In previous studies, abnormal illness behavior in low back pain patients has been seen to be associated with, but not necessarily caused by, the amount of social or economic reward. The authors of this current study wanted to assess the relationship between these factors and patient's behavior, disability, and amount of depression.
75 nonmalignant low back pain participants took tests to assess their work disability, illness behavior, pain, anxiety, depression, and medical visits. The researchers reviewed medical records, and assessed the economic and social reward.
To see which reward affects which behavior, the patients were categorized into four groups: low economic/high social, high economic/low social, high economic/high social, and low economic/low social. The authors found that both social and financial rewards had independent effects on both disability and depression.
Patients with high social reward had higher levels of pain, more disability behavior, and had more distress. The high economic reward group reported more missed days from work and more depression. But, patients in the high economic group did not have more pain or more diffuse medical symptoms. Therefore, the authors suggest that rewards account for some effect on patients' illness behavior that cannot be explained by differences in symptoms, pain intensity, diagnosis, or depression.
The authors offer some explanations as to how or why reward affects patients:
As the study concludes the authors say that they cannot make a definite "causal link" between rewards and illness behavior, but that the evidence from their study supports the second and third theories from above.
Ciccone D, Just N, & Bandilla E. A comparison of economic and social reward in patients with chronic nonmalignant back pain. Psychosomatic Medicine 1999;61:552-563.