Generalized anxiety disorder (GAD) is characterized by persistent worry and physical symptoms, with prevalence estimates ranging from 0.8% to 8%. Researchers utilize various tools, such as standardized diagnostic interviews and self-report questionnaires, to estimate GAD prevalence in population-level studies. However, the diagnostic accuracy of these tools varies greatly. This scoping review aimed to identify the tools used for GAD prevalence estimation and assess the extent to which diagnostic tool accuracy is reported.

A systematic search was conducted in MEDLINE, Embase and PsycINFO using MeSH terms and keywords related to GAD prevalence. No date restrictions were applied. Studies were eligible if they used nationally or regionally representative samples and defined GAD based on DSM-5, ICD-11 or older case definitions. Studies focusing solely on specific sub-groups were excluded. Data extraction included study characteristics, diagnostic tools and reporting of test accuracy.

A total of 537 studies were initially identified, with 48 meeting inclusion criteria, published between 1994 and 2024. Most studies were conducted in Europe (43.75%) and employed cross-sectional designs (92%). Structured diagnostic interviews were the most commonly used tool (77.08%), although self-report questionnaires gained popularity after 2005. Among the included studies, 62.5% reported test accuracy, often addressing validity and reliability.

Despite the widespread use of diagnostic tools in prevalence studies, test accuracy is not consistently reported, which may impact the reliability of prevalence estimates. The variability in agreement between self-report questionnaires and structured diagnostic interviews highlights the need for transparent reporting of test characteristics to improve the validity of GAD prevalence assessments across populations.