Table 2.
Determinants of Persistence of Oncogenic Non–Human Papillomavirus 16/18 Infections
| Characteristics | No. of Incident Infections | No. of Persistent Infections | % of Infections That Persist | Unadjusted RR (95% CI) |
Adjusted RRa (95% CI) |
|---|---|---|---|---|---|
| Age, y | |||||
| 18–21 | 265 | 63 | 23.8 | 0.74 (.55–.98) | 0.81 (.53–1.25) |
| 22–25 | 506 | 113 | 22.3 | 0.69 (.54–.88) | 0.81 (.57–1.15) |
| 26–29 | 433 | 118 | 27.3 | 0.84 (.67–1.07) | 0.97 (.74–1.26) |
| 30–37 | 251 | 81 | 32.3 | Reference | Reference |
| P value for trend | .009 | .28 | |||
| Sexual behavior | |||||
| AFI, y | |||||
| ≤15 | 284 | 75 | 26.4 | 1.03 (.81–1.30) | 1.12 (.85–1.47) |
| 16–17 | 390 | 99 | 25.4 | 0.99 (.80–1.22) | 0.99 (.79–1.25) |
| ≥18 | 781 | 201 | 25.7 | Reference | Reference |
| P value for trend | .88 | .49 | |||
| LNSP | |||||
| 1 | 374 | 95 | 25.4 | Reference | Reference |
| 2–3 | 597 | 154 | 25.8 | 1.02 (.81–1.28) | 1.00 (.79–1.27) |
| ≥4 | 484 | 126 | 26.0 | 1.02 (.81–1.30) | 0.96 (.73–1.26) |
| P value for trend | .84 | .76 | |||
| Monthly frequency of sexual intercourse since last visit | |||||
| ≤1 | 198 | 58 | 29.3 | 1.19 (.89–1.59) | 1.21 (.88–1.68) |
| 2–4 | 407 | 107 | 26.3 | 1.07 (.85–1.34) | 1.08 (.84–1.38) |
| 5–9 | 325 | 83 | 25.5 | 1.04 (.80–1.34) | 1.00 (.78–1.29) |
| ≥10 | 476 | 117 | 24.6 | Reference | Reference |
| P value for trend | .25 | .29 | |||
| Married/living as married | |||||
| Yes | 666 | 173 | 26.0 | Reference | Reference |
| No | 780 | 200 | 25.6 | 0.99 (.82–1.19) | 0.98 (.78–1.22) |
| Contraceptive use (among sexually active) | |||||
| Use of oral contraceptives | |||||
| Never | 263 | 70 | 26.6 | Reference | Reference |
| Ever | 1039 | 272 | 26.2 | 0.98 (.77–1.25) | 0.89 (.69–1.14) |
| Use of injectable contraceptives | |||||
| Never | 714 | 184 | 25.8 | Reference | Reference |
| Ever | 591 | 154 | 26.1 | 1.01 (.84–1.22) | 0.88 (.70–1.12) |
| Use of condoms | |||||
| Never | 320 | 83 | 25.9 | Reference | Reference |
| Ever | 839 | 220 | 26.2 | 1.01 (.81–1.26) | 1.01 (.79–1.29) |
| Use of other contraceptive methodb | |||||
| Never | 1241 | 327 | 26.4 | Reference | Reference |
| Ever | 193 | 44 | 22.8 | 0.87 (.65–1.15) | 0.78 (.57–1.06) |
| No. of full–term pregnancies | |||||
| 0 | 579 | 138 | 23.8 | Reference | Reference |
| 1–2 | 723 | 188 | 26.0 | 1.09 (.89–1.33) | 1.05 (.83–1.33) |
| ≥3 | 153 | 49 | 32.0 | 1.34 (1.02–1.78) | 1.07 (.75–1.53) |
| P value for trend | .059 | .68 | |||
| Smoking behavior | |||||
| Smoking status | |||||
| Never smoked | 1178 | 316 | 26.8 | Reference | Reference |
| Ever | 277 | 59 | 21.3 | 0.79 (.62–1.01) | 0.86 (.67–1.11) |
| Among smokers, No. of cigarettes/wk | |||||
| 1–5 | 123 | 18 | 14.6 | Reference | Reference |
| 6–20 | 93 | 25 | 26.9 | 1.84 (1.10–3.07) | 1.65 (.97–2.81) |
| >20 | 55 | 13 | 23.6 | 1.62 (.87–3.01) | 1.54 (.80–2.94) |
| P value for trend | .051 | .074 | |||
| Among smokers, age at smoking initiation, y | |||||
| ≤14 | 20 | 7 | 35.0 | 1.55 (.67–3.60) | 2.76 (1.29–5.89) |
| 15–18 | 111 | 19 | 17.1 | 0.76 (.47–1.21) | 0.91 (.55–1.53) |
| ≥19 | 146 | 33 | 22.6 | Reference | Reference |
| P value for trend | .87 | .15 | |||
| BMI at enrollment | |||||
| Underweight (<18.5 kg/m2) | 141 | 48 | 34.0 | 1.37 (1.06–1.78) | 1.46 (1.11–1.92) |
| Normal (18.5–24.9 kg/m2) | 826 | 205 | 24.8 | Reference | Reference |
| Overweight (25–29.9 kg/m2) | 307 | 71 | 23.1 | 0.93 (.73–1.18) | 1.04 (.81–1.33) |
| Obese (≥30 kg/m2) | 181 | 51 | 28.2 | 1.14 (.87–1.48) | 1.20 (.91–1.58) |
| P value for trend | .44 | .78 |
Abbreviations: AFI, age at first sexual intercourse; BMI, body mass index; CI, confidence interval; LNSP, lifetime number of sexual partners; RR, relative risk.
aAdjusted model includes assay (includes all combination of assay of prior incident infection assay of incident infection, and first assay after 300 days—the assay used to declare persistence; SPF10–LiPA25/TypeSeq for each), number of tests between incident and persistent infection (0, ≥1), time between test prior to incident infection and incident infection (using a 3 degrees of freedom [df] cubic spline of log[time]), time between test for incident infection and first test after 300 days (using a 3 df cubic spline of log[time]), visit protocol (Costa Rica Vaccine Trial/long-term follow-up), missed previous visit (yes/no), visit age (using a 3 df cubic spline of age), smoking, oral contraceptive use, age at first sexual intercourse, LNSP, monthly frequency of sexual intercourse since last visit, number of full-term pregnancies, and marital status.
bDiaphragm, sponge, spermicide, intrauterine device, and others.