Bias in Hair Cortisol Measures for Psychological Stress: Self vs. Professional Collection

The study investigates the feasibility and potential biases of self-collected hair samples for measuring hair cortisol concentration (HCC) as an indicator of chronic stress. Conducted within the Chitwan Valley Family Study in Nepal, 478 out of 510 eligible participants provided hair samples, with no significant difference in sample provision between self-collection (93%) and professional collection (97%). The findings suggest that while self-collection could enable broader population studies, it may introduce biases related to participant characteristics. However, these biases can be corrected through multivariable analysis, making self-collection a viable method for large-scale stress studies.