Systematic Review of the Incidence and Prevalence of Genital Warts

Harshila Patel; Monika Wagner; Puneet Singhal; Smita Kothari

Disclosures

BMC Infect Dis. 2013;13(39) 

In This Article

Results

PubMed and EMBASE searches for studies on the epidemiology of AGWs yielded 802 and 1,473 records, respectively, for a total of 2,275 records (Figure 1). After elimination of duplicates, 1,241 records were screened and 1,045 were excluded because the title and/or abstract indicated that they did not report on AGW incidence or prevalence. The remaining 196 studies were examined in full-text for eligibility for this review. Of these, 32 studies met the inclusion criteria: 12 from Europe, 10 from North America (including Mexico), 4 from Asia, 3 from South America, 2 from Australia and 1 multiregional. Screening abstracts from relevant conferences yielded an additional 5 references: 3 from Europe and 1 each from Canada and Japan (Figure 1).

Figure 1.

Literature review.

Studies included in the analysis are summarized in Table 1 and Table 2, on incidence and prevalence, respectively. Each table is subdivided into three categories based on methodology of data collection. Table 3 summarizes data from surveys that asked members of the general population about their history of clinically diagnosed AGWs.

Incidence of Anogenital Warts

Thirteen studies reported the incidence of new cases of AGWs (Table 1), defined as diagnosed for the first time at a consultation with no past symptoms or clinical diagnosis of AGWs[27–30] or cases with no AGW-related claim in the previous 12 months.[31–36] Five studies reported the incidence of recurrent AGWs (Table 1), whose definition varied. It included a previous AGW episode that had resolved,[29,37] an episode occurring more than eight weeks after the last caregiver attendance,[38] or an episode occurring within 12 months of a previous AGW episode (early recurrence) or more than 12 months after a previous episode (late recurrence).[28] Ten studies reported the incidence of any AGWs (Table 1), frequently defined as new and recurrent combined.

In the overall population (males and females combined) the annual incidence of any AGWs (including new and recurrent) ranged from 160 in Spain[29] to 289 in the United Kingdom[38] per 100,000, with a median of 194.5 per 100,000 across four studies (Table 1).[2,27,29,38] The overall annual incidence of new cases ranged from 118 in Spain to 205 in the US per 100,000, with a median of 157 per 100,000 across seven studies.[29,30,32,34–36,38]

The regional distribution of new cases of AGWs per 100,000 population was as follows: 101 to 205 in North America,[31–33,35,36] 118 to 170 in Europe[29,34,38] and 204 in Asia (Table 1).[30]

Among males, the overall annual incidence of any AGWs ranged from 94 in the Netherlands[39] to 331 in England[38] per 100,000 general population, with a median of 195.[2,27,29,38–40] An Italian study[41] reported an incidence outside this range of 10 GW cases diagnosed by GPs per 100,000 males. The reported incidence of new AGWs per 100,000 males per year ranged from 103 among the male population of Quebec, Canada, that is covered by the public drug plan[31] to 168 in England,[38] with a median of 137, across seven studies in Europe and North America that were based on administrative records or chart reviews (Table 1).[29,31–35,38] One prospective study from Hong Kong[30] reported a rate outside this range, at 292 new cases per 100,000 men per year, and another, the multinational prospective HPV in Men study that followed 2,487 men from Florida (USA), Sao Paulo (Brazil) and Morelos (Mexico) with repeated genital examinations reported a new AGW incidence of 235 cases per 100,000 person-years[8] (Table 1). Two studies estimated the rate of recurrent AGWs in males[29,38] (Table 1). One of them (from the UK[38]), defining recurrent AGWs as those with a new medical consultation occurring at least eight weeks after the last AGW-related consultation, reported a rate (163 per 100,000) that was almost as high as that of new cases. The other study (from Spain[29]), defining recurrent cases as "those that had a previous episode", reported a much lower rate of 47 per 100,000 men.

Among studies with the general female population, the reported annual incidence of any AGWs (including new and recurrent) per 100,000 population ranged between 99 among women of all ages in Germany[37] and 251 among 10- to 59-year-old women attending Pap screening in Japan,[42] with a median of 224 (Table 1).[2,27,29,37–40,42,43] The Italian prospective study[41] reported a much lower incidence compared to this range, of four cases per 100,000 females listed with GPs. Annual incidence of new AGWs per 100,000 females ranged between 76 among women of all ages in Germany accounting only for AGWs diagnosed by gynecologists[37] and 191 in another German study taking into account AGWs diagnosed in women aged 10 to 79 years in physician offices and hospitals,[34] with a median of 120.5 (Table 1).[29–35,37,38,43] An Italian study reported an annual incidence of 430 new AGW cases per 100,000 females seen by gynecologists.[28] Incidence of recurrent AGWs ranged between 23 in Germany[37] and 103 in England[38] cases per 100,000 females per year (Table 1).[29,37,38,43]

Among the studies reported above, eight provided data on age-specific AGW incidence for both males and females separately and one for females only (Figure 2).[2,27,31–35,41,43] Among males, incidence peaked in the 25- to 29-year age group in six studies[2,27,31,32,34,35] and in the 20- to 24-year age group in one study,[33] anging between 272 (new cases in the USA[35]) and 740 (new and recurrent cases in Australia[27]) per 100,000 (Figure 2).[2,27,31–35,38] Among females, incidence generally peaked in the 20-year age groups ranging from 338 (new cases in British Columbia, Canada[32]) to 861 (new and recurrent cases in Australia[27]) per 100,000 (Figure 2).[2,27,31–35,43] One study from England, reported a peak incidence of 755 new cases per 100,000 individuals aged 20 to 24 years (males and females combined; not shown in Figure 2).[38] The Italian prospective study (Pasciullo, 2011[41]) reported peak incidence rates outside these ranges: 30 per 100,000 males aged 25 to 34 years and 10 per 100,000 females aged 15 to 24 years. In six of the eight studies that reported data for both genders,[2,27,31–35,41] AGW incidence peaked in a younger age group among females than among males. AGW incidence remained significant in the 30- to 45-year age group, ranging from approximately 110 to 290 per 100,000 among females[2,27,32–35,43] and from 190 to 310 cases per 100,000 among males.[2,27,32–35]

Figure 2.

Age-specific incidence of anogenital warts in males and females.

Prevalence

Overall, AGW prevalence ranged from 0.15% to 0.18% based on administrative databases or chart reviews that used the general population as the denominator (Table 2).[29,32,33]

Among males, prevalence ranged from 0.16% to 0.20% (Table 2).[29,32,33] Prevalence estimates were higher among two studies that were based on genital examination of males from general population samples: 4.1% among heterosexual, sexually active US men (age 18–40 years) who agreed to participate in a prospective epidemiological study and denied a previous history of AGWs[44] and 5.1% (penile condyloma) among males seeking a vasectomy in public clinics in Mexico[45] (Table 2). A lower prevalence (0.06%) was estimated in the Italian prospective study[41] based on males listed with a geographically representative sample of GPs (Table 2).

Among females, prevalence ranged between 0.13% and 0.16% in studies using the general female population as the denominator[29,32,33] and ranged between 0.03% and 0.6% in four studies using the population consulting gynecologists as a denominator (Table 2).[28,41,46,47] In studies based on gynecologic examination of women from the general population or those attending cervical Pap screening,[48–52] reported prevalence ranged between 1.1% in Canada[48] and 4.0% in Hungary,[49] with the exception of married rural women in Vietnam (0.2%)[52] (Table 2).

Self-reported History of Genital Warts

In surveys of general adult populations (Table 3), 0.36% (Slovenia, sexually-active, age 18–49 years[53]) to 12.0% (Iceland, age 18–45 years[54]) of females reported a lifetime history of genital warts.[53–59] The corresponding proportion in the male population varied from 3.6% to 7.9% in Australia, Denmark, the UK and the USA and was 0.27% in Slovenia (Table 3).[53,55–57,60] An AGW history in the last 12 months was reported by 0.3% of females in Australia,[55] 1.0% to 1.9% of females in the Nordic countries[54] and 1.2% of males and 2.0% of females in China[61] (Table 3).

Comparison Between Males and Females

Among thirteen studies based on retrospective administrative databases or medical chart reviews, prospectively collected physician reports or genital examinations providing incidence or prevalence estimates for both sexes, nine reported higher rates for males than for females ( Table 1 and Table 2 ).[2,29–33,38,40,41] However, in surveys that included both genders, more females than males admitted ever having had AGWs ( Table 3 ).[53,55–57,61]

Temporal Trends

Five studies[31,32,36,39,54] provided data with respect to temporal trends of AGW epidemiology shown in Figure 3. A population-based study from British Columbia, Canada, reported that the annual AGW incidence increased significantly from 107 per 100,000 in 1999 to 126 in 2006 (P < .0001); increases were observed among both males and females.[32] Prevalence also increased during this time period from 0.11% to 0.15% (P < .001). Another study of individuals covered by the public drug plan in Quebec, Canada reported that the annual AGW incidence increased from 83 to 103 per 100,000 among males from 1998 to 2007 whereas among females, it increased from 86 to 98 per 100,000 from 1998 to 2002.[31] A US study evaluating health claims from privately insured individuals reported an increase in AGW claims from 118 (95% CI 110–126) to 205 (95% CI 199–211) per 100,000 person-years at risk from 1998 to 2001, representing an increase of greater than 70%.[36] A study in the Netherlands observed a significant linear increase in AGW diagnoses from 2002 to 2007 (no P value provided), particularly those diagnosed by general practitioners.[39] Using self-reported data from a random sample of the general female population in Denmark, Sweden, Norway and Iceland born between 1958 and 1986, Kjaer and colleagues[54] found that the age-specific cumulative incidence, estimated based on age at first diagnosis, increased with each subsequent younger birth cohort (P < .01), an effect that was most pronounced in Iceland and Norway (not shown in figure).

Figure 3.

Temporal trends in the incidence of anogenital warts. GP: general practitioner; STI: sexually transmitted infection.

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