Table 2.
HIV incidence per 100 person-years by sex and demographic and behavioral characteristics—household cohort study of adults aged ≥15 years in the Zambezi region of Namibia, 2014 to 2016 (N=1624).
| Variable | Women | Men | |||||
|
|
Incident infections | Rate per 100 person, years (CI)a | P value | Incident infections | Rate per 100 person, years (CI) | P value | |
| Overall | 17 | 1.55 (1.12-2.17) | .29 | 9 | 1.05 (0.54-2.31) | Refb | |
| Age (years)c | |||||||
|
|
15-19 | 5 | 2.42 (0.97-7.34) | .42 | 0 | 0.00 (0.00-2.44) | —d |
|
|
20-24 | 5 | 1.88 (1.05-3.57) | .68 | 1 | 0.53 (0.01-2.93) | Ref |
|
|
25-29 | 2 | 1.23 (0.31-8.52) | Ref | 1 | 0.69 (0.02-3.87) | .80 |
|
|
30-34 | 4 | 3.09 (1.68-6.61) | .40 | 2 | 1.86 (0.50-12.51) | .25 |
|
|
35-39 | 0 | 0.00 (0.00-4.53) | — | 1 | 1.00 (0.03-5.57) | .60 |
|
|
40-44 | 0 | 0.00 (0.00-6.25) | — | 4 | 8.21 (3.76-21.14) | <.001 |
|
|
45-49 | 1 | 2.89 (0.07-16.10) | .61 | 0 | 0.00 (0.00-9.23) | — |
|
|
50-64 | 0 | 0.00 (0.00-2.34) | — | 0 | 0.00 (0.00-4.95) | — |
| Currently marriedc | |||||||
|
|
No | 14 | 2.20 (1.38-3.49) | .03 | 6 | 1.12 (0.49-2.87) | .79 |
|
|
Yes | 3 | 0.65 (0.25-2.21) | Ref | 3 | 0.94 (0.38-3.08) | Ref |
| Sitec | |||||||
|
|
Ngweze urban | 5 | 1.88 (1.23-3.02) | <.001 | 1 | 0.58 (0.01-3.21) | Ref |
|
|
Mavuluma urban | 3 | 1.17 (0.41-3.86) | Ref | 2 | 1.29 (0.16-4.64) | .75 |
|
|
Bukalo rural | 3 | 1.47 (0.41-5.40) | .36 | 3 | 1.31 (0.27-3.84) | .58 |
|
|
Ngoma rural | 2 | 1.59 (1.46-1.76) | .005 | 2 | 1.61 (1.34-1.96) | .34 |
|
|
Sibbinda rural | 4 | 1.81 (0.75-5.83) | .11 | 1 | 0.70 (0.02-3.89) | .94 |
| Residencec | |||||||
|
|
Rural | 9 | 1.62 (0.99-2.76) | .53 | 6 | 1.20 (0.51-3.60) | .54 |
|
|
Urban | 8 | 1.47 (0.91-2.48) | Ref | 3 | 0.85 (0.23-5.36) | Ref |
| Age (years) and residencec | |||||||
|
|
15-24 and rural | 7 | 3.59 (1.60-8.69) | .04 | 0 | 0.00 (0.00-1.94) | — |
|
|
15-24 and urban | 3 | 1.08 (0.66-1.93) | .58 | 1 | 0.65 (0.02-3.64) | Ref |
|
|
≥25 and rural | 2 | 0.56 (0.14-3.59) | Ref | 6 | 1.93 (0.94-5.01) | .08 |
|
|
≥25 and urban | 5 | 1.88 (0.83-4.92) | .18 | 2 | 0.99 (0.31-4.48) | .36 |
| Tested for HIV in the 12 months before enrollmentc | |||||||
|
|
No | 14 | 1.97 (1.32-2.95) | .05 | 5 | 0.77 (0.32-2.31) | .11 |
|
|
Yes | 3 | 0.78 (0.33-2.41) | Ref | 4 | 1.95 (1.03-4.24) | Ref |
| Tested with a partner at enrollmentc | |||||||
|
|
No | 16 | 2.05 (1.41-2.98) | .05 | 7 | 1.15 (0.54-2.75) | .57 |
|
|
Yes | 1 | 0.30 (0.01-1.69) | Ref | 2 | 0.82 (0.22-5.47) | Ref |
| Had a serodiscordant positive partner (among those tested with a partner)c | |||||||
|
|
No | 0 | 0.00 (0.00-1.18) | — | 1 | 0.47 (0.01-2.63) | Ref |
|
|
Yes | 1 | 6.82 (0.17-38.01) | Ref | 1 | 3.06 (0.08-17.03) | .23 |
| Partner on antiretroviral therapy (among those with serodiscordant positive partner)c | |||||||
|
|
No | 1 | 9.94 (0.25-55.38) | Ref | 1 | 4.07 (0.10-22.68) | Ref |
|
|
Yes | 0 | 0.00 (0.00-80.02) | — | 0 | 0.00 (0.00-45.26) | — |
| Circumcised (among men only)c | |||||||
|
|
No | N/Ae | N/A | — | 9 | 1.13 (0.58-2.49) | Ref |
|
|
Yes | N/A | N/A | — | 0 | 0.00 (0.00-9.78) | — |
| Sought testing for HIV outside the study in past 12 monthsf | |||||||
|
|
No | 11 | 1.17 (0.68-2.12) | .14 | 4 | 0.53 (0.17-2.42) | .03 |
|
|
Yes | 6 | 3.72 (1.64-9.27) | Ref | 5 | 5.23 (1.99-16.65) | Ref |
| Had a sex partner residing outside of study area in past 12 monthsf | |||||||
|
|
No | 13 | 1.82 (1.31-2.57) | .13 | 4 | 0.67 (0.30-1.73) | .05 |
|
|
Yes | 3 | 2.98 (1.62-6.71) | Ref | 2 | 2.79 (0.34-10.07) | Ref |
| Engaged in transactional sex in the past 12 monthsf | |||||||
|
|
No | 15 | 1.38 (0.88-2.24) | .01 | 9 | 1.11 (0.55-2.51) | Ref |
|
|
Yes | 2 | 22.75 (3.79-100) | Ref | 0 | 0.00 (0.00-8.52) | — |
| Used a condom at the last sexual encounterc | |||||||
|
|
No | 9 | 2.52 (1.15-5.08) | .37 | 1 | 0.32 (0.08-1.76) | .23 |
|
|
Yes | 7 | 1.53 (0.84-3.03) | Ref | 5 | 1.41 (0.45-7.42) | Ref |
| Used condoms consistently with all sex partners in the past 12 monthsf | |||||||
|
|
No | 14 | 1.88 (1.45-2.48) | .98 | 7 | 1.21 (0.62-2.72) | .64 |
|
|
Yes | 2 | 2.82 (0.67-20.52) | Ref | 1 | 0.87 (0.02-4.60) | Ref |
| Had multiple sex partners in the past 12 monthsf | |||||||
|
|
No | 15 | 1.38 (0.89-2.25) | .02 | 9 | 1.09 (0.56-2.41) | Ref |
|
|
Yes | 2 | 14.78 (3.81-94.41) | Ref | 0 | 0.00 (0.00-12.07) | — |
aCIs are cluster-robust unless there are 1 or 0 seroconversions, in which case the CI is Poisson exact. CI is 2-sided 95% except when there are 0 seroconversions, in which cases CI is 1-sided 97.5%.
bRef is the reference group for Cox models.
cData collected at baseline.
dP values were not calculated when there were 0 seroconversions.
eN/A: not applicable.
fData collected at follow-up.