Table 3.
Chlamydia test positivity and estimated population prevalence, by region, sex and screening invitation
| No of people who participated | No (%) positive for chlamydia | Change in positivity from 1st invite (%) | Change in positivity compared with control block | Estimated prevalence (% (95% CI))* | ||
|---|---|---|---|---|---|---|
| Change (%) | Odd ratio (95% CI); P value | |||||
| Total: | 102 283 | 4252 (4.2) | 2.7 | |||
| 1st invitation | 43 358 | 1851 (4.3) | — | −0.02 | 1.00 (0.87 to 1.13); 0.94 | 2.6 |
| 2nd invitation | 28 803 | 1153 (4.0) | −0.3 | −0.29 | 0.93 (0.81 to 1.07); 0.30 | 2.6 |
| 3rd invitation | 23 899 | 981 (4.1) | −0.2 | −0.19 | 0.96 (0.83 to 1.10); 0.52 | 2.6 |
| Control | 6223 | 267 (4.3) | — | — | 1.00 (reference) | 3.0 |
| Region | ||||||
| Amsterdam: | ||||||
| 1st invitation | 24 059 | 871 (3.6) | — | 0.24 | 1.07 (0.87 to 1.33); 0.51 | 2.6 (2.4 to 2.8) |
| 2nd invitation | 16 355 | 565 (3.5) | −0.2 | 0.07 | 1.02 (0.82 to 1.27); 0.84 | 2.5 (2.3 to 2.7) |
| 3rd invitation | 13 866 | 476 (3.4) | −0.2 | 0.05 | 1.01 (0.81 to 1.26); 0.92 | 2.5 (2.2 to 2.7) |
| Control | 2899 | 98 (3.4) | — | — | 1.00 (reference) | 3.0 (2.1 to 3.9) |
| Rotterdam: | ||||||
| 1st invitation | 16 414 | 834 (5.1) | — | −0.46 | 1.06 (0.95 to 1.19); 0.30 | 3.7 (3.4 to 3.9) |
| 2nd invitation | 10 753 | 519 (4.8) | −0.3 | −0.72 | 0.91 (0.75 to 1.11); 0.36 | 3.5 (3.2 to 3.8) |
| 3rd invitation | 9057 | 478 (5.3) | 0.2 | −0.27 | 0.95 (0.77 to 1.16); 0.60 | 3.9 (3.6 to 4.3) |
| Control | 2254 | 125 (5.5) | — | — | 1.00 (reference) | 3.9 (3.2 to 4.6) |
| South Limburg: | ||||||
| 1st invitation | 2885 | 146 (5.1) | — | 0.95 | 1.24 (0.88 to 1.75); 0.22 | 3.2 (2.7–3.6)† |
| 2nd invitation | 1687 | 69 (4.1) | −1.0 | −0.02 | 0.99 (0.67 to 1.46); 0.96 | 2.6 (2.4–2.8)† |
| 3rd invitation | 874 | 27 (3.1) | −2.0 | −1.02 | 0.74 (0.45 to 1.21); 0.23 | 1.8 (1.7–1.9)† |
| Control | 1070 | 44 (4.1) | — | — | 1.00 (reference) | 2.5 (2.3–2.6)† |
| Gender | ||||||
| Male: | ||||||
| 1st invitation | 13 617 | 522 (3.8) | — | −0.22 | 0.94 (0.74 to 1.20); 0.64 | 3.5 |
| 2nd invitation | 8616 | 318 (3.7) | −0.1 | −0.36 | 0.91 (0.71 to 1.16); 0.45 | 3.3 |
| 3rd invitation | 6970 | 283 (4.1) | 0.2 | 0.01 | 1.00 (0.78 to 1.29); 0.98 | 3.6 |
| Control | 2025 | 82 (4.0) | — | — | 1.00 (reference) | 3.8 |
| Female: | ||||||
| 1st invitation | 29 831 | 1329 (4.5) | — | 0.05 | 1.02 (0.87 to 1.19); 0.85 | 3.1 |
| 2nd invitation | 20 246 | 835 (4.1) | −0.3 | −0.28 | 0.94 (0.80 to 1.10); 0.43 | 2.7 |
| 3rd invitation | 16 853 | 698 (4.1) | −0.3 | −0.26 | 0.93 (0.79 to 1.10); 0.42 | 2.9 |
| Control | 4199 | 185 (4.4) | — | — | 1.00 (reference) | 3.1 |
*Confidence intervals are not corrected for cluster effect (inter-cluster effect on positivity was not significant). Confidence intervals could not be calculated for South Limburg, so they are also unavailable for the total population and estimates by gender.
†Values are intermediates with high and low estimates rather than confidence intervals.