: Endometriosis is often described as a progressive disease beginning with menarche and menstrual bleeding. However, this is controversial, as the origin of the disease remains unknown. The objective of this study was to investigate the association between the severity of endometriosis and age at initial diagnosis.

: This prospective multicenter cohort study included 964 patients, newly and histologically diagnosed with endometriosis during laparoscopic treatment. The main outcome measures were diagnostic lesions with staging according to rAFS (revised American Fertility Society) scores, intensity of pain based on VAS (Visual Analog Scale) scores and quality of life from SF-36 questionnaire results. Age was treated as a categorical variable. Univariate and multivariable analyses (linear and multinomial ordinal) were conducted taking into account two by two multiple comparisons. The results were expressed with effect sizes and 95% confidence intervals.

: No significant association between age and rAFS stage was found (p=0.053). The percentage of patients with a deep nodule ≥ 2cm was respectively 20%, 25%, 21%, 18% and 9% for patients aged ≤ 25, 26-30, 31-35, 36-40 and >40 years respectively (p=0.005). For dysmenorrhea, 64%, 61%, 54%, 51% and 32% of patients aged ≤25, 26-30, 31-35, 36-40 and >40 years respectively reported a VAS score of ≥7 (p≤0.001).

: Prospective data obtained in patients newly diagnosed with endometriosis, revealed that the rAFS score is not related to patient age, and that the percentage of patients with a nodule ≥ 2cm and severe dysmenorrhea did not increase with age. These percentages were significantly lower in patients aged > 40.