Occupational Exposures to Body Fluids among Medical Students: A Seven-Year Longitudinal Study

Medical students may be vulnerable to accidental exposures to blood because they lack experience and skill, even though they are eager to learn new procedures (1-7). The risk for exposure to and infection by bloodborne pathogens among medical students is not known, and published reports probably underestimate the actual risk because many exposures are not reported. Health care workers, especially physicians in training (2, 4, 6), often do not report exposures because of fear of losing insurance and employment, disbelief in the efficacy of prophylaxis, or a tendency to deny personal risk. Early in the course of the AIDS epidemic, the University of California, San Francisco, recognized the potential risk for exposure among medical students, and it implemented curricular changes to encourage universal precautions and the safer use of needles during bedside procedures. It also created a comprehensive postexposure care system, including needlestick hotlines, to facilitate reporting of exposures at the teaching hospitals affiliated with the University of California, San Francisco, for all health care workers, including students. However, surveys of graduating students showed that many accidental exposures occurred despite the training given. Our study was done to 1) identify factors associated with occupational exposure that might be modified to protect medical students from unnecessary risk and 2) describe the epidemiology of occupational exposures sustained by medical students at the University of California, San Francisco, over a 7-year period. Methods We hypothesized that the following variables might be associated with the probability of occupational exposure to blood: type of clerkship, previous completion of a clerkship in an area suspected of conferring a high risk for occupational exposure (obstetrics [2], surgery [3], or medicine [4-6]), and year of graduation (7). All occupational exposures reported by medical students who graduated from the University of California, San Francisco, School of Medicine between 1990 and 1996 were retrospectively reviewed. Eligible exposures were only those reported between June 1989 and May 1996. Exposures occurred through needle punctures, lacerations, and other injuries caused by sharp objects; mucosal splashes; and contact of nonintact skin with blood or bloody body fluids. Data Collection Occupational exposures were initially reported to needlestick hotlines, which are managed by employee health services, at the hospitals affiliated with the University of California, San Francisco. In 1989, San Francisco General Hospital instituted the first hotline, through which housestaff, students, staff, and faculty could report occupational exposures. In June 1990, similar programs were implemented at all of the other hospitals in San Francisco that are affiliated with the University of California, San Francisco: Moffitt-Long Hospital, the Veterans Affairs Medical Center, and Mt. Zion Hospital. These hotlines were endorsed by the Chancellor's AIDS Coordinating Committee at the University of California, San Francisco, and were designed to be anonymous, available 24 hours a day, and staffed by experts in exposure management. Students were encouraged to report injuries to the hotline service closest to them. During their orientation to clerkships, students received pocket-sized laminated cards printed with the telephone numbers of the hotlines at the various hospitals. These cards were also given to all new housestaff and were prominently displayed in emergency departments, nursing stations, and resident lounges at all hospitals. Students who reported an exposure to the hotline received baseline and follow-up care at the employee health services on the campus where the exposure occurred. Students could report occupational exposures to the Student Health Service before 1991, but after this date, the hotlines were available at all sites and all exposed students were managed by employee health services. Thus, this study used data derived from the employee health services hotlines. The clerkship schedules for each eligible medical student were provided by the Office of Student and Curricular Affairs to a statistician who had no access to reported exposure data. This statistician assigned each student a study identification number from a table of random numbers. The list of all students and their identification numbers was then forwarded to the clinical personnel responsible for the treatment and surveillance of occupational exposures at the hospitals affiliated with the University of California, San Francisco. The clinicians (who already knew the names of exposed students because they provided postexposure clinical care) extracted relevant data, including exposure history, type of exposure, and the results of baseline and follow-up tests for bloodborne viruses, from the student's confidential exposure record. No other data on exposures were available from the student health service or other providers. The exposure data were linked to the students' identification numbers in a computer database. To maintain confidentiality, the clinicians then deleted the student names from the database and returned the exposure data to the study personnel without including personal identifiers. The protocol for this study was approved by the University of California, San Francisco, Committee on Human Research. School of Medicine Curriculum All medical students at the University of California, San Francisco, School of Medicine are required to participate in the same 10 core clerkships (totaling 52 weeks) during the third and fourth years of medical school. Eight of these clerkships are in anesthesia, family and community medicine, obstetrics-gynecology, medicine, neurology, pediatrics, psychiatry, and surgery and surgical specialties; 1 is a medicine subinternship; and 1 is another subinternship in which the student has primary responsibility for patient care (more than two thirds of students elect to take emergency medicine). Schedules are determined by lottery, and the sequence and location of clerkships vary widely. All students in the years studied rotated through all four of the San Francisco hospitals affiliated with the University of California, San Francisco. Training in Exposure Prevention In June 1989, the University of California, San Francisco, implemented a requirement that all third-year medical students be trained in universal precautions and exposure prevention as a component of a 1-week introduction to clerkships. First conceived to provide clinical skills and training in universal precautions, this program has evolved into a mini-course intended to improve the experience and performance of third-year medical students in clerkships. The course is taught by clinical faculty and fourth-year medical students. Through lectures; small group seminars; panel discussions; and hands-on practice with phlebotomy, intravenous catheter insertion, arterial blood sampling, and blood culture techniques, students learn the essentials of bedside clinical procedures in a safe, low-stress environment. All students watch the same videotape and hear discussions about universal precautions and exposure prevention provided by occupational health and infection control nurses. Since 1993, this course has also included hands-on instruction in the use of safer needle devices for phlebotomy and intravenous catheter insertion. Each year, the students rate the course as excellent. Assessment of Underreporting Previous investigators (2, 4, 6) have established that occupational exposures among housestaff and medical students are substantially underreported. We hypothesized that the needlestick hotlines would increase the rate of reporting once students became comfortable with these confidential services. To estimate the degree of underreporting, we conducted anonymous surveys of medical students to ascertain the number of exposures sustained and the proportion of exposures reported to the hotlines. Students in the class of 1991 were queried in the winter of 1990 (just as the needlestick hotline was implemented), and students in the class of 1996 were queried just before graduation in June 1996. The anonymous questionnaires were distributed by the Office of Curricular Affairs. Statistical Analysis The proportion of exposed students was defined as the number of students reporting one or more exposures divided by the number of students enrolled at the University of California, San Francisco, School of Medicine during the study period. For each student who had multiple exposures, one exposure was chosen by using a table of random numbers to avoid the possibility of bias toward students who reported or sustained more exposures. Categorical data were compared by using the chi-square test. Comparisons with a P value less than 0.05 (two-tailed) were considered statistically significant. Results One thousand twenty-two medical students were enrolled in the University of California, San Francisco, School of Medicine classes of 1990 through 1996 (Table 1). Of these students, 119 (11.7% [95% CI, 9.0% to 15.2%]) reported one or more occupational exposures to the needlestick hotlines. Only 10 students (2%) reported two exposures. Most occupational exposures were caused by needle punctures (Table 2). Table 1. Graduation Year and Graduating Class Size of Students Who Reported Occupational Exposures Table 2. Types of Occupational Exposures Sustained by Medical Students Infections with Bloodborne Pathogens This study was not designed to evaluate the incidence of infection with bloodborne pathogens, but no students who reported eligible exposures were known to have acquired HIV, hepatitis C virus (HCV), or hepatitis B virus (HBV) infection. In 1993, the medical school purchased disability insurance for all students to provide coverage for occupational infections. After 4 years of experience with the same insurance broker, no disability clai