This study sought to compare chronic pain patients that had a medical explanation for their condition versus chronic pain patients who did not. Specifically, the study assessed and compared the patients' psychological diagnoses, iatrogenic experiences, and medical usage.

125 subjects were included in the study, and those without medical explanations tended to be younger and female.

Those without medical explanation had experienced major depression either currently or lifetime more often than chronic pain patients with a diagnosis (13.8 to 6.6%); however there was little difference between the degree of anxiety and depression between the two groups. Interestingly, the researchers found those without explanation had a particularly higher rate of a family member experiencing chronic pain or alcohol abuse. Since 52% of the patients had a first degree relative with chronic pain, and 25.9% with alcohol abuse, the authors suggest that there may be some relationship between family history and somatization.

As predicted, the medically unexplained patients experienced high rates of iatrogenic factors. The authors expound upon the most common occurrences and their effects:

"We observed that this group of patients reported a significantly higher frequency of direct disconfirmation of their pain by the doctors. We suggest that patients with medically unexplained symptoms are often exposed to attitudes that may paradoxically reinforce their determination to maintain the sick role, since to do otherwise would confirm the doctor's own view—that it was 'all in the mind' after all."

Drug misuse or abuse was much lower in both groups than was expected at the beginning of the study, and the researchers found that there were no differences between the two groups in the rate of such abuse.
In determining the coping strategies of the two groups, they found them comparable, with an exception in the topic of catastrophising. Catastrophising has been related to feelings of an inability to control pain and depression. Since the patients do not have a diagnosis, the authors suggest they feel their pain is "mysterious." In such a case, the patient will be less likely to use coping skills or believe they possess the power or control to decrease pain—and more likely to catastrophize. When encountering such a situation the authors recommend:

"We therefore draw attention to the need for doctors to be very sensitive to the beliefs of patients when no immediate cause for chronic pain can be found. It is essential that the patient is not led to believe their pain is 'imaginary' thus potentially triggering a breakdown on the doctor-patient relationship, and a desire for further investigations 'to prove the doctor wrong.' Patients also require valid and understandable explanation for their symptoms, to reduce the tendency to view the process as not only mysterious but also beyond control."

Kouyanou K, Pither C, Rabe-Haketh S, Wessely S. A comparative study of iatrogenesis, medication abuse, and psychiatric morbidity in chronic pain patients with and without medically explained symptoms. Pain 1998; 76: 417-426.