Hollow-bore needlestick injuries in a tertiary teaching hospital: epidemiology, education and engineering

The recognition in the 1980s of the potential transmission of bloodborne viruses to healthcare workers through needlestick injury (NSI) led to a universal focus on the prevention of such incidents.1-3 The frequency and nature of injury with dirty hollow-bore needles experienced by healthcare workers in Australian hospital practice were last published almost a decade ago.1,2 More recently, media concern has turned to the dangers of injuries to members of the public due to discarded needles. Although there is intense lay and political concern over community-acquired NSI, these injuries are uncommon and regarded as lower risk than those sustained by healthcare workers.4,5

We describe the rate of reporting and nature of exposure over the past decade from hollow-bore dirty needles in healthcare workers in a tertiary referral hospital. We have also assessed the benefits and consumables cost of widespread introduction of safety devices into the hospital.

Princess Alexandra Hospital, Brisbane, is an 800-bed university tertiary referral teaching hospital. Prospective data on staff, self-reported to the infection control service since 1987 as part of the hospital's NSI follow-up protocol, detail percutaneous exposures, including "clean" and "dirty" (ie, injury with a used sharp) NSI and body fluid. Initially, these data were collated and analysed manually, and subsequently with software packages: NOSO 3 (1990–1993),6 Q Logic (1994–1995)7 and EpiNet (1996–1999).8 Variables within the database for these periods remained essentially unchanged. We excluded body fluid exposures and "clean" NSI, as they pose a low or nil risk, respectively, of bloodborne virus transmission. Staff have been grouped into three classes: clinical (nursing, medical); those at risk of "downstream" injury (housekeeping, catering, wardsmen, Central Sterilizing Supply Department laundry); and other staff (phlebotomists, paramedical, laboratory).

Standardised, anonymous questionnaire surveys in convenience samples of nursing staff were also undertaken throughout the surveillance period at about three-year intervals to determine both the true reporting rate of dirty NSI in this occupational group and their knowledge of potential disease transmission.

Frequencies, rates and proportions were calculated using SPSS for Windows.9 Epi Info10 was used to calculate 95% confidence intervals around proportions, ?2 for trend and Fisher exact tests for significance. Annual rates of NSI were calculated using the number of full-time-equivalent (FTE) positions for each year as denominator. FTEs were provided by the hospital's finance department, and were calculated for each staff category as the mean of the number of FTE positions at the end of each financial year of the study period. We assumed that significant fluctuations in the number of FTEs due to annual leave or changes in staffing levels did not occur.

The only similar Australian study published reported a rate of 9.4/100 FTE per year in nursing staff,1 similar to our hospital's mean rate of 8.79/100 FTE per year in nursing staff over the 10-year survey period (1990–1999). Only one overseas study12 is comparable, as it too followed NSI rates in a single institute after multifocused interventions. The researchers assessed NSI rates per FTE per year over an eight-year period (1990–1998).12 Hollow-bore NSI in all healthcare workers, excluding physicians (who were not assessed), declined from 65/100 FTE per year to 16/100 FTE per year. However, even this improved rate of 16/100 FTE per year is more than twofold higher than that reported previously in Australia1 and in our study.

Although non-hollow-bore sharps injuries constitute a significant proportion of incidents (34.7%), interventions to prevent NSI have focused on hollow-bore needles, which were the most frequent source of NSI and pose the greatest risk of bloodborne virus transmission.13 Orientation and reinforcement education sessions were conducted over the entire survey period. Additionally, awareness and "ownership" were facilitated by competitions held to develop educational posters that were subsequently displayed in all clinical areas. Physical interventions included introduction of a recapping device11,14 (1987) to allow safe recapping as an alternative to immediate disposal; positioning of approved "sharps" bins in areas of clinical activity and on trolleys wheeled to the bedside to facilitate immediate needle disposal15,16 (1989); and introduction of a commercial closed disposal system with sealed containers removed from the hospital by contractors (1989). Safety intravenous cannulas were introduced into the emergency department and operating theatre suite in 1994, but not more widely. The hospital has not used a needleless intravenous (IV) system during the past 15 years, except in the operating theatres from 1995 onwards.

Certain areas of improvement have been identified, including reduction in recapping11 and increasing knowledge in nurses of the possible outcome of bloodborne virus infection. However, the NSI rate per year at Princess Alexandra Hospital (PAH) has not declined over the past decade. The overall increase in the total reported rate may be artificial. It might be explained by better reporting of NSI by medical staff (Box 1), whose rate of NSI as an occupational group now exceeds that of nurses. In contrast, repeated anonymous surveys of nurses suggest that their rate of reporting dramatically improved to the early 1990s. Since then, a constant 76%–96% of the true rate has been maintained for the rest of the decade (Box 3).

The reduction in hazard achieved from better equipment design is pivotal to improvement in safety and quality in all areas of healthcare facilities.17,18 While our study has demonstrated an increased knowledge and awareness of the consequences of NSI in nurses, a high endemic level of NSI continues (Box 1). Further improvement in NSI safety is likely to come not from low cost educational programs, but from engineering.19 The benefits of safer devices over behaviour modification have been widely debated,17,20 and culminated in 1999 in the United States with the passage of the Needlestick Injury Safety and Prevention Act 2000.21 This requires the bloodborne virus exposure control plans of US hospitals to "reflect changes in technology that eliminate or reduce the exposure to blood borne pathogens". Multiple safety devices have been developed and variable effects reported.22-26 All the devices are more expensive than those they replace, and thus their widespread introduction carries significant economic cost. The benefits and limitations of such interventions need careful assessment against the background epidemiology of percutaneous exposures within a given healthcare setting.

Our study indicates that 127 (6.9%) of reported dirty NSI at PAH over a decade were associated with a risk of bloodborne virus acquisition. No seroconversion was detected, but, with the low risk of transmission associated with a single exposure,27 this outcome was not unexpected. Most healthcare workers are particularly concerned about exposure to HIV. However, while dependent on the background carriage rate of bloodborne virus in a facility's patient population, our experience indicates that Australian healthcare workers are at greatest risk of HCV infection, a disease for which no proven effective prophylaxis exists.

Our data suggest that the introduction of syringes with self-retracting needles could reduce high-risk NSI in our hospital by up to 62%. These devices incorporate automatic retraction of the needle into the barrel of the syringe, provided the user depresses the plunger to the end of the barrel. As this is the normal action when expelling the contents of a syringe, regardless of purpose, it is likely to be carried out without conscious intent. Butterfly needles have again been associated with significant risk of NSI to healthcare workers.2,28 While protective shielded butterfly needles have been shown to reduce NSI in one trial,29 they require conscious manipulation of a sheath over the needle at the end of a procedure. There is a need for constant educational reinforcement when using these devices,29 and this does not augur well for their long term effectiveness in routine clinical practice. Replacement of non-shielded butterfly needles, where practicable, with self-retracting syringes could further reduce NSI by up to 10%.

The crude estimated extra cost per year at Princess Alexandra Hospital for syringes with self-retracting needles at $0.65 per unit is $365 000. This figure is conservative, not taking into account indirect savings from reduction in loss of staff time associated with NSI assessment and follow-up, decreased consumables for laboratory testing of staff and patients, and the intangible benefits of reduced staff anxiety.30 Our estimate is not intended to represent a formal cost–benefit analysis, but simply the likely funding necessary to implement purchase of consumables.

Our data show that, at one tertiary referral hospital, more than one potentially high-risk NSI occurs for every two days of hospital operation. Hospital administrators have been shown to be tolerant of a finite NSI rate, although the acceptable threshold varies with their awareness and knowledge of the issue.31 It is they who must determine whether the budgetary implications of protective devices are justified by the potential reduction in these exposures. This is not the case in the US, where legislation was introduced without consideration of either its financial impact on individual healthcare facilities, or the differing impacts of varying safety devices on reduction of high-risk exposure. Such a situation should not be allowed to occur in Australia. Introduction of safety devices should not simply be an emotional response to heathcare worker concerns, but must be shown to have proven efficacy and must be accompanied by a cost-containment strategy. Only well-designed clinical trials can provide these data.