Penny S. McKibben

A case-control study of HIV seroconversion in health care workers after percutaneous exposure

BACKGROUND The average risk of human immunodeficiency virus (HIV) infection after percutaneous exposure to HIV-infected blood is 0.3 percent, but the factors that influence this risk are not well understood. METHODS We conducted a case-control study of health care workers with occupational, percutaneous exposure to HIV-infected blood. The case patients were those who became seropositive after exposure to HIV, as reported by national surveillance systems in France, Italy, the United Kingdom, and the United States. The controls were health care workers in a prospective surveillance project who were exposed to HIV but did not seroconvert. RESULTS Logistic-regression analysis based on 33 case patients and 665 controls showed that significant risk factors for seroconversion were deep injury (odds ratio= 15; 95 percent confidence interval, 6.0 to 41), injury with a device that was visibly contaminated with the source patients blood (odds ratio= 6.2; 95 percent confidence interval, 2.2 to 21), a procedure involving a needle placed in the source patients artery or vein (odds ratio=4.3; 95 percent confidence interval, 1.7 to 12), and exposure to a source patient who died of the acquired immunodeficiency syndrome within two months afterward (odds ratio=5.6; 95 percent confidence interval, 2.0 to 16). The case patients were significantly less likely than the controls to have taken zidovudine after the exposure (odds ratio=0.19; 95 percent confidence interval, 0.06 to 0.52). CONCLUSIONS The risk of HIV infection after percutaneous exposure increases with a larger volume of blood and, probably, a higher titer of HIV in the source patients blood. Postexposure prophylaxis with zidovudine appears to be protective.Background The average risk of human immunodeficiency virus (HIV) infection after percutaneous exposure to HIV-infected blood is 0.3 percent, but the factors that influence this risk are not well understood. Methods We conducted a case–control study of health care workers with occupational, percutaneous exposure to HIV-infected blood. The case patients were those who became seropositive after exposure to HIV, as reported by national surveillance systems in France, Italy, the United Kingdom, and the United States. The controls were health care workers in a prospective surveillance project who were exposed to HIV but did not seroconvert. Results Logistic-regression analysis based on 33 case patients and 665 controls showed that significant risk factors for seroconversion were deep injury (odds ratio = 15; 95 percent confidence interval, 6.0 to 41), injury with a device that was visibly contaminated with the source patients blood (odds ratio = 6.2; 95 percent confidence interval, 2.2 to 21), a procedure inv...

Surveillance of HIV Infection and Zidovudine Use among Health Care Workers after Occupational Exposure to HIV-Infected Blood

Health care workers are at risk for human immunodeficiency virus (HIV) infection after an occupational exposure to blood, certain other body fluids, and tissue from an HIV-infected patient [1, 2]. Zidovudine has been used after exposure to reduce this risk, despite the lack of data on efficacy and limited data on toxicity when used for this purpose [3-5]. In 1983, the Centers for Disease Control and Prevention (CDC) began a national voluntary surveillance project to estimate the risk for HIV transmission after a single exposure to HIV-infected blood [6]. In October 1988, the project was expanded to collect information describing the use of postexposure zidovudine among enrolled workers. In this update of the ongoing surveillance project, we focus on the patterns of use and associated toxicity of postexposure zidovudine use among enrolled workers and report the failure of zidovudine to prevent HIV infection in one worker. Methods CDC Surveillance Project The surveillance project has been described previously [6, 7]. In brief, workers in a group of participating health care institutions throughout the United States are voluntarily enrolled by cooperating investigators after an exposure to blood from a patient with documented HIV infection as a result of percutaneous injury (for example, a needlestick or a cut from a sharp object), contamination of mucous membranes, or contamination of nonintact skin. (Extensive or prolonged blood contact with intact skin may constitute an occupational exposure [4], but workers with intact skin exposures are not enrolled in this project.) Epidemiologic information and a blood specimen for HIV serologic testing are collected by the cooperating investigator at a baseline visit within 1 month after exposure and at follow-up visits 6 weeks, 3 months, 6 months, and 1 year after exposure. At enrollment, workers complete and mail directly to the CDC an anonymous questionnaire that includes information on nonoccupational risk factors for HIV infection. Workers who seroconvert are interviewed in person by an investigator using a standard CDC protocol for the interview of persons with no identified risk. Human immunodeficiency virus serologic testing is done either at the CDC or at the cooperating institutions laboratory, with all positive results confirmed at the CDC. Use of Postexposure Zidovudine In October 1988, the surveillance project was expanded to collect additional information on the postexposure use and toxicity of antiviral agents, such as zidovudine. A standardized protocol for offering or using postexposure zidovudine was not provided by the CDC; in accordance with the Public Health Service statement [4], individual cooperating investigators and exposed workers determined whether postexposure zidovudine would be used, and, among those using zidovudine, the dosage and duration of prophylaxis. Adverse Events At the 6-week follow-up visit, the cooperating investigators were asked to record reported symptoms on a standardized checklist provided by the CDC, as well as the zidovudine regimen, if used. In this surveillance project, a standard protocol for laboratory testing for adverse effects (for example, anemia) of zidovudine was not provided by the CDC; such tests were done at the discretion of the cooperating investigator, who recorded the test date and any results outside the testing laboratorys normal range. Statistical Analysis Data were analyzed using PRODAS (Conceptual Software, Houston, Texas), Epi-Info (CDC, Atlanta, Georgia), and the Statistical Analysis System (SAS Institute, Inc., Cary, North Carolina). The upper bounds of the 95% CI were calculated using the binomial distribution. Because of missing data, totals for specific analyses may not equal the total number of enrolled workers. Results From August 1983 through June 1992, 1245 workers from 312 institutions were enrolled and tested for HIV antibody at baseline and at least 180 days after exposure. These workers comprised nurses (64%), physicians and dentists (12%), phlebotomists (8%), laboratory workers (6%), medical students (2%), housekeepers (1%), and other workers (such as technicians and physician and nursing assistants) (8%). Exposures to HIV-infected Blood and Risk for HIV Infection A total of 1245 workers were enrolled and tested for HIV antibody at baseline and at least 180 days after exposure. These workers had been exposed to blood from source patients who had AIDS as defined by the CDC surveillance case definition in use at the time of enrollment, (1012 [81%] exposures) [8], who were HIV-antibody positive and symptomatic but who did not have AIDS (68 [5%] exposures), or were HIV-antibody positive and asymptomatic (165 [13%] exposures). Exposure types were percutaneous injury (1103; 89%) and blood contact with mucous membranes (67; 5%) or nonintact skin (75; 6%). The 1103 percutaneous injuries were caused by syringe needles (375; 34%), intravenous needles (343; 31%), suture needles (41; 4%), and other needles (228; 21%); scalpels (41; 4%); lancets (27; 2%); and other sharp objects (48; 4%). Among 1103 workers with percutaneous injuries who were HIV seronegative at baseline, 4 (0.36%; upper limit CI, 0.83%) seroconverted to HIV. Among workers with percutaneous injury, the seroconversion rate after exposure to blood from source patients with AIDS was 0.44% (4 of 899; upper limit CI, 1.01%); the seroconversion rate was not statistically different after exposure to blood from source patients who were HIV-antibody positive and symptomatic but who were without AIDS (0 of 57, P > 0.2) or source patients who were HIV-antibody positive and asymptomatic (0 of 147, P > 0.2). No seroconversions occurred among workers with blood exposure of mucous membranes (67 workers; upper limit CI, 4.31%) or skin (75 workers; upper limit CI, 3.87%). An additional 497 workers enrolled in the early 1980s, before HIV-antibody testing was available, were tested for HIV antibody at least 180 days after exposure but not at baseline. One of these workers was HIV-antibody positive when first tested 10 months after exposure [7]. At that time, a sex partner of this worker was also tested and found to be HIV seropositive; the dates of HIV infection for this worker and partner are unknown. Including these 497 workers, the HIV seroprevalence rate was 0.32% (5 of 1532; upper limit CI, 0.68%) after percutaneous exposure, 0% (0 of 100; upper limit CI, 2.9%) after mucous membrane exposure, and 0% (0 of 110; upper limit CI, 2.7%) after skin exposure to HIV-infected blood. Of the four workers enrolled in this project who have seroconverted after exposure to HIV, three have been previously described [6, 7]. The fourth worker, a female laboratory worker, was injured in 1992 by a 21-gauge syringe needle after doing a phlebotomy on a patient who was known to have AIDS. The worker reported no behavioral risk factors for HIV infection, except for having had sexual contact with a person at risk for HIV infection more than 1 year before her injury. The worker began taking zidovudine 2 hours after the injury, in a dose of 100 mg, five times a day, for the first day and then 200 mg, five times per day, for 16 additional days (Table 1, report 5). The worker discontinued use of zidovudine after 17 days because of nausea, fatigue, and myalgia. Thirty-eight days after exposure, the worker developed fever, malaise, fatigue, nausea, arthralgia, myalgia, and rash. Serologic test results for HIV were negative for specimens of the workers blood collected on the day of the injury and 6 weeks afterward, were indeterminate by enzyme immunoassay and positive by Western blot 3 months after injury, and were positive by both enzyme immunoassay and Western blot 4 months after injury. The source patient was not known to have received zidovudine before the needlestick incident. Table 1. Reported Instances of Failure of Postexposure Zidovudine To Prevent HIV Infection in Health Care Workers after Percutaneous Exposure to HIV-infected Blood To determine whether the worker was infected with zidovudine-resistant virus, peripheral blood mononuclear cells were collected from the worker and the source patient 3 months and 8 months after exposure, respectively. At the Walter Reed Army Institute of Research (Washington, D.C.), cells from the worker were positive for HIV-1 using the polymerase chain reaction (PCR), but efforts to isolate the virus for phenotypic zidovudine-susceptibility testing were not successful. Nested PCR to detect mutations in the HIV reverse transcriptase at amino acid position 215 associated with zidovudine resistance did not show alterations at that site in peripheral blood mononuclear cells from either worker or source patient [9] (D. Mayers. Personal communication). At the CDC, direct sequencing of the HIV-1 reverse-transcriptase gene (amplified by PCR from the workers peripheral blood mononuclear cells [10]) showed no mutations at position 215 or at the four other amino acid positions (positions 41, 67, 70, and 219) known to be associated with zidovudine resistance [11, 12] (data not shown). Use of Postexposure Zidovudine From October 1988 to June 1992, the period when use of zidovudine was studied, 848 workers were enrolled. Postexposure zidovudine was used by 265 (31%) of these workers. Of 200 cooperating investigators who enrolled workers during this period, 110 (55%) reported that at least one worker used zidovudine. Zidovudine was prescribed in doses ranging from 200 to 1800 mg/d (median, 1000 mg/d) and for periods of 1 to 180 days (median, 42 days). The interval from exposure to first dose of zidovudine ranged from less than 5 minutes to 17 days (median, 4 hours). No clinically significant changes in prescribed regimens of zidovudine were seen during the study period (data not shown). The proportion of enrolled workers using zidovudine increased from 5% in the fourth quarter of 1988 to 50% in the third quarter of 1990 and has been stable subseq

Skin and mucous membrane contacts with blood during surgical procedures: risk and prevention.

OBJECTIVE To study the epidemiology and preventability of blood contact with skin and mucous membranes during surgical procedures. DESIGN Observers present at 1,382 surgical procedures recorded information about the procedure, the personnel present, and the contacts that occurred. SETTING Four US teaching hospitals during 1990. PARTICIPANTS Operating room personnel in five surgical specialties. MAIN OUTCOME MEASURES Numbers and circumstances of contact between the patients blood (or other infective fluids) and surgical personnels mucous membranes (mucous membrane contacts) or skin (skin contacts, excluding percutaneous injuries). RESULTS A total of 1,069 skin (including 620 hand, 258 body, and 172 face) and 32 mucous membrane (all affecting eyes) contacts were observed. Surgeons sustained most contacts (19% had > or = 1 skin contact and 0.5% had > or = 1 mucous membrane-eye contact). Hand contacts were 72% lower among surgeons who double gloved, and face contacts were prevented reliably by face shields. Mucous membrane-eye contacts were significantly less frequent in surgeons wearing eyeglasses and were absent in surgeons wearing goggles or face shields. Among surgeons, risk factors for skin contact depended on the area of contact: hand contacts were associated most closely with procedure duration (adjusted odds ratio [OR], 9.4; > or = 4 versus < 1 hour); body contacts (arms, legs, and torso) with estimated blood losses (adjusted OR, 8.4; > or = 1,000 versus < 100 mL); and face contacts, with orthopedic service (adjusted OR, 7.5 compared with general surgery). CONCLUSION Skin and mucous membrane contacts are preventable by appropriate barrier precautions, yet occur commonly during surgery. Surgeons who perform procedures similar to those included in this study should strongly consider double gloving, changing gloves routinely during surgery, or both.

Occupational Blood Contact Among Prehospital Providers

STUDY OBJECTIVE To assess the nature and frequency of blood contact (BC) among emergency medical service (EMS) workers. DESIGN During an 8-month period, we interviewed EMS workers returning from emergency transport calls on a sample of shifts. We simultaneously conducted an HIV seroprevalence survey among EMS-transported patients at receiving hospitals served by these workers. SETTING Three US cities with high AIDS incidence. PARTICIPANTS EMS workers. RESULTS During 165 shifts, 2,472 patients were attended. Sixty-two BCs (1 needlestick and 61 skin contacts) were reported. Individual EMS workers had a mean of 1.25 BCs, including .02 percutaneous exposures, per 100 patients attended. The estimated annual frequency of BC for an EMS worker at the study sites was 12.3, including .2 percutaneous exposures. For 93.5% of the BCs, the HIV serostatus of the source patients was unknown to the EMS worker. HIV seroprevalences among EMS-transported patients at the three receiving hospital emergency departments were 8.3, 7.7, and 4.1 per 100 patients; the highest rates were among male patients 15 to 44 years old who presented with pneumonia. CONCLUSION EMS personnel regularly experience BCs, most of which are skin contacts. Because the HIV serostatus of the patient is usually unknown, EMS workers should practice universal precautions. Postexposure management should include a mechanism for voluntary HIV counseling and testing of the patient after transport and transmittal of the results to the EMS.