Quantifying age-related disparities in outpatient psychotherapy utilization: a representation quotient analysis of routine data from 29 university clinics in Germany

Background: Although mental disorders are highly prevalent among older adults, evidence suggests that they underutilize psychotherapy. However, formal estimates of their actual representation in routine clinical settings are scarce. This study applied a representation quotient approach to identify and quantify age-related disparities in outpatient psychotherapy utilization in Germany. Methods: We analyzed data from 13,635 adult patients who initiated cognitive-behavioral therapy between 2018 and 2023 at 29 university outpatient clinics. Using a representation quotient approach, we compared the observed proportions of young-old adults (65–74 years) and old-old adults (≥75 years) with prevalence-stratified population age distributions. The robustness of the results was investigated by extensive sensitivity analyses, including alternative prevalence assumptions and adjustments for long-term care needs. Results: Even under conservative assumptions, young-old adults only accounted for about 25% and old-old adults for about 13% of their expected proportion. In contrast, young working-age adults (18–34 years) were particularly overrepresented in the sample. Underrepresentation of older adults was most pronounced among patients with post-traumatic stress disorder, eating disorders, and dysthymia, less pronounced among patients with generalized anxiety disorder, and not significant among patients with pain disorders. Conclusion: This study demonstrates the utility of representation quotients for systematically identifying and quantifying age-related disparities in psychotherapy utilization based on routine care data. Our analyses of large-scale data from university outpatient clinics in Germany revealed a marked underrepresentation of older adults in this setting. These findings highlight the need to improve access to, and utilization of, psychotherapeutic services for older adults.