a lifestyle intervention among a hypothetical prediabetes adult cohort in the U.S., based on the literature particularly studies about the Diabetes Prevention Program (DPP), over ten years. During the first three years, the intervention participants are recommended to walk with a formal organized group. Conducting a conjoint analysis, Brown and associates (2009) estimated that a cash incentive of $43 is needed to offset utility loss due to walking with a formal organized group for 150 minutes per week (i.e., $2,240 per year), compared to an “informal” walking partner. We assumed that 50% of participants, who dropped out during year 1, would have continued to enroll in the intervention if they either received the cash incentive or walked with an informal walking partner (who is assumed to be paid by the intervention program at the hourly rate of a minimum wage ($7.25) or a median wage ($17.81)). Additionally, if an informal walking partner is also prediabetes but not officially enrolled in any lifestyle intervention, the informal walking partner is assumed to reduce his/her future diabetes related cost ($2,337) as well. We calculated an incremental cost-effectiveness ratio (ICER) for various scenarios with a discount rate (3%) and consumer price indexes adjusting to 2016 US dollars.

Results: Our preliminary analysis estimated that the lifestyle intervention’s ICER is $31,000 per Quality Adjusted Life Year (QALY) when the attrition rate is 50% during year 1. This ICER estimate declined to $13,000 per QALY, when the cash incentive for an intervention participant during the first three years could reduce the attrition rate to zero. The “zero attrition rate” was also achieved when an invention participant can walk with an informal partner. When the payment rates for an informal walking partner were a minimum wage and a median wage, the intervention’s ICER estimates were $27,000 and $55,000 per QALY, respectively. These ICER estimates declined to $10,000 and $30,000 per QALY, respectively, if an informal walking partner is also prediabetes and hence reduce his/her future diabetes related cost.

Discussions: Our preliminary findings imply that the additional payments for a participant or a participant’s informal walking partner would improve the economic efficiency of lifestyle interventions, unless the payment rate for an informal walking partner exceeds $15 per hour. When a positive spillover effect exists for a prediabetes informal walking partner, the intervention’s economic efficiency improves further.