Background/Purpose:  Despite strong evidence that physical activity (PA) is associated with better quality of life, less pain and better functional status in persons with musculoskeletal diseases, uptake of PA in this population is low. PA is also associated with delayed rewards, which people tend to value less than immediately tangible benefits. Behavioral economics studies document that preference for smaller immediate rewards, as compared with larger delayed rewards — defined as delay discounting — is related to obesity, substance abuse and drug dependence. We sought to examine the relationship between delay discounting and uptake of PA in patients with musculoskeletal diseases.

Methods:  We conducted a cross-sectional study among patients attending an arthritis clinic in a tertiary medical center. Patients completed a questionnaire in which they were asked to choose between pairs of hypothetical monetary rewards in which one reward (e.g. $100) is offered immediately and an alternative, larger reward is offered after a time delay (e.g. $200 after one year). The amounts of the rewards ranged from $100 to $50,000 and the time frames ranged from no delay to a delay of 10 years. The delay discounting factor (DDF) was derived using a hyperbolic function and divided into quartiles. We assessed engagement in PA with the Yale Physical Activity Scale, using the overall Activity Dimensions Summary Index (ADSI) as well as the Vigorous Activity and Leisurely Walking indices. We conducted a multivariate regression analysis to establish the association between delay discounting and PA scores, adjusted for age, sex, BMI and race. 

Results:  The analysis is based on 172 study subjects with a mean age of 56 years (SD 14). 69% were female, the mean BMI was 29 (SD 7), and 34% were obese (BMI>30 kg/m²). The primary reasons for seeing a rheumatologist were back pain (46%), osteoarthritis (29%) and rheumatoid arthritis (23%). The average value of ADSI was 49 (SD 29). Mean values of both vigorous and walking PA indices were 3 (range 0-12). After adjusting for age, sex, obesity and race, a greater extent of delay discounting (greater preference for immediate rewards) was statistically significantly associated with lower overall PA (p=0.0168), as well as lower vigorous (p=0.0032) and walking (p=0.0370) activity indices (less engagement in physical activity). Adjusted least squared means for ADSI ranged from 38 in the highest quartile of DDF to 54 in the lowest quartile of DDF. Corresponding adjusted means for vigorous PA ranged from 3.4 for the lowest quartile of DDF to 1.7 for the highest quartile of DDF. A similar trend was observed for walking.

Conclusion:  Delay discounting, characterized by preference for smaller immediate rewards rather than larger delayed rewards, is associated with lower levels of PA among persons with musculoskeletal conditions. These data provide rationale and support for the development of incentives-based interventions, built on the principals of behavioral economics, to increase the perception of immediate rewards associated with PA among persons affected by musculoskeletal diseases. Such interventions may serve as a means of improving engagement in PA in persons affected by these conditions.

---

« Back to 2013 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/promise-of-behavioral-economics-delay-discounting-and-physical-activity-in-patients-with-musculoskeletal-diseases/