Prevalence of Genital Human Papillomavirus Infections in a Mass-Screened Finnish Female Population Aged 20–65 Years

Abstract

The results of the nationwide, population-based cervical cancer screening programme (organized by the Finnish Cancer Society since early 1960s) were analysed to establish the prevalence figures (and their changes) for genital human papillomavirus (HPV) infections in an unselected Finnish female population (aged between 20 and 65 years) screened in Kuopio Province between 1981 and 1989. During the study period 82,393 women were invited on a regular basis for the mass-screening, and also 4131 women in a risk group. Of these, a total of 63,115 and 3249 women attended, resulting in the attendance rates of 76.6% and 78.6%, respectively. As a result of the screening, a total of 509 (0.80%) of the 63,115 smears were diagnosed as having the cytological changes consistent with HPV infection in the mass screening. The corresponding figures in the risk group screening were 58/3249 (1.78%). There was a sharply increasing trend in the prevalence of genital HPV infections from 1981 through 1987, from 0.04% to 1.76% (ie a 44-fold increase in 7 years) which, surprisingly, then declined to 1.43% in 1988 and 1.04% in 1989. Based on a random sample of 2084 routine (non-mass-screening) Pap smears (out of 28,861) collected from the files of our laboratory, the prevalence of HPV infections was stratified by age groups. The highest prevalence (6.1%) was observed in women aged between 20 and 29 years, followed by 2.2% in those aged 30–39 years. Using the figures of the relative risk (RR) of HPV infections by age, an estimation was made to assess the prevalence of clinical HPV infections in the Finnish female population in general. With the annual number of female births (approximately 30,000), it was estimated that some 18,000 women aged between 20 and 29 years will harbour a clinically manifest genital HPV infection. It is noteworthy that the above established figures do not include any data of the subclinical and latent HPV infections, not detectable by the Pap smear. Beyond any doubt, genital HPV infections are the most frequent STD in Finland.