Skip navigation

HIV seroconversion after needlestick injury

 

Clinical bottom line

Seroconversion after percutaneous exposure to blood is more likely if the injury was deep, the needle was visibly contaminated with the source patient's blood, the needle was in the source patient's artery or vein, and if the patient died of AIDS within two months. Patients who seroconverted were less likely to have received post-exposure anti-viral agents.


Reference

DM Cardo et al. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. New England Journal of Medicine 1997 337: 1485-90.

Study

This was a case-control study in which the case patients were healthcare workers with a documented occupational, percutaneous exposure to HIV-infected blood by a needlestick or cut with a sharp object. HIV conversion had to be temporally related to the injury, and with no concurrent exposure. Control subjects were workers with documented occupational, percutaneous exposure to HIV-infected blood who were seronegative at least six months after exposure.

Results

There were 33 case patients and 679 controls from the USA, France, UK and Italy. Thirty of the 33 injuries were needlesticks with hollow bore needles. A similar proportion (91%) of injuries to controls were needlesticks, again mostly with hollow bore needles.

Using logistic-regression analysis, the 95% confidence intervals for odds ratio for the odds of seroconversion after exposure in workers with the risk factor compared with those without it are shown in Figure 1. Seroconversion was more likely to accompany deep injury (OR = 15), visible blood on the device (OR = 6), Procedure involving needle in artery or vein (OR = 4), death of source patient with AIDS within two month (OR = 6). Patients who seroconverted were less likely to have used zidovudine after exposure (OR = 0.2).

Figure 1: 95% confidence interval of odds ratio of risk factors for seroconversion


The absolute percentages of case and control patients with risk factors is shown in Table 1.

Table 1: Absolute percent of patients with risk factors


Risk factor

Percent of cases

Percent of controls

Large gauge hollow bore needle

15

1

Deep injury

52

7

Visible blood

84

35

Needle in artery or vein

73

31

Emergency procedure

12

2

Use of gloves

78

78

AIDS in source patient

82

70

Terminal illness in source patient

48

16

Postexposure use of zidovudine

27

36

Comment

A helpful and well done case-control study with an interesting discussion.