Background: Fibromyalgia (FM) is a disease with medically unexplained widespread chronic pain, often leading to difficulties in therapeutic relationships between patients and physicians. The purpose of this study was to measure both patients’ and physicians’ experiences with “negative responses” (invalidation), such as “discounting” and a “lack of understanding” for FM patients.

Methods: A cross-sectional postal survey was conducted. Participants were selected randomly among 500 members of the Japan Fibromyalgia Support Association and 1,000 member physicians from two rheumatic disease associations. The response rate was 72.6% and 32.2%, respectively. Of these, 304 patients’ and 233 physicians’ answers were analyzed. The Illness Invalidation Inventory (3*I) was used to measure negative reactions after checking the reliability and validity of the Japanese version. To compare the 3*I score within each categorical variable, the Kruskal-Wallis or Mann-Whitney U test was used; for the comparison between patients and physicians, the Independent Samples t-Test was used.

Results: Regarding discounting, patients with severe (vs. moderate) conditions and users (vs. non-users) of complementary treatment had higher scores (p = 0.003, 0.03, respectively). Among physicians, those who registered (vs. non-registered) with the FM consultation network had higher discounting scores (p = 0.02). Male (vs. female) physicians and physicians who were not willing to (vs. willing to) accept FM patients had higher scores in discounting (p = 0.006, 0.03, respectively) and a lack of understanding (p = 0.03, <0.001, respectively). Physicians had higher 3*I scores than patients for discounting only (patients: 2.04 ± 0.98, physicians: 2.58 ± 0.69; p < 0.001).

Conclusions: Compared with studies abroad, patients’ 3*I scores were moderate, but the discounting results reflected FM difficulties that were not merely internal disorders. The study revealed that physicians were aware of their negative reactions, and furthermore, the physicians who actively accept FM patients may recognize more difficulties. To build better patient-physician relationships, providing support not only for patients but also up-todate information for physicians is recommended.