Kruk has contributed to the field of
public health by developing novel measures of health system quality and assessing how these systems' performance influences population demand for healthcare, health outcomes, and trust, using measures, implementation science and econometric methods to design and evaluate large-scale health system reforms. Her research also found that universal health coverage in low- and middle-income countries could prevent 8.6 million deaths annually if it includes high-quality care to address both non-utilization and poor-quality health services. Building on this research, she, along with Todd Lewis and colleagues, developed a survey to assess health system performance from the viewpoint of the population applicable to countries at all income levels. Results from this People's Voice Survey showed that fewer than 50% of people across 16 countries feel secure in their health systems. In 2015, Kruk and collaborators proposed the first formal framework for resilient health systems. This drew from lessons from the Ebola epidemic, emphasizing the importance of effective response, maintenance of core functions, and post-crisis reorganization. Additionally, alongside Lynn P. Freedman, she proposed a framework for evaluating health system performance in developing countries, reviewing indicators across effectiveness, equity, and efficiency to assist policymakers in assessing the impact of various policies and expenditures. Through the Lancet Commission on Investing in Health, Kruk and colleagues introduced a framework to achieve health gains by 2035, highlighting high returns on health investments, the potential for a "grand convergence" in health outcomes, fiscal policies to reduce non-communicable diseases, and progressive universalism for universal health coverage. Another facet of Kruk's work focused on health system performance in maternal, neonatal, and child health. Analyzing basic maternal care quality in health facilities across five sub-Saharan African countries, she revealed lower scores in primary care facilities, which handle a significant portion of deliveries, and a consistent association between low delivery volume and poorer quality. Along with Sanam Roder-DeWan, she proposed service delivery redesign that would shift all deliveries to higher level health facilities for all women over time in low-income countries as a way to reduce persisting high rates of newborn mortality. In a survey conducted with colleagues in Tanzania, she demonstrated that 19-28% of women in Tanzanian health facilities experienced disrespectful or abusive treatment during childbirth, underscoring the urgency of solutions to ensure dignity and reduce maternal mortality. She further showed that disrespectful treatment during childbirth led to lower satisfaction, perceived poorer care quality, and reduced intention for future deliveries at the same facility, emphasizing the need for better interpersonal care in
maternal health. She led papers for global research collaborations in maternal and child health, including the Lancet Maternal Health Series (2016) and the Lancet Child Health Series (2022). == Personal life ==