Volume 29-24
15 December 2003

[Table of Contents]

UPDATE - SURVEILLANCE OF HEALTH CARE WORKERS EXPOSED TO BLOOD, BODY FLUIDS AND BLOODBORNE PATHOGENS IN CANADIAN HOSPITAL SETTINGS: 1 APRIL, 2000, TO 31 MARCH, 2002  

The Canadian Needle Stick Surveillance Network (CNSSN) has been implemented since 2000 to monitor health care workers (HCWs) exposed to blood and body fluids and their subsequent seroconversion as a result of the exposure. As part of the surveillance program, Health Canada and a network of volunteer hospitals across Canada have collaborated to develop a registry of exposed HCWs. In this report, we present data collected between 1 April, 2000, and 31 March, 2002. 

Methods 

The characteristics of 12 volunteer hospitals and the collaborative study design have been described in a previous article⁽¹⁾. Briefly, information on the exposure, source patient and follow-up of exposed HCWs is collected on standardized forms and is sent anonymously to Health Canada every 6 months. Included in this information are exposures to blood and body fluids (BBF) such as blood, serum, plasma, saliva, sperm, and vaginal secretions; amniotic, cerebrospinal, pleural, pericardial, peritoneal, and synovial fluid; and other fluids visibly stained with blood. Bloodborne pathogens (BBP) include hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV. Exposures considered to carry a risk of BBP transmission are percutaneous (needle sticks, cuts, scratches, bites) and mucocutaneous (contacts with mucous membranes or with non-intact skin).

Exposures reported from 1 April, 2000, to 31 March, 2002, were selected for analysis. Rates according to the number of full-time employee equivalents (FTEs), patient admissions, patient beds and patient days were calculated using SAS 8.1 (SAS Institute, Cary, NC). Where appropriate, chi-square tests for statistical differences were completed. Administrative employees did not contribute to the number of FTEs since they were unlikely to be exposed to patient blood or body fluids. Because hospitals varied in how they recorded their work force, it was decided to group medical specialists and medical residents as medical doctors; other physicians as general practitioners; and phlebotomists and clinical laboratory technicians as laboratory technicians.

Results 

Exposures to BBF 

During the 24-month observation period (18 months in the case of one site), the 12 participating sites reported 17 174 available beds, 509 312 admissions, 4 604 329 patient-days, 68 429 FTEs and 2621 occupational exposures to BBF. Of these exposures, needle sticks accounted for 65.7%, splashes from patients 13.7%, cuts with sharp objects 8.6%, sticks other than needle sticks 7.2%, scratches 1.9%, touching patients directly 1.8%, and bites 1.2%. Blood or blood derivatives were involved in 82.5% of the exposures and saliva stained with blood in 3.0%.

The overall rates of exposure to BBF were 15.3/100 beds, 3.8/100 FTEs, 0.06/100 patient days or 0.5/100 patient admissions. Table 1 summarizes the rates (per 100 FTEs) by type of exposure and job title. Nurses, medical doctors, and laboratory technicians were the three professional groups that most frequently reported exposures (52.6%, 12.6%, and 9.4%, respectively). The highest percutaneous exposure rates were observed among medical doctors (10.4), nuclear medical technicians (8.1), and sterilization attendants (8.1). The highest mucocutaneous exposure rates were observed among inhalation therapists (1.5), medical students (1.4) and other
technicians (1.1). 

Of the percutaneous exposures, two-thirds were caused by hypodermic needles, suture needles, winged needles, venous catheter needles, and blood collection needles (used for blood drawing as well as injections and sutures). Injuries caused by the last three devices carried a greater risk of BBP transmission since these needles contained more blood than the first two devices (64.4%, 84.5%, 95.1% versus 11.2% for hypodermic needles and 0% for suture needles). Furthermore, 78.1% of percutaneous injuries were penetrating, i.e. they involved moderate-to-deep broken skin with or without bleeding. The circumstances that led to percutaneous injuries are summarized in Table 2. Almost half of the injuries occurred after the device had been used, for example, 24.2% occurred after use but before disposal of sharps, 12.0% were related to the collection/containment of sharps, and 9.0% were related to disposal activities.

Regarding mucocutaneous exposures, 70.5% occurred on mucous membranes and 22.3% on non-intact skin. The exposures were primarily characterized as arising from splashes directly from patients (45.5%), defective equipment (26.0%), and direct contact with patients (6.4%). Eyes were the most common areas of exposure, followed by index and major fingers. One-third of the exposures occurred when the worker was not wearing protective clothing. 

Exposures to BBP 

In this study, source patients were identified for 85.3% of the 2621 exposures. Test results from the identified sources screened for BBP showed that 7.6%, 2.6% and 1.8% of them were infected with HCV, HIV, or HBV respectively, and 16.9% (35 source patients) had co-infections: 27 with HCV-HIV, four with HBV-HCV, one with HBV-HIV, and three with HBV-HCV-HIV.
 

Table 1 shows the rates (per 100 FTEs) of exposure to BBP by type of exposure and job title. The overall exposure rate was 0.3 (0.2 for percutaneous and 0.1 for mucocutaneous). Nurses, medical doctors, and laboratory technicians were the three professional groups that most frequently reported exposures (53.4%, 21.3%, 8.2%). However, medical doctors reported both the highest percutaneous exposure rate and the highest mucocutaneous exposure rate to BBP. 

Regarding the serologic status of exposed HCWs, 97.0% of workers (32/33) exposed to HBV stated that they had been vaccinated against HBV, 69.7% confirmed that they had proof of immunity, and 57.6% were documented as being seroprotected against HBV (i.e. anti-HBs levels of $10 IU/L) at the time of exposure. For HCV, three workers (2.3%) were already positive for anti-HCV at the time of exposure, yielding a prevalence of 1.4% among HCWs. The 6-month follow-up rates among HCWs exposed to sources positive for HBV, HCV, and HIV were 0%, 36.5%, and 20.3%, respectively. To date, no HCW has seroconverted as a result of the exposure. 

Table 1    Rates of exposure to BBF (blood and body fluids) and BBP (bloodborne pathogens) per 100 FTEs (full-time employee equivalents) by job title and type of exposure, 12 hospitals, 2000-2002

*    Includes 1960 days of follow-up among community health nurses. 

Table 2    Circumstances leading to percutaneous exposures (n = 2185), 12 hospitals, 2000-2002 

Discussion 

The CNSSN provides baseline information from 12 participating hospitals. From these selected hospitals, the overall rate of exposure to BBF was 3.8 per 100 HCWs, and the rate of exposure to BBP was 0.3 per 100 HCWs for the 2-year period. The prevalence of HCV was much higher than the prevalence of HIV and HBV among identified and tested source patients (7.6% versus 2.6% and 1.8%). This finding is quite different from the rates found among patients admitted to a Toronto hospital in1990⁽²⁾, which were 0.5% for HCV, 0.6% for HIV, and 2.1% for HBV. 

Coupled with the high HCV prevalence, the substantial proportion of patients in this study who were infected with more than one virus is worrisome. The co-infection situation is more likely to put HCWs at risk of acquiring bloodborne infections and complicates further the post-exposure management of HCWs exposed to infected sources. The study identified those employees at high risk of exposure to BBF and BBP (medical doctors, laboratory technicians, nuclear medical technicians, sterilization attendants, inhalation therapists, and medical students) as well as the procedures (handling and disposal of used needles) and devices (blood drawing needles) that carried a high risk of BBP transmission. Interventions to reduce occupational exposures to BBF and BBP need to be tailored to these subgroups. 

The findings presented here are subject to a few limitations. First, they are not representative of all Canadian hospitals because of site self-selection and reporting biases inherent with a voluntary registry. Second, it is impossible to know whether the same HCW had multiple exposures during the 2-year period, given that the database is exposure- rather than employee-based. Third, in the majority of participating hospitals, injuries to physicians, medical students, phlebotomists or others who are not employed by the hospital might not show up in hospital records. For other groups, such as medical residents or occasional employees, it may not be easy to obtain reasonable FTEs for a denominator. The lack of reliable numerators and denominators for certain occupational categories makes the calculation of specific rates challenging. Finally, follow-up data of HCWs exposed to virus-positive patients are incomplete as a result of some difficulties with coordination and data collection across departments. Continued surveillance of occupational exposures is essential. More data will help us better understand the situation in Canadian hospitals and provide the evidence required for informed decisions.
 

Note 

The Blood Safety and Health Care Acquired Infections Division, Centre for Infectious Disease Prevention and Control, plans to expand the surveillance network to more sites. Hospitals interested in collecting these data are encouraged to contact Mai Nguyen, Nurse Epidemiologist, telephone: (613) 946-0169; fax: (613) 998-6413; E-mail: mai_nguyen@hc-sc.gc.ca. 

Acknowledgments 

We gratefully acknowledge the following sites, which contributed data to the CNSSN: Capital Health Region (B.C.); St-Paul's Hospital (B.C.); Stanton Regional Health Board (N.W.T.); Calgary Health Region (Alta.); Moose Jaw-Thunder Creek District Health Board (Sask.); St-Boniface General Hospital (Man.); Welland County General Hospital (Ont.); Health Science Centre (Ont.); St-Joseph's Hospital (Ont.); South East Health Care (N.B.); Cape Breton Health Care Complex (N.S.); and the Queen Elizabeth Hospital (P.E.I.).

References 

1. Nguyen M, Paton S, Villeneuve P. Update - surveillance of health care workers exposed to blood/body fluids and bloodborne pathogens: 1 April, 2000, to 31 March, 2001. CCDR 2001;27(24):201-12. 

2. Louie M, Low DE, Feinman SV et al. Prevalence of bloodborne infective agents among people admitted to a Canadian hospital. Can Med Assoc J 1992;146:1331-34. 

Source:    M Nguyen, MSc, S Paton, MN, RN, J Koch, BSc, Nosocomial and Occupational Infections Section, Blood Safety Surveillance and Health Care Acquired Infections Division, Public Health Agency of Canada, Health Canada. 

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