Patients
Among 1534 patients who participated in this study from April 2021 to
November 2022, 1529 eligible women aged 16 to 39 years (mean age, 30.4 ±
5.5 years) underwent evaluation. The patients visited 11 outpatient
clinics (9 private clinics and 2 hospitals) in 7 districts in Japan
(Hokkaido, Tokyo, Kanagawa, Aichi, Ishikawa, Osaka, and Okinawa) for
various reasons. All patients provided written informed consent prior to
participation in this study. All medical facilities received approval to
participate from their respective independent ethics
committees/institutional review boards. This study was conducted in
accordance with the ethical guidelines for epidemiological research and
the ethical principles of the Declaration of Helsinki.
The present study was performed using the same approach implemented in
the J-HERS performed from October 2010 to March 2012 (21) (Fig. 1).
Therefore, the present study was designated “J-HERS 2021” and the
previous study was designated “J-HERS 2011.” The J-HERS 2011 study was
conducted concurrently with the Japanese national and local governments’
special HPV vaccination program, as depicted in Figure 1. Consequently,
a limited number of participants underwent vaccination during that
study. The interval between the periods included in these two studies
varied from 9 years 1 month to 12 years 1 month.
Analysis of HPV vaccination rates among J-HERS 2021 participants
revealed that the rate was highest among women aged 22 to 27 years.
Therefore, the following age groups were established in the present
study: 16 to 21, 22 to 27, 28 to 33, and 34 to 39 years. Women were
excluded if they had past or present malignant diseases, lacked a
uterus, or had no history of sexual intercourse. The reasons for the
patients’ visits were as follows: cervical cancer screening; follow-up
for abnormal Pap test results, including diagnosis of CIN1/2; and
obstetrics or gynecology consultations including pregnancy diagnosis,
menstrual disorders, sexually transmitted infections, endometriosis,
adenomyoma, uterine leiomyoma, and benign ovarian cysts (Table 1).
We evaluated the age-adjusted data of the 5062 patients who participated
in the previous J-HERS 2011 study for comparison with the patient
population in the present study. We intended to assess the prevalences
of cervical lesions and HPV infection, thus enabling examination of HPV
vaccination effectiveness in the context of the nationwide HPV vaccine
program in Japan, 9 to 12 years after initial implementation. The age
distribution did not differ between the two studies; however, the rates
of visiting for CIN follow-up and obstetrics or gynecology consultations
were significantly higher in J-HERS 2011 than in J-HERS 2021. To avoid
bias related to the different backgrounds between the two studies, only
patients who visited for cervical cancer screening were included in the
analysis (J-HERS 2021, n = 1130; J-HERS 2011, n = 3236).