EFFECT OF HPV VACCINE ON PREEXISTING HPV INFECTION
in the control group) were not in- cluded in the present evaluation be- cause they were not sexually experi- enced at enrollment (n = 1591) or because a pelvic examination could not be performed for other reasons (n=3). An additional 110 women (60 in the HPV vaccine group and 50 in the con- trol group) were excluded because of evidence of high-grade squamous in- traepithelial lesions or more severe dis-
ease at study entry that resulted in a re- ferral to colposcopy for evaluation and possible treatment. This group was ex- cluded to avoid any effect of exci- sional treatment on viral persistence. Of the 5758 participants remaining, 2376 (41.3%; 1194 in the HPV vac- cine group and 1182 in the control group) were positive for HPV DNA at study entry by SPF10/LiPA or by the type-specific HPV-16/18 primer PCR.
Species alpha-7 excluding HPV-18
Species alpha-9 excluding HPV-16
Other oncogenic HPV
HPV Vaccine Group (n = 1088)
Control Group (n = 1101)
288 (26.5) 295 (27.1) 263 (24.2) 241 (22.2)
313 (28.4) 278 (25.2) 284 (25.8) 226 (20.5)
333 (30.6) 298 (27.4) 456 (42.0)
325 (29.7) 315 (28.8) 455 (41.6)
755 (69.6) 329 (30.4)
796 (72.6) 301 (27.4)
926 (85.1) 162 (14.9)
941 (85.5) 160 (14.5)
642 (59.0) 446 (41.0)
614 (55.8) 487 (44.2)
38 (33-49) 175 (162-200) 365 (321-398)
Data are expressed as No. (%) of participants unless otherwise indicated. Data include all women evaluated in the 6-month and/or 12-month analyses, including 134 women evaluated in the 12-month analysis only. One woman from the HPV vaccine group was 26 years old at entry; 7 women (1 from HPV vaccine group and 6 from control group) had missing information on lifetime number of sexual partners; 8 women (4 from HPV vaccine group and 4 from control group) had missing cytologic results. Referral to colposcopy after trial entry based on evidence of low-grade squamous intraepithelial lesion or HPV- positive atypical squamous cells of uncertain significance at entry and at the 6-month visit or evidence of high-grade squamous intraepithelial lesion or more severe disease at the 6-month visit. Numbers in the HPV analysis groups add up to more than the total number of women because some women had multiple infections. Percentages were calculated at the infection level.
Table 1. Participant Characteristicsa
Vaccination doses received Dose 1
Dose 2 Dose 3 All 3 doses
Follow-up time, median (interquartile range), d
From entry to 1-mo visit (n = 1034/1035) From entry to 6-mo visit (n = 1032/1023) From entry to 12-mo visit (n = 825/846) Abbreviation: HPV, human papillomavirus.
36 (33-49) 177 (163-199) 365 (319-398)
Lifetime No. of sexual partners 1
Costa Rican cytologic findings at entry Normal
Age at entry, y 18-19
20-21 22-23 24-25
Abnormal Referral to colposcopy after entry
HPV infection status Single infection
Multiple infections HPV analysis group c
Individual typing was not obtainable for an additional 455 women (7.9%) (ie, SPF10-positive/LiPA-negative and nega- tive by type-specific HPV-16/18 primer PCR); these women were not in- cluded in the main analyses because evaluation of viral clearance requires knowledge of the specific HPV types in- volved. Of the 2376 women positive for HPV by SPF-10/LiPA at entry, 321 (162 in the HPV vaccine group and 159 in the control group) were excluded from the main analyses because they did not have HPV PCR results available from their 6-month visit. Polymerase chain reaction results were missing for these 321 women because of missed visits (n = 285) or study discontinuations (n=33) or because PCR results were not yet available from the testing labora- tory (n=3).
Compared with women included in the analysis, the 321 excluded women tended to be slightly younger (mean age, 20.6 years for those excluded vs 21.3 years for those included; P.001) but were comparable with respect to mean lifetime number of sexual part- ners (P=.12), frequency of abnormal cy- tologic findings at entry (P=.64), pro- portion of individuals with multiple infections (P=.16), and distribution of HPV analysis groups (P=.29). A lower rate of referral to colposcopy after en- try was observed among those ex- cluded from the analysis (5.9% vs 15.7% among those included; P.001). These 321 women were comparable by group with respect to age (P=.34), lifetime number of sexual partners (P=.54), pro- portion of participants referred for col- poscopy during follow-up (P=.25), pro- portion of individuals with multiple infections (P=.70), and distribution of HPV analysis groups (P=.25). A small increase in the rate of abnormal cytol- ogy at entry was observed in the HPV vaccine group (36.6% vs 25.2%; P=.03).
The final number of women in the HPV PCR–based analyses was 2055 (1032 in the HPV vaccine group and 1023 in the control group; P = .84). These 2055 women had a total of 3467 infections at entry (1730 in the HPV vaccine group and 1737 in the control
748 JAMA, August 15, 2007—Vol 298, No. 7 (Reprinted)
©2007 American Medical Association. All rights reserved.