Table 4.
Cluster growth rates in subsequent three-month period by cluster attribute, Washington State 2016–2017.
| Variable | Value | Cluster-Months | Absolute 3 Month Cluster Growth, Mean (5% CI) a | p-Value | Cluster Growth Per 100 Person-Months, Mean (95% CI) a | p-Value |
|---|---|---|---|---|---|---|
| Total Population | All | 2318 | 0.24 (0.18–0.33) | 1.22 (0.86–1.73) | ||
| Viremic Individuals | 0 | 344 | 0.13 (0.08–0.20) | 0.023 | 1.20 (0.72–2.01) | 0.212 |
| 1 | 533 | 0.22 (0.15–0.33) | 1.69 (1.04–2.76) | |||
| 2 | 462 | 0.18 (0.12–0.27) | 1.00 (0.65–1.55) | |||
| 3+ | 530 | 0.38 (0.26–0.57) | 0.96 (0.55–1.68) | |||
| Percent Viremic (Quartiles) | <12% | 353 | 0.12 (0.08–0.20) | 0.024 | 1.17(0.70–1.96) | 0.248 |
| 12–25% | 692 | 0.32 (0.23–0.46) | 0.92 (0.63–1.35) | |||
| 26–35% | 496 | 0.23 (0.15–0.35) | 1.19 (0.76–1.88) | |||
| ≥35% | 328 | 0.21 (0.13–0.36) | 1.97 (1.05–3.69) | |||
| Cluster Size (Quartiles) | ≤3 | 517 | 0.17 (0.11–0.27) | 0.010 | 2.07 (1.29–3.34) | 0.011 |
| 4–5 | 430 | 0.13 (0.08–0.20) | 0.93 (0.60–1.45) | |||
| 6–12 | 498 | 0.30 (0.19–0.47) | 1.26 (0.80–2.00) | |||
| >12 | 424 | 0.37 (0.24–0.58) | 0.43 (0.33–0.58) | |||
| % White | <16% | 939 | 0.23 (0.15–0.35) | 0.685 | 1.18 (0.71–1.95) | 0.774 |
| ≥18% | 930 | 0.25 (0.18–0.35) | 1.27 (0.88–1.85) | |||
| % Female | 0% | 1343 | 0.21 (0.15–0.31) | 0.203 | 1.18 (0.76–1.82) | 0.727 |
| >0% | 526 | 0.31 (0.21–0.47) | 1.34 (0.76–2.35) | |||
| % IDU | <16% | 943 | 0.24 (0.17–0.35) | 0.966 | 0.93 (0.70–1.23) | 0.165 |
| ≥15% | 926 | 0.24 (0.15–0.38) | 1.52 (0.90–2.58) | |||
| % Late | <13% | 932 | 0.24 (0.16–0.35) | 0.933 | 1.08 (0.73–1.62) | 0.522 |
| ≥13% | 937 | 0.24 (0.16–0.38) | 1.36 (0.80–2.33) | |||
| % Diagnosed in Past 5 Years | <25% | 363 | 0.19 (0.13–0.29) | 0.721 | 1.05 (0.56–1.98) | 0.572 |
| 25–50% | 702 | 0.26 (0.17–0.40) | 1.09 (0.67–1.79) | |||
| 51–66% | 349 | 0.26 (0.17–0.38) | 1.45 (0.95–2.21) | |||
| >66% | 455 | 0.24 (0.13–0.46) | 1.39 (0.85–2.25) | |||
| 3 Cases in Previous 12 Months (0.015) | No | 1685 | 0.18 (0.15–0.22) | 0.022 | 1.09 (0.83–1.41) | 0.253 |
| Yes | 184 | 0.78 (0.47–1.27) | 2.49 (0.98–6.33) | |||
| 5 Cases in Previous 12 Months (0.015) | No | 1819 | 0.21 (0.17–0.27) | 0.088 | 1.16 (0.86–1.56) | 0.263 |
| Yes | 50 | 1.26 (0.89–1.78) | 3.69 (1.49–9.14) | |||
| 3 Cases in Previous 12 Months (0.005) | No | 1818 | 0.21 (0.17–0.27) | 0.058 | 1.17 (0.85–1.62) | 0.224 |
| Yes | 51 | 1.29 (0.74–2.26) | 3.00 (1.19–7.58) | |||
| 5 Cases in Previous 12 Months (0.005) | No | 1847 | 0.23 (0.17–0.29) | 0.116 | 1.20 (0.86–1.68) | 0.388 |
| Yes | 22 | 1.50 (0.79–2.86) | 2.93 (0.79–10.86) |
IDU = Injection Drug Use Transmission Risk. a Calculated from number of newly diagnosed cases joining the cluster in the subsequent three-month period. Estimates, 95% confidence intervals, and p-values from repeated-measures generalized estimating equation using a Poisson distribution.