Table 1. Mean log-transformed number of chlamydia copies per millilitre (Ct/ml) (anorectal load) and associated determinants in MSM, women who reported anal sex and women who did not report anal sex by univariate linear regression analyses.
| MSM who reported anal sex N = 90 | Women who reported anal sex N = 51 | Women who did not report anal sex N = 61 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| % (N) | Mean log load (SD) | Δ load‡ | 95% CI | % (N) | Mean log load (SD) | Δ load‡ | 95% CI | % (N) | Mean log load (SD) | Δ load‡ | 95% CI | |
| Anorectal load | 3.5(1.4) | -0.33 | -0.85–0.19 | 3.8 (1.7) | ref | 2.8 (1.6) | -1.04* | -1.67–-0.41 | ||||
| Adjusted anorectal load | 0.29 | -0.34–0.92 | ref | -1.01* | -1.67–-0.035 | |||||||
| Age | ||||||||||||
| 16–21 | 11.1 (10) | 3.9 (1.1) | ref | 47.1 (24) | 4.1 (1.9) | ref | 52.2 (32) | 2.9 (1.5) | ref | |||
| 22–32 | 32.2 (29) | 3.4 (1.6) | -0.42 | -1.41–0.57 | 41.2 (21) | 3.6 (1.7) | -0.51 | -1.55–0.53 | 31.1 (19) | 2.6 (1.8) | -0.26 | -1.22–0.70 |
| 33+ | 56.7 (51) | 3.4 (1.2) | -0.43 | -1.37–0.50 | 11.8 (6) | 3.6 (1.1) | -0.44 | -2.03–1.14 | 16.4 (10) | 2.7 (1.9) | -0.18 | -1.38–1.03 |
| Nationality | ||||||||||||
| Western | 94.4 (84) | 3.5 (1.3) | ref | 98.0 (50) | 3.7 (1.7) | na | na | 95.0 (57) | 2.8 (1.6) | ref | ||
| Non Western | 5.6 (5) | 3.1 (1.4) | -0.32 | -1.55–0.92 | 2.9 (1) | 6.4 (-) | na | na | 5.0 (3) | 2.0 (1.3) | -0.88 | -2.82–1.06 |
| Number of sex partners | ||||||||||||
| 1–2 | 16.2 (14) | 3.6 (1.2) | ref | 53.1 (26) | 3.5 (1.6) | ref | 62.7 (37) | 2.8 (1.6) | ref | |||
| 3–5 | 35.6 (31) | 3.5 (1.4) | -0.04 | -0.91–0.84 | 30.6 (15) | 4.0 (1.8) | 0.53 | -0.53–1.59 | 23.7 (14) | 2.7 (1.8) | -0.14 | -1.19–0.91 |
| 6+ | 48.3 (42) | 3.3 (1.4) | -0.27 | -1.11–0.57 | 16.3 (8) | 4.6 (1.5) | 1.14 | -0.19–2.46 | 13.6 (8) | 2.7 (1.9) | -0.19 | -1.50–1.11 |
| Antibiotics | ||||||||||||
| No | 86.5 (77) | 3.4 (1.4) | ref | 86.3 (44) | 3.9 (1.7) | ref | 87.5 (49) | 2.9 (1.6) | ref | |||
| Yes | 6.7 (6) | 4.3 (0.7) | 0.43 | -0.10–0.95 | 13.7 (7) | 3.2 (1.5) | -0.74 | -2.14–0.66 | 12.5 (7) | 1.9 (1.2) | -0.07 | -0.74–0.89 |
| Urogenital symptoms | ||||||||||||
| No | 83.5 (71) | 3.5 (1.3) | ref | 72.5 (37) | 3.7 (1.8) | ref | 81.0 (47) | 2.8 (1.6) | ref | |||
| Yes | 16.5 (14) | 3.3 (1.6) | -0.20 | -0.99–0.59 | 27.5 (14) | 4.0 (1.6) | 0.22 | -0.87–1.31 | 19.0 (11) | 2.3 (1.5) | -0.50 | -1.59–0.59 |
| Anorectal symptoms | ||||||||||||
| No | 80.0 (68) | 3.4 (1.3) | ref | 84.3 (43) | 3.7 (1.7) | ref | 96.5 (55) | 2.6 (1.6) | ref | |||
| Yes | 20.0 (17) | 3.5 (1.4) | 0.04 | -0.70–0.77 | 15.7 (8) | 4.2 (1.7) | 0.47 | -0.87–1.80 | 3.5 (2) | 2.8 (0.6) | 0.19 | -2.13–2.52 |
| Concurrent urogenital chlamydia infection† | ||||||||||||
| No | 86.5 (77) | 3.4 (1.4) | ref | |||||||||
| Yes | 13.5 (12) | 4.0 (1.3) | 0.60 | -0.23–1.43 | ||||||||
| TPHA positive† | ||||||||||||
| Not tested | 65.6 (59) | 3.4 (1.3) | -0.41 | -0.99–0.16 | ||||||||
| No | 26.7 (24) | 3.7 (1.6) | ref | |||||||||
| Yes | 7.8 (7) | 3.5 (0.9) | -0.16 | -1.45–1.13 | ||||||||
| HIV positive† | ||||||||||||
| No | 72.2 (65) | 3.4 (1.5) | ref | |||||||||
| Yes | 26.7 (24) | 3.7 (1.0) | 0.37 | -0.27–1.02 | ||||||||
| Anorectal gonorrhoea† | ||||||||||||
| No | 84.4 (76) | 3.5 (1.4) | ref | |||||||||
| Yes | 15.6 (14) | 3.1 (1.2) | -0.47 | -1.25–0.31 | ||||||||
† Concurrent STIs were only assessed as a determinant for MSM since all the women had concurrent urogenital chlamydia and tested negative for TPHA and HIV; all but one woman were also negative for anorectal gonorrhoea.
‡ The regression coefficient is represented as Δ load, which represents the change in anorectal chlamydia load between the categories.
Sensitivity analyses were performed by excluding unquantifiable (0.75 log) load samples in analyses, but results remained the same.
Na = not assessed.
* P<0.05.