In this study, we analysed the factors associated with the lifetime occurrence of IPs on PHC level, the recent IPs within the past 12 months on PHC level, and prevailing attitudes toward this practice among patients receiving the four key healthcare services in Ukraine: childbirth, neonatal care, acute myocardial infarction, and acute stroke care. The findings provide critical insights into the factors that are linked to an increased likelihood of making IPs and the development of positive attitudes toward this practice.

Our study demonstrated that female patients were more likely to have made IPs both over their lifetime and within the past 12 months on PHC level. This finding aligns with previous research that suggested that women were more likely to engage in IPs, potentially due to their higher utilization of healthcare services. Thus, it has been shown that women tend to have more frequent doctor visits and a greater demand for diagnostic and therapeutic interventions, particularly in relation to reproductive health, leading to increased interactions with healthcare providers and, consequently, a higher likelihood of making IPs [37–41]. Additionally, sociocultural factors, including the desire to maintain positive relationships with healthcare professionals, may further contribute to this trend [11, 37, 39]. Women may feel particularly compelled to ensure high-quality care during critical periods such as pregnancy and childbirth, which can drive IPs aimed at securing expedited or enhanced services and their quality. This behaviour is especially prevalent in contexts where healthcare quality is perceived as inadequate without such payments [42]. In this context, it is important to note that evidence shows women in the United States make approximately 80% of healthcare decisions for their families, yet often lack adequate healthcare coverage themselves [43].Thus, it is crucial to prioritize women in the design of information campaigns, ensuring they have access to reliable, up-to-date information and support, particularly during critical life stages such as pregnancy and childbirth. Furthermore, future research should focus on systematically examining the gender-specific needs and vulnerabilities that women in Ukraine face with respect to IPs. Such insights are crucial for developing more precisely targeted interventions to effectively address and mitigate these challenges.

We also observed an association between the number of people in the household and the likelihood of IPs, which similarly might be explained by increased utilization of healthcare services and more frequent engagement with healthcare workers. To this end it is also crucial to mention that 80% of women are responsible for household healthcare decisions (Matoff-Stepp et al., 2014).

Previous research suggests that older patients tend to make fewer IPs [42]. Although we did not observe any significant association between age and the likelihood of making IPs either over a lifetime or in the past 12 months (potentially due to the way age groups were categorized) on PHC level, we found that older patients generally held negative attitudes towards IPs. This may be explained by the fact that older individuals tend to be more financially vulnerable and have greater exposure to the healthcare system, owing to higher utilization of services and longer periods of healthcare use throughout their lives compared to younger individuals [42]. It is important to examine whether, with age, patients in Ukraine tend to make informal payments less or whether their negative attitudes towards IPs fail to translate into changes in their behaviour. Additionally, the prevalent negative attitude among older patients could be leveraged in healthcare service monitoring, as these individuals may potentially serve as valuable sources of information regarding IP practices.

Moreover, our results demonstrated that individuals with lower income levels were more likely to hold negative attitudes toward IPs, which might be due to the catastrophic financial burden such payments impose on low-income households [14, 44, 45]. This challenge is further compounded by prior research showing that in countries like Ukraine and Romania, where IPs are prevalent and poverty rates are relatively high, patients bear a disproportionately heavy burden and difficulties in paying for healthcare services [14]. Therefore, households with low-income levels should be prioritized and targeted by state programs to ensure that healthcare services are inclusive, accessible to all, and aligned with the goal of achieving universal health coverage.

Also, our results suggested that individuals who did not support ongoing healthcare reforms, including those aimed at more efficient and transparent resource allocation, strategic purchasing with a purchaser-provider split, clearly defined health benefits, and new payment methods for healthcare providers – were more likely to have a positive attitude towards IPs and had higher odds of making informal payments for healthcare services both over their lifetime and within the past 12 months. So, individuals with negative attitudes toward healthcare reforms and ongoing changes may be less likely to alter their behaviour or beliefs regarding IPs. This finding can also be interpreted through the lens of prevailing social beliefs and norms regarding IPs and healthcare services in Ukraine and other Central and Eastern European countries, where such payments are often culturally ingrained [11–13]. Overall, studies from these regions have demonstrated that, despite a general desire to address the issue of IPs, the public frequently see these payments as necessary to obtain more personalized care, improved quality, and expedited access to healthcare services [14, 46–48]. We emphasize the need for a more nuanced understanding of how social norms and health beliefs shape patients’ attitudes and behaviours toward IPs. These factors must be carefully considered when developing healthcare service delivery strategies.

Although no associations were observed between outcome variables and changes in residency due to the full-scale war, patients who reported no changes in informal payments or a worsening situation after the war were more likely to have made payments in the past 12 months and at some point, in their lives on PHC level. This is most likely linked to the overarching health beliefs and behaviours of these respondents, but it could also be a direct effect of the war. Future research should carefully investigate how, and to what extent, the full-scale war has influenced the behaviour of both patients and providers regarding informal payments in Ukraine.

Finally, another interesting finding is the regional variation in the likelihood of IPs, particularly between the central macro-region with Kyiv city and other macro-regions (i.e., southern, northern, western, and eastern). This may be attributed to differences in the timing of healthcare reforms as well as the effectiveness of their implementation and later enforcement on the ground, leading to varying outcomes in these localities. Additionally, the number of people residing in rural areas may also influence these associations. There is evidence suggesting that individuals in rural areas may be more willing to make IPs [13, 49–52]. However, it is also important to consider that this willingness might be influenced by the low-income levels prevalent in the rural areas [13, 35, 50, 53]. We thus, argue that regional differences may play a crucial role in shaping context-specific and more efficient approaches to healthcare service delivery.