Endometriosis and fibromyalgia co-occurrence: A comparative study of patient history and clinical profile

• Endometriosis and fibromyalgia frequently co-occur, even though in more than two-thirds of cases, the diagnosis of endometriosis preceded that of fibromyalgia. • Patients with endometriosis and fibromyalgia exhibit distinct clinical characteristics, including more severe chronic pelvic pain. • Patients with endometriosis and comorbid fibromyalgia demonstrates a higher prevalence of comorbidities, such as autoimmune diseases and psychiatric disorders, alongside a predominant phenotype of deep infiltrating endometriosis. To compare the clinical and anamnestic characteristics of women with endometriosis alone versus those with both endometriosis and comorbid fibromyalgia, in order to identify distinguishing features between the two groups. A prospective observational study was conducted on a cohort of 668 patients diagnosed with endometriosis. Patients reporting symptoms suggestive of fibromyalgia were assessed using the Patient Self-Report Survey for the Assessment of Fibromyalgia . Those with positive screening scores were referred for a rheumatologic evaluation. In a subgroup of 47 patients, the diagnosis of fibromyalgia was confirmed using the 2016 ACR diagnostic criteria. Patients’ history and clinical profiles were compared between subjects with only endometriosis versus those with co-existent fibromyalgia. Fibromyalgia was diagnosed in 7% (n = 47) of patients with endometriosis. In 72.3% of cases, the diagnosis of endometriosis preceded the onset of fibromyalgia. Deep infiltrating endometriosis (DIE) was the most common phenotype (55%) among patients with comorbid fibromyalgia. Chronic pelvic pain was significantly more prevalent in patients with fibromyalgia compared to those with only endometriosis (48.9% vs 24%; p < 0.05). Autoimmune comorbidities (51.1% vs 12.9%) and psychiatric disorders (17% vs 7.6%) were significantly more frequent in patients with both conditions (p < 0.05). Endometriosis patients with comorbid fibromyalgia represent a distinct phenotypic subgroup, marked by a higher prevalence of autoimmune diseases, psychiatric disorders, and conditions related to central sensitization. Investigating early risk factors—such as chronic pelvic pain, surgical history, and coexisting comorbidities—may facilitate earlier identification and more targeted management of this population.