TABLE 3—
Bivariate and Multivariate Analysis of Number of Sex Partners Among Interviewed Men Who Have Sex With Men (MSM) Diagnosed With Primary or Secondary Syphilis, by Methamphetamine and Internet Use: California, 2004–2008
| Sex Partner Statisticsa |
|||||||||
| Model | Total No. | Meth Use, No. (%) | No. of Cases | No. of Sex Partners, Mean (95% CI) | Median | 75th Percentile | 95th Percentile | Bivariate Pb | Multivariate P |
| Overall | 5916 | 1138 (19.2) | 5596 | 6.8 (6.4, 7.2) | 3.0 | 6.0 | 25.0 | ||
| Model 1c | |||||||||
| Nonmeth users | 4778 | … | 4491 | 5.6 (5.3, 5.9) | 3.0 | 5.0 | 20.0 | < .001 | < .001 |
| Meth users | 1138 | 1138 (100.0) | 1105 | 11.7 (10.4, 13.0) | 5.0 | 10.0 | 50.0 | ||
| No Internet use | 3768 | 538 (14.3) | 3508 | 5.0 (4.6, 5.4) | 2.0 | 4.0 | 19.0 | < .001 | < .001 |
| Internet use | 2148 | 600 (27.9) | 2088 | 9.8 (9.1, 10.5) | 5.0 | 10.0 | 36.0 | ||
| Model 2d (Internet users only) | < .001 | .04 | |||||||
| Single site | 1082 | 280 (25.9) | 1056 | 8.2 (7.4, 9.1) | 4.0 | 8.0 | 30.0 | ||
| Multiple sites | 564 | 199 (35.3) | 554 | 14.1 (12.3, 15.8) | 7.0 | 15.0 | 50.0 | ||
| Other sites | 228 | 56 (24.5) | 222 | 9.1 (6.7, 11.5) | 4.0 | 8.0 | 40.0 | ||
| Unknown | 274 | 65 (23.7) | 256 | 7.8 (6.3, 9.3) | 4.0 | 8.0 | 24.0 | ||
| Single-site users | |||||||||
| Model 3e (single-site users only) | < .001 | < .001 | |||||||
| Adam4Adam | 424 | 124 (29.3) | 416 | 7.2 (6.1, 8.4) | 3.5 | 7.0 | 25.0 | ||
| Manhunt | 274 | 98 (35.8) | 266 | 12.0 (9.5, 14.4) | 5.0 | 10.0 | 50.0 | ||
| Craigslist | 168 | 25 (14.9) | 162 | 7.0 (5.4, 8.7) | 4.0 | 7.0 | 20.0 | ||
| Gay.com | 172 | 22 (12.8) | 171 | 5.6 (4.2, 7.0) | 3.0 | 6.0 | 16.0 | ||
| AOL.com | 44 | 11 (25.0) | 41 | 9.9 (4.1, 15.6) | 4.0 | 8.0 | 50.0 | ||
Note. CI = confidence interval; meth = methamphetamine.
Sex partner statistics exclude cases with missing sex partner data.
P values for bivariate analysis were determined by the t test and 1-way analysis of variance.
For model 1, results for only Internet use and meth use are displayed. Bivariate analysis included (1) meth use, (2) Internet use, and (3) region (P < .001). For multivariate analysis, additional variables retained in the final model were region (P < .001), Internet use and meth use interaction (P = .01), and meth use and region interaction (P < .001).
For model 2, results for only Internet user groups are displayed. Bivariate analysis included (1) meth use (P < .001), (2) Internet user groups, and (3) region (P < .001). For multivariate analysis, additional variables retained in the final model were meth use (P < .001), region (P < .001), Internet user group and region interaction (P = .002), and meth use and region interaction (P = .02). Model 2 excluded Northern and Central regions.
For model 3, results for only single main sites are displayed. Bivariate analysis included (1) meth use (P < .001), (2) single main sites, and (3) region (P = .059). For multivariate analysis, additional variables retained in the final model were single main sites and meth use interaction (P = .03), meth use and region interaction (P = .096), and nonsignificant-terms meth use (P = .26) and region (P = .18).