Table 5.
Cluster growth rates in subsequent 12-month period by cluster attribute, Washington State 2016–2017.
| Variable | Value | Cluster-Months | Absolute 12-Month Cluster Growth, Mean (95% CI) a | p-value | Cluster Growth Per 100 Person-Months, Mean (95% CI) a | p-Value |
|---|---|---|---|---|---|---|
| Total Population | All | 2318 | 1.02 (0.75–1.38) | 1.27 (0.89–1.81) | ||
| Viremic Individuals | 0 | 344 | 0.62 (0.31–1.25) | 0.081 | 1.35 (0.60–3.05) | 0.369 |
| 1 | 533 | 0.85 (0.59–1.23) | 1.61 (1.07–2.42) | |||
| 2 | 462 | 0.82 (0.57–1.20) | 1.18 (0.78–1.81) | |||
| 3+ | 530 | 1.62 (1.09–2.41) | 0.95 (0.56–1.62) | |||
| Percent Viremic (Quartiles) | <12% | 353 | 0.65 (0.34–1.25) | 0.216 | 1.33 (0.59–2.98) | 0.056 |
| 12%–25% | 692 | 1.28 (0.87–1.87) | 0.83 (0.56–1.22) | |||
| 26%–35% | 496 | 0.95 (0.65–1.39) | 1.40 (0.95–2.07) | |||
| ≥35% | 328 | 0.98 (0.55–1.77) | 1.94 (1.06–3.53) | |||
| Cluster Size (Quartiles) | ≤3 | 517 | 0.74 (0.48–1.17) | 0.029 | 2.14 (1.37–3.34) | 0.014 |
| 4–5 | 430 | 0.53 (0.33–0.84) | 0.94 (0.60–1.49) | |||
| 6–12 | 498 | 1.28 (0.79–2.09) | 1.37 (0.81–2.32) | |||
| >12 | 424 | 1.55 (0.96–2.50) | 0.42 (0.32–0.55) | |||
| % White | <16% | 939 | 0.87 (0.58–1.20) | 0.237 | 1.15 (0.71–1.84] | 0.521 |
| ≥18% | 930 | 1.18 (0.80–1.72) | 1.40 (0.89–2.20) | |||
| % Female | 0% | 1343 | 0.83 (0.57–1.22) | 0.072 | 1.04 (0.69–1.55) | 0.184 |
| >0% | 526 | 1.50 (0.98–2.30) | 1.87 (1.02–3.41) | |||
| % IDU | <16% | 943 | 0.99 (0.66–1.48) | 0.836 | 0.84 (0.63–1.11) | 0.050 |
| ≥15% | 926 | 1.05 (0.68–1.62) | 1.71 (1.05–2.78) | |||
| % Late | <13% | 932 | 1.03 (0.68–1.57) | 0.940 | 1.11 (0.66–1.86) | 0.472 |
| ≥13% | 937 | 1.01 (0.66–1.55) | 1.43 (0.89–2.31) | |||
| % Diagnosed in Past 5 Years | <25% | 363 | 0.87 (0.54–1.39) | 0.670 | 1.28 (0.55–2.97) | 0.143 |
| 25–50% | 702 | 1.02 (0.63–1.65) | 0.94 (0.61–1.45) | |||
| 51–66% | 349 | 1.27 (0.83–1.96) | 1.96 (1.22–3.15) | |||
| >66% | 455 | 0.95 (0.49–1.87) | 1.24 (0.70–2.19) | |||
| 3 Cases in Previous 12 Months (0.015) | No | 1685 | 0.82 (0.64–1.05) | 0.029 | 1.15 (0.85–1.58) | 0.252 |
| Yes | 184 | 2.88 (1.77–4.69) | 2.33 (1.01–5.42) | |||
| 5 Cases in Previous 12 Months (0.015) | No | 1819 | 0.91 (0.7–1.19) | 0.105 | 1.20 (0.86–1.67) | 0.337 |
| Yes | 50 | 4.98 [3.28–7.55) | 3.75 (1.32–10.67) | |||
| 3 Cases in Previous 12 Months (0.005) | No | 1818 | 0.91 (0.7–1.18) | 0.041 | 1.20 (0.86–1.68) | 0.154 |
| Yes | 51 | 5.12 [3.4–7.69) | 3.74 (1.75–8.00) | |||
| 5 Cases in Previous 12 Months (0.005) | No | 1847 | 0.97 (0.73–1.29) | 0.098 | 1.26 (0.89–1.79) | 0.507 |
| Yes | 22 | 4.91 (2.7–8.92) | 2.11 (0.62–7.19) |
IDU = Injection Drug Use Transmission Risk.a Calculated from number of newly diagnosed cases joining the cluster in the subsequent 12-month period. Estimates, 95% confidence intervals, and p-values from repeated-measures generalized estimating equation using a Poisson distribution.