Percentages, crude and adjusted ORs for demographic and behavioural risk factors associated with testing positive for chlamydia, by data source: men and women
| Data source | Natsal-2 | NCSP | ||||||
| Demographic and behavioural risk factors | % (95% CI) testing positive | Crude OR (95% CI) | Adjusted OR‡(95% CI) | Denominator* † | % (95% CI) testing positive | Crude OR (95% CI) | Adjusted OR‡ (95% CI) | Denominator† |
| Men | ||||||||
| All | 3.0% (1.4% to 6.6%) | – | – | 270, 342 | 9.8% (9.0% to 10.6%) | – | – | 5491 |
| Age group (y) | p=0.986 | p=0.744 | p=0.118 | p=0.175 | ||||
| 18–19 | 3.1% (0.7% to 11.9%) | 1 | 1 | 68, 79 | 9.1% (8.0% to 10.3%) | 1 | 1 | 2517 |
| 20–24 | 3.0% (1.2% to 7.6%) | 0.98 (0.17 to 5.69) | 1.36 (0.21 to 8.79) | 202, 263 | 10.4% (9.3% to 11.5%) | 1.15 (0.96 to 1.38) | 1.13 (0.95 to 1.35) | 2974 |
| Ethnic group | p=0.535 | p=0.056 | p=0.333 | p=0.123 | ||||
| White | 3.0% (1.3% to 6.9%) | 1 | 1 | 243, 310 | 9.7% (8.9% to 10.5%) | 1 | 1 | 4943 |
| Black | 0.0% | NA | NA | 11, 12 | 12.3% (9.0% to 16.6%) | 1.31 (0.91 to 1.89) | 1.47 (1.02 to 2.13) | 285 |
| Other minority groups | 5.8% (0.8% to 32.9%) | 2.03 (0.22 to 19.0) | 9.13 (0.94 to 88.6) | 16, 20 | 9.1% (6.2% to 13.3%) | 0.94 (0.61 to 1.44) | 1.00 (0.65 to 1.55) | 263 |
| Condom use at last sex | p=0.033 | p=0.070 | p<0.001 | p<0.001 | ||||
| Yes | 0.5% (<0.01% to 3.5%) | 1 | 1 | 125, 151 | 7.5% (6.3% to 8.9%) | 1 | 1 | 1617 |
| No | 5.0% (2.2%–11.3%) | 10.4 (1.21 to 89.3) | 10.3 (0.82 to 127.8) | 145, 191 | 10.7% (9.8% to 11.8%) | 1.49 (1.20 to 1.84) | 1.53 (1.23 to 1.89) | 3874 |
| ≥2 sexual partners in last year | p<0.001 | p<0.001 | ||||||
| No | 0.0% | NA | NA | 140, 187 | 7.8% (6.8% to 8.9%) | 1 | 1 | 2491 |
| Yes | 6.7% (3.0% to 14.1%) | 130, 155 | 11.4% (10.3% to 12.6%) | 1.53 (1.27 to 1.84) | 1.62 (1.34 to 1.96) | 3000 | ||
| Women | ||||||||
| All | 2.8% (1.6% to 4.9%) | 357, 337 | 9.0% (8.5% to 9.5%) | 11768 | ||||
| Age group (y) | p=0.967 | p=0.809 | p=0.001 | p=0.010 | ||||
| 18–19 | 2.9% (0.9% to 8.8%) | 1 | 1 | 87, 85 | 10.0% (9.2% to 10.9%) | 1 | 1 | 4773 |
| 20–24 | 2.8% (1.5% to 5.3%) | 0.97 (0.25 to 3.74) | 1.18 (0.30 to 4.73) | 270, 252 | 8.2% (7.6% to 8.9%) | 0.80 (0.71 to 0.91) | 0.84 (0.74 to 0.96) | 6995 |
| Ethnic group | p=0.147 | p=0.145 | p=0.011 | p=0.030 | ||||
| White | 2.5% (1.3% to 4.5%) | 1 | 1 | 323, 309 | 9.1% (8.6% to 9.7%) | 1 | 1 | 11129 |
| Black | 13.7% (2.6% to 48.5%) | 6.31 (0.95 to 41.8) | 5.85 (0.96 to 35.8) | 11, 7 | 3.0% (1.3% to 6.4%) | 0.30 (0.13 to 0.69) | 0.34 (0.15 to 0.76) | 203 |
| Other minority groups | 5.1% (1.1% to 20.6%) | 2.12 (0.38 to 11.7) | 2.01 (0.37 to 10.9) | 23, 21 | 7.8% (5.6% to 10.7%) | 0.84 (0.59 to 1.21) | 0.91 (0.64 to 1.31) | 436 |
| Condom use at last sex | p=0.759 | p=0.034 | p=0.016 | p=0.004 | ||||
| Yes | 2.5% (1.0% to 6.1%) | 1 | 1 | 110, 97 | 8.0% (7.2% to 8.9%) | 1 | 1 | 3636 |
| No | 3.0% (1.5% to 5.8%) | 1.20 (0.37 to 3.86) | 1.31 (0.43 to 3.93) | 247, 240 | 9.4% (8.8% to 10.0%) | 1.19 (1.03 to 1.37) | 1.23 (1.07 to 1.42) | 8132 |
| ≥2 sexual partners in last year | p=0.068 | p=0.079 | p<0.001 | p<0.001 | ||||
| No | 1.9% (0.8% to 4.6%) | 1 | 1 | 244, 241 | 6.6% (6.0% to 7.2%) | 1 | 1 | 6070 |
| Yes | 5.3% (2.7% to 10.1%) | 2.92 (0.92 to 9.22) | 2.85 (0.88 to 9.22) | 113, 96 | 11.5% (10.7% to 12.3%) | 1.83 (1.61 to 2.09) | 1.81 (1.58 to 2.06) | 5698 |
↵* Unweighted, weighted denominators. Percentages and ORs are based on weighted data for Natsal-2.
↵† Denominator corresponds only to respondents with data available for all factors shown in table 2.
↵‡ Adjusted for all other factors in table 2.
NA, not applicable; NCSP, National Chlamydia Screening Programme.