Business Associates' Involvement in US Health Care Data Breaches: Longitudinal Analysis.

Background: Health care organizations increasingly rely on business associates (BAs) to provide clinical, administrative, and technology services that require access to protected health information. While the Health Information Technology for Economic and Clinical Health (HITECH) Act and the Health Insurance Portability and Accountability Act (HIPAA) Omnibus Rule extended legal liability to BAs, the frequency and characteristics of data breaches involving BAs have not been systematically tracked across the entire post-HITECH reporting era. Understanding these trends is critical for health information managers and cybersecurity professionals who are directly responsible for managing third-party risk. Objective: The author examined the longitudinal trends in BA involvement in health care data breaches reported to the US Department of Health and Human Services (HHS) Office for Civil Rights (OCR) from 2009 to 2025, including changes in frequency, breach mechanisms, breach locations, and severity profiles of BA-involved incidents across 3 regulatory periods. Methods: The author conducted a retrospective longitudinal analysis of health care data breaches (N=6612) reported to the HHS OCR breach portal between October 2009 and December 2025. The author operationalized BA involvement as breaches reported by BA entities or flagged as BA-related. Using logistic regression models, the author estimated annual trends in BA involvement, breach mechanism, and breach location. Chi-square tests assessed associations between BA status and breach characteristics across 3 regulatory periods: pre-Omnibus (2009-2013), post-Omnibus (2014-2019), and 2020-2025. Proportion tests compared BA-involvement rates across periods. Results: BA-involved breaches accounted for 1950 of 6612 (29.5%) incidents and 285,718,494 (48.8%) of all affected individuals. The annual BA-involvement rate increased from 22.1% in the pre-Omnibus period to 36.6% in the 2020-2025 period ( Conclusions: Building on prior evidence linking BA involvement to breach severity, this study demonstrates that BA-involved health care data breaches accelerated substantially across the post-HITECH reporting era, with the steepest increase beginning in 2020. The concurrent growth of hacking and the concentration of breaches on network servers coincided with digital transformation, cloud migration, and the ransomware epidemic, which may have amplified third-party risk exposure. Health information managers and cybersecurity professionals should prioritize BA risk management strategies that account for the evolving threat landscape, including enhanced vendor security assessments and data compartmentalization requirements.