A lack of sociodemographic participant diversity in endometriosis evidence risks unrepresentative clinical guidance: a structured review of the evidence contributing to a NICE guideline.

Background: Women who are black are less likely to be diagnosed with endometriosis than white women. There is no confirmed biological basis, so this likely represents structural barriers around health care. There is a lack of evidence exploring the interface between ethnicity and symptoms or experience of care and treatment.

Aim: To map recording of sociodemographic diversity in the evidence informing an endometriosis guideline.

Method: Inclusion of study setting, ethnicity, age, and socioeconomic status was documented within the evidence cited in National Institute for Health and Care Excellence (NICE) NG73 (2017) . Included were 44 studies with 43 sample groups from the chapters: 'Signs and Symptoms', 'Information and Support', and 'Diagnosis'. Data were extracted independently by two researchers.

Results: No studies were conducted in primary care. The evidence cited in 'Signs and Symptoms' and 'Diagnosis' was exclusively from tertiary care. 'Information and Support' included 9/16 studies from tertiary care, and 7/16 recruited through community and advocacy networks. For ethnicity, 4/44 studies formally reported participant ethnicity (three from 'Information and Support', one from 'Diagnosis'). In these, 93%, 90%, 60%, and 75% of participants were white/Caucasian (mean 79.5%). For age, 3/44 studies included adolescents. Many studies excluded women who were deemed outside reproductive age. For socioeconomic status, eight studies, all from 'Information and Support', reported socioeconomic status in some form. The majority of participants were tertiary educated.

Conclusion: These results highlight the missing demographics within evidence cited in a national guideline for endometriosis. These align with documented inequities in diagnosis of endometriosis and warrant urgent attention.