The Use of Caffeinated Substances by Surgeons for Cognitive Enhancement

Andreas G. Franke, MD, PhD, MA; Christiana Bagusat, Dipl-Soz; Carolyn McFarlane; Teresina Tassone-Steiger; Werner Kneist, MD; Klaus Lieb, MD


Annals of Surgery. 2015;261(6):1091-1095. 

In This Article


This study investigated for the first time the prevalence of coffee, caffeinated drink, and caffeine tablet use for CE among surgeons in Germany. Despite the media hype about the putative widespread use of CE substances and increasing numbers of theoretical papers dealing with this subject, valid scientific data is widely lacking about the prevalence of substance use for CE and factors associated with this use, with the exception of a few older epidemiological studies.

Substance use with the particular intention of CE has begun to be examined predominantly among students.[3,19–21] In this respect, aspects of autonomy, social pressure, fairness, justice, and further philosophical and ethical aspects play an important role.[22,23] There is no doubt that drug use for CE among physicians must be considered differently than use among students.[17] The scientific literature describes the difficult working conditions of surgeons (including for example shift work and long working hours).[8–11] Extremely difficult working conditions for surgeons may put patients at risk of medical errors during surgery based on reduced vigilance due to shift work, working the night shift, long working hours, and a heavy work load.[11–16] In this respect, evidence from sleep-deprivation studies suggests that caffeine has pro-vigilant effects.[4,24,25] This study found that the surveyed surgeons used caffeinated substances to cope with fatigue when doing shift work and when working long hours.

Many higher cognitive functions are important during surgery, including long-term concentration, planning, memory, and risk-evaluation. However, most studies of substances used for CE involve healthy young subjects, not surgeons, and employ artificial settings for examining putative pro-cognitive effects of drugs. A recent clinical trial by Aggarwal and colleagues reported pro-cognitive effects of caffeine and taurine in sleep-deprived surgeons, which restored simulated laparoscopic performance to rested levels. However, a reduction of errors could not be demonstrated.[7] Interestingly, at least 2 studies have demonstrated that caffeine may be as effective as (psycho-)stimulants (eg, methylphenidate, amphetamines) or modafinil in enhancing simple cognitive functions, such as vigilance and psychomotor functions.[24,25]

Unlike the use of many stimulants, the use of coffee, caffeinated drinks, and caffeine tablets is legal. Nevertheless, the decrease in the pro-vigilant effects of caffeine over the course of the day must be evaluated by the users themselves, and adverse effects, including tremor, gastrointestinal problems (ie, nausea, stomach ache, etc), and symptoms of withdrawal, must also be considered by users.[26,27]

Regarding prevalence rates, the rates of coffee use in this study are slightly lower than those reported in previous studies.[1,2] However, previous studies did not ask about the reasons underlying caffeine use and did not specifically address surgeons. An important study about personal health habits for avoiding burnout revealed recently that 94% of 7200 surveyed US surgeons having used caffeine in the last year with 75% daily use of caffeine.[28] Because this study did not ask whether caffeine was used directly for CE, these data are not directly comparable with ours, but nevertheless demonstrate the high prevalence rate of caffeine use among surgeons.

Compared with our previous study among students, we found a lifetime prevalence of 53% for the use of coffee with the particular intention of CE, 39% for the use of caffeinated drinks, and 11% for the use of caffeine tablets among high school (mean age: 19.3 years) and university (mean age: 24.0 years) students.[3] One reason may be that caffeinated drinks are marketed as "energy drinks" and target young male users, such as students.[29,30] The higher lifetime prevalence rates for coffee and caffeine tablet use by surgeons may also be explained by the surgeons' higher age. Surgeons have lived longer, and therefore there is a higher probability that they have used such substances. However, the last-month prevalence rates for all substances were significantly higher for surgeons than for the student sample, and the last-week prevalence rates were nearly 0% for students. This finding may suggest that surgeons have a more constant need for pro-vigilant substances; although this is speculative, this is in-line with what we know about surgeons' working conditions mentioned earlier.

However, in another study among students, coffee was used regularly by 20% of the surveyed students.[21] Previous studies have shown that caffeine use for CE derives from the students' world, which is not comparable to the situation of the surgeons in this study. Nevertheless, surgeons were students when they were younger.

CE is a stigmatizing subject. In a previous study of 2600 students, we found a 1-year prevalence rate of almost 20% for the use of "pharmaceuticals or illegal drugs which you cannot buy in a drug-store and which were not prescribed to you to treat a disease" with the sole purpose of improving cognitive performance.[31] That study used the so-called randomized response technique (RRT), which guarantees an especially high degree of privacy, anonymity, and confidentiality when a person is prompted to answer sensitive questions about socially undesirable or illicit behavior.[32,33] In this study, we did not use RRT; rather we asked directly about coffee, caffeinated drink, and caffeine tablet use, leading to reduced anonymity compared with the RRT. Thus, the prevalence rates for caffeine use for CE may be even higher than reported here. This is supported by findings of a previous survey among surgeons regarding the use of prescription and illicit drugs for CE; the RRT resulted in significantly higher prevalence rates (20% lifetime prevalence) compared with non-RRT questions (9% lifetime prevalence).[18]

In the study on caffeine use for CE among students,[3] we found sex to be associated with the use of caffeine for CE. In this study, this was only confirmed for caffeinated drinks (see Table 4). However, contradictory results have been reported regarding the influence of sex.[31,34]

The prevalence rates for caffeine use for CE were significantly higher in this study than the prevalence rates for the use of stimulants, modafinil, or beta blockers.[18,19,21,35]

Furthermore, we were able to show that age (for coffee, caffeinated drinks, and caffeine tablets), pressure to perform in the surgeon's private life (coffee), pressure to perform in a way that is perceived to be harmful (coffee), living with children (caffeinated drinks), and satisfaction with professional success (caffeine tablets) are positively associated with the use of caffeine among surgeons. Other factors were not found to play a role in the use of caffeine for CE. The pressure to perform either professionally or in private life and gross income were positively associated with the use of prescription and illicit drug use for CE.[18] Caffeine use for CE could only be confirmed for pressure to perform in the surgeon's private life.

A prevalent motivation for using caffeinated substances seems to be associated with the demands and stress of a surgeon's workload. This study has a few limitations. The response rate of 36.4% is fairly low. Questionnaires were distributed during conference breaks, and we had little control over the return of the completed questionnaires.

The survey was distributed at 5 international conferences of the German Society of Surgery, so we tried to avoid multiple participating by asking potential participants if they had participated before. Even if this procedure was the most pragmatic way to avoid multiple participating, it relies upon participants' recalling and fidelity. However, because the conferences were all within less than 1 year and the surveys were distributed always by the same authors, we are confident that multiple participating was unlikely.

Furthermore, substance use in general and substance use for CE in particular is a highly stigmatizing subject, even in anonymous questionnaires, and this may have led to low response rates. We did not use the aforementioned RRT for guaranteeing an especially high degree of privacy, anonymity, and confidentiality.[32,33] Therefore, the presented prevalence rates for caffeine use for CE may be even higher than those for prescription and illicit drugs because of the stigmatization of misusing prescription or illicit drugs. This assumption is underlined by a study that showed a significantly higher lifetime prevalence rate of prescription and illicit drug use for CE among surgeons of 20% (RRT) compared with the non-RRT lifetime prevalence rate of 9%.[18]

Regarding the context of caffeine use for CE, we did not specifically ask about the use of coffee, caffeinated drinks, or caffeine tablets immediately before surgical interventions. Future research in the field should provide data to which amount the use of caffeine occurred in the OR with the aim to increase cognitive skills.