Achieving equitable access to healthcare requires addressing both financial and systemic barriers that shape healthcare utilization. While health insurance schemes play a crucial role in reducing financial barriers, physicians as gatekeepers and supply-side disruptions can influence access to care. Across four chapters, this dissertation examines how insurance schemes, physician behavior, pharmaceutical supply chain resilience and supply disruptions shape both the access to and utilization of health services. This summary provides an overview of the key findings from each chapter, and their broader implications.

This dissertation shows that while a patient's insurance status influences access to pharmaceutical treatments, the extent of this impact is further shaped by physician behavior and practice composition. Privately insured patients in Germany receive less complex treatments, a pattern that is further influenced by the composition of insurance schemes within a physician’s practice. These dynamics suggest that physicians adjust their treatment decisions based on the insurance landscape they operate in, creating disparities in access that go beyond direct financial barriers. In the United States, where out-of-pocket costs vary widely, the physician’s prescribing behavior has become an increasingly important determinant of access to cost-effective medicines. While generic prescribing has increased over time, variability between physicians has grown substantially, highlighting that the choice of physician plays a greater role in determining whether a patient receives a generic or brand-name medicine than their insurance status.

While financial and behavioral factors influence access at the point of care, systemic factors, including pharmaceutical supply chain resilience, are equally critical in determining whether medicines remain available. The COVID-19 pandemic demonstrated the vulnerability of globalized pharmaceutical supply chains, with medicine shortages increasing sharply in the wake of supply disruptions. However, the findings of this dissertation indicate that Germany’s pharmaceutical supply chain exhibited a relatively strong level of resilience, with medicine shortage levels recovering to pre-pandemic levels within approximately ten months. Despite this recovery, medicines with high global dependency and those in highly competitive markets were particularly vulnerable to shortages, reinforcing the need for balancing cost-efficiency with supply security.

The consequences of medicine shortages extend beyond temporary supply disruptions. The 2018 global recall of valsartan illustrates how pharmaceutical shortages reshape healthcare utilization and exacerbate care fragmentation. Even when alternative treatments are available, patients often require additional consultations, leading to increased burdens on general practitioners and pharmacists. The recall resulted in a short-term rise in healthcare utilization, and pharmacy fragmentation persisting for up to a year, affecting one in five valsartan patients. Additionally, pharmaceutical costs for antihypertensives rose by 5.3%, imposing a financial strain on insurers. These findings highlight the hidden costs and operational inefficiencies that emerge when supply chains fail to ensure adequate supply.

By integrating financial, behavioral, and systemic perspectives, this dissertation provides new empirical evidence on the mechanisms shaping access to pharmaceuticals. It highlights the interplay between physician decision-making, insurance structures, and supply chain vulnerabilities, demonstrating that access is not merely a function of financial coverage but also of how healthcare providers and supply networks respond to systemic pressures. Policymakers aiming to improve healthcare access must consider not only financial levers but also physician incentives and supply chain resilience strategies. Ensuring sustainable and equitable access to medicines requires carefully calibrated policies that mitigate disparities, strengthen supply chains, and balance efficiency with resilience in pharmaceutical markets.