Substance use among HCPs in Kenya is of major concern. While use does not necessitate abuse, it can still lead to impairment, affect the quality of care and be detrimental to patient safety [8]. Indeed, compared to many other vocations, the direct consequences of substance use on service delivery in HCPs can have severe effects on the lives of many. This is particular significant in the context of Kenya, where there is already a significant shortage of HCPs, and a single HCP can be responsible for the health outcomes of many patients [10,15].

In this diverse convenience sample of HCPs, 51.7% reported having used a substance in their lifetime, which is slightly lower than the general Kenyan population aged between 15-65 years, where lifetime use was reported to be 57% [4]. The 51.7% figure for lifetime substance use refers to the proportion of HCPs in the convenience sample who reported ever using any substance at least once during their life, whether it was alcohol, tobacco, cannabis, opioids, or other substances.

A majority of our participants had tried alcohol in their lifetime, and it was the most frequently used substance in the past three months. Previous findings in Kenyan HCPs similarly found the highest lifetime use of any substance was for alcohol at 35.8%, significantly lower than our own findings of 93.7% [14]. However, only 5.2% of our participants reported consuming at least one alcoholic beverage 5 or more days a week, and 25.9% reported using 1-4 times a week. Over half of the participants who used alcohol reported a strong desire or urge to use in the past 3 months, and a quarter reported their use had led to health, social, legal and financial problems. Importantly, 18.6% of HCPs who used substances in this study reported failing to do what was expected of them due to their alcohol use in the past 3 months. This harmful pattern of use, which may affect HCP performance, is concerning as it may also directly affect patients seeking healthcare services. Doctors and nurses require optimal cognitive performance due to the nature of their jobs, and the effects of alcohol on cognition are dependent on patterns of use. While moderate consumption has been suggested to be beneficial over time [21], binge drinking, hangovers, as well as intoxication and withdrawal may still affect HCP performance and have lasting detrimental effects on cognition and decision making [22,23]. Our study did not measure patterns of alcohol consumption nor units consumed, which can be important for deciphering these effects on HCP performance, and an important consideration for the design of future substance use studies.

Interestingly, cannabis was the second most reported substance for lifetime use in our study at 28.9%, which is significantly higher than the previous findings of 9.3% in Kenyan HCPs [14]. While cannabis use in the general population of Kenya is said to have almost doubled in the last five years, overall lifetime use among those aged 15-65 year remains much lower than our study population, at 3% [24]. A recent meta-analysis done on studies from various continents, found a 37% lifetime use of cannabis in MD’s and medical students, higher than the 25% lifetime use among 15–64-year-olds in the general European population. Work stress was suggested as a potential cause for this difference and may offer a possible explanation to our findings as well. The daily use of cannabis from this meta-analysis was at 0.1% in physicians [25], much lower than our own daily use findings of 5.4%.

Tobacco products had the third highest percentage for lifetime use at 27.6%, similar to previous findings in Kenyan HCPs of 23.5% [14]. Among our participants who used substances, almost half reported using tobacco products in the past three months and these were also the most used daily substance. Both studies on Kenyan HCPs found higher lifetime usage of tobacco than in the general population in Kenya, where lifetime use was 15% [4]. Quitting smoking has immediate health benefits, and therefore raising awareness on the benefits of stopping smoking is crucial. HCPs can play a vital role in counseling their patients on smoking cessation. However, evidence suggests that doctors who smoked or were former smokers were less likely to counsel their patients on quitting smoking. These findings also translated to other behavioral practices of doctors, such as nutrition counselling from doctors who followed healthy diets [26]. This suggests that the lifestyle choices of HCPs may indirectly impact behavioral choices of their patients, though this needs to be investigated further in Kenya.

Our results for lifetime use of opioids was higher than previous findings in Kenyan HCPs at 5.3%, compared to previous findings of 3.9%. Our study also found higher lifetime use in sedatives or sleeping pills than previous findings. However, our findings for lifetime use of cocaine, inhalants and hallucinogens were lower, and amphetamine type stimulants also had a marginally lower lifetime use in our study compared to previous findings[14]. For all of these substances, there is evidence suggesting lingering effects on cognitive abilities which may affect HCP performance, even following a period of abstinence [7,27]. Therefore, understanding patterns of use and raising awareness of the lasting effects of substances of abuse is crucial in Kenyan healthcare settings. Among our substance using cohort, opioids were reported to cause the strongest desire or urge to use, and led to the most health, social, legal or financial problems in the last 3 months. Additionally, participants who used opioids were most likely to report difficulties in controlling, cutting down or stopping use, which remains a concerning fact.

In this study, being unmarried was correlated with substance use, mirroring other research findings [5,15,25]. Being unmarried is thought to result in a lack of social support and social isolation, which are both risk factors for substance use [15]. Research has suggested that the change in social role associated with marriage has a causal deterrent effect on psychoactive substance use [28]. It would be useful for future research to determine if these reasons for decreased substance use translate into the Kenyan context as well, in order to better understand patterns of substance use in our population.

Though there was a slightly higher percentage of female substance users in this study, the difference in prevalence between the genders was not statistically significant, contrasting previous findings. The male gender (sex at birth) is strongly associated with substance use in both HCPs and the general population [4,5,12,14–16,24,25]. Substance use affects genders differently, both physically and in terms of roles, norms and consequences; and therefore, affects the pattern and prevalence of substance use, generally translating into fewer female substance users [14,29]. More investigation is required to not only replicate but also determine why there may be no difference in substance use prevalence between the genders in Kenyan HCPs.

This study had a relatively young population of HCPs, so the age difference between substance users and non-users was not large. Despite this, there was statistical significance that suggested younger HCPs are more likely to use substances. This may be compared to findings from previous research [16,25,30,31] which show that younger HCPs may be more likely to be unmarried, possibly leading to the same risk factors described above such as social isolation. Younger HCPs may be new to their fast-paced, highly stressful work environments and may perhaps turn to substances to cope; however, this theory requires further examination in our context.

Doctors and allied health staff were more likely to use substances than nurses. This is consistent with previous findings in Kenya and Nigeria, where it was suggested that nursing is a majority female-dominated profession, while doctors were more likely to be males, and hence a likely association with substance use [11,15]. Furthermore, it has been suggested that nurses in Kenya have strong social support systems that may prevent unhealthy coping using substances, which perhaps sheds light on our findings [15]. Another factor may be the prescription privileges doctors have that nurses do not, which may lead to higher accessibility to controlled substances for doctors and potentially explain part of the use prevalence difference in the cadres. Self-prescription of medicines is a unique factor that may lead to substance use in HCPs. Hartnett and colleagues found that anesthetists and surgeons were more likely to self-prescribe potentially addictive medications, underestimating their risk for addiction due to their familiarity with the drugs. General practitioners were also more likely to self-prescribe, and this was suggested to be because of their perceived stigma of attending a colleague [32]. In our findings, the specialties of surgery and internal medicine were also linked to a higher prevalence of substance use. The intense nature of surgery and potentially being in life-or-death situations daily, may lead to increased substance use to help cope with work related stress [9,33]. Additionally, potentially high workloads and long hours for internal medicine physicians in Kenya may propagate unhealthy coping habits, but this theory merits further investigation.

HCPs from private or faith-based institutions were more likely to use substances than participants from public institutions. The reasons for this are largely unknown, however there is evidence of faith based hospitals having poor organizational structures [34] which could possibly lead to less regulation of substances of abuse. Regardless, further investigation into higher rates of substance use in HCPs in faith-based organizations is needed. One possible explanation for the higher rates of substance use in private facilities may be due to higher income brackets for HCPs in these facilities.. Our findings are similar to findings from a study done in Brazil, where physicians and nurses with higher incomes were more likely to use alcohol [16]. In addition, a multi-country analysis of 55 low income and middle-income countries also found a clear positive association between increasing socioeconomic status and current drinking. The association between increasing wealth quantiles and current drinking was stronger in females than males [35]. These results are supported by a systematic review on the prevalence of tobacco use in healthcare workers, where it was found that in low and middle income countries (LMICs), there was a positive association between smoking and higher socioeconomic status particularly in women [36]. Higher socioeconomic status may facilitate easier access to substances due to increased affordability and doctors tend to earn more as compared to the nurses or the allied health staff. Additionally, higher income may be linked to higher educational attainment, which can provide access to more resources. This study, like others [14,35], found that HCPs with higher levels of education were also more likely to use substances. One possibility is that higher educational attainment in HCPs is associated with a better job position and higher income, leading to higher affordability and accessibility of substances. More in-depth examination of the associations between socioeconomic status of HCPs and substance use in Kenya is required, as well as research on reasons for different prevalences in substance use in different healthcare institutions.