Estimated Incidence Bone Donors
Number Number of Incidence per 100,000 Incidence per 100,000 Seroconverted person-years person-years (95% CI) person-years (95% CI) 1993-1995 5 1,276,407 1.89 (0.70 - 4.70) 20.76 (7.67 - 51.23) 1996-1998 4 1,326,310 1.46 (0.47 - 4.01) 20.65 (6.66 - 56.80) 1999-2001 2 1,402,765 0.69 (0.12 - 2.78) 10.83 (1.89 - 43.69) 2002-2004 1 1,611,496 0.30 (0.02 - 1.95) 3.94 (0.26 - 25.57)
HIV First-Time Blood Donors
HIV Incidence Trends
0 5 10 15 20 25
1993-1995 1996-1998 1999-2001 2002-2004
Incidence per 100,000 person-years
Blood Donors Bone Donors
* p = 0.216
* p < 0.0001
Estimated Incidence Bone Donors
Number Number of Incidence per 100,000 Incidence per 100,000 Seroconverted person-years person-years (95% CI) person-years (95% CI) 1993-1995 1 1,178,614 0.77 (0.04 - 5.01) 2.87 (0.15 - 18.66) 1996-1998 3 1,326,310 2.06 (0.53 - 6.55) 6.05 (1.56 - 19.29) 1999-2001 4 1,402,765 2.59 (0.83 - 7.13) 9.77 (3.13 - 26.89) 2002-2004 2 1,611,496 1.13 (0.20 - 4.55) 3.06 (0.54 - 12.34)
First-Time Blood Donors HBV
HBV Incidence Trends
0 2 4 6 8 10 12
1993-1995 1996-1998 1999-2001 2002-2004
Incidence per 100,000 person-years
Blood Donors Bone Donors
* p = 0.630
* p = 0.016
FIGURE 2. Trends of the estimated incidence of transfusion-transmissible viral infections per 100,000 person-years among musculoskeletal tissue donors and first-time blood donors by period of time. Estimated incidence rates and exact 95% confidence intervals were calculated for each viral marker for four 3-year independent periods (1993–1995, 1996 – 1998, 1999 –2001, and 2002–2004). Incidence estimates were calculated by extrapolating from rates obtained in first-time blood donors using a previously published method (1) as follows: Incidence in first time blood donors⫽(number of sero- converters⫻100,000⫻2.03)/(number of repeat donors⫻0.42) where, 2.03 is the correction factor to derive first-time blood donor incidence from repeat donor incidence rates and 0.42 is the number of person-years of observation derived by the standard incidence method in a published study of Australian blood donors (8). The incidence for HBV was multiplied by an ARCBS adjustment factor of 1.88 to compensate for the potential underestimation of HBV incidence because of the
Estimated Incidence Bone Donors
Number Number of Incidence per 100,000 Incidence per 100,000 Seroconverted person-years person-years (95% CI) person-years (95% CI) 1993-1995 18 1,276,407 6.82 (4.17 - 11.01) 10.85 (6.64 - 17.53)
1996-1998 12 1,326,310 4.37 (2.37 - 7.88) 10.43 (5.65 - 18.80)
1999-2001 9 1,402,765 3.10 (1.51 - 6.12) 9.39 (4.57 - 18.53)
2002-2004 8 1,611,496 2.40 (1.12 - 4.93) 12.29 (5.74 - 25.25)
HCV First -Time Blood Donors
HCV Incidence Trends
0 2 4 6 8 10 12 14
1993-1995 1996-1998 1999-2001 2002-2004
Incidence per 100,000 person-years
Blood Donors Bone Donors
* p = 0.047
* p = 0.727
FIGURE 2. (Continued) transient nature of HBsAg. Estimated incidence in tissue donors⫽([prevalence in tissue donors]/
[prevalence in first-time blood donors])⫻incidence in first-time blood donors. The small number in incident cases among first-time blood donors prevented us from evaluating trends in HTLV incidence. The 95% confidence interval for rates were obtained by the Fleiss Quadratic method, which is adapted when proportions are close to zero (2). *Assessment of signif- icance for linear trend was performed by the Fisher’s exact test or Pearson chi-square test as appropriate. APvalue of less than 0.05 indicates that a trend is significant.
TABLE 1. Estimated residual risk of transfusion-transmitted viral infections among musculoskeletal tissue donors in Australia, 1993–2004
Viral infections
Window period (d) (95% CI)
Estimated incidence rate bone donors/100,000
person-yr
Residual risk (95% CI)
Estimated probability of infection/
100,000 donors (95% CI) HIV
1993–1995 22 (6–38) (4) 20.76 1.25 (0.34–2.16) 1 in 80,000 (1/294,000–1/46,000)
1996–1998 20.65 1.24 (0.34–2.15) 1 in 81,000 (1/294,000–1/47,000)
1999–2001 10.83 0.65 (0.18–1.13) 1 in 154,000 (1/556,000–1/88,000)
2002–2004 3.94 0.24 (0.06–0.41) 1 in 417,000 (1/1,667,000–1/244,000)
HBV
1993–1995 43.6 (37.4–49.7) (5) 2.87 0.34 (0.29–0.39) 1 in 2,92,000 (1/345,000–1/256,000)
1996–1998 6.05 0.72 (0.62–0.82) 1 in 138,000 (1/161,000–1 in 122,000)
1999–2001 9.77 1.17 (1.00–1.33) 1 in 86,000 (1/100,000–1/75,000)
2002–2004 3.06 0.37 (0.31–0.42) 1 in 274,000 (1/323,000–1/238,000)
HCV
1993–1995 66 (38–94) (6,7) 10.85 1.96 (1.13–2.79) 1 in 51,000 (1/88,000–1/36,000)
1996–1998 10.43 1.89 (1.09–2.87) 1 in 53,000 (1/92,000–1/35,000)
1999–2001 9.39 1.70 (0.98–2.42) 1 in 59,000 (1/102,000–1/41,000)
2002–2004 12.29 2.22 (1.28–3.16) 1 in 45,000 (1/78,000–1/32,000)
The residual risk was calculated using the Modified Incidence-Window Period Model. Estimated probability of viremia⫽(window period/365 d)⫻incidence rate. Confidence intervals (CIs) for individual risk estimates were derived by direct calculation of the risk with the upper and lower CI for the window period.
