EXTERNAL GENITAL WARTS, also known as condylomata acuminata, are caused by infection with human papillomavirus (HPV), a virus regarded as the cause for one of the most common sexually transmitted diseases (STDs) in the United States. 1–3 At least 80 characterized strains of HPV exist, approximately 30 of which are known to cause genital infections. 4,5 However, condylomata are known to be caused predominantly by HPV types 6 and 11, also known as the “low-risk” types, termed thus because they are not believed to contribute to malignant cellular changes. 6
By some estimates, the incidence of visible condylomata acuminata approaches 0.5% to 1% in sexually active or young adults in the United States. 7 In fact, a 1996 report by the Centers for Disease Control and Prevention (CDC) estimated that 24 million Americans are infected with HPV, and that 500,000 to 1 million new cases of HPV-induced condylomata acuminata occur annually. 1 In one large study of adolescent women at urban clinics in Denver, Colorado, HPV was the most commonly found STD in that population, as measured by HPV DNA samples. 8
Multiple studies also have shown that the incidence of subclinical infection from HPV far exceeds the incidence of symptomatic infection, with several polymerase chain reaction DNA analysis studies indicating a subclinical infection rate of 40% or more in their study populations. 9–13 Most epidemiologic studies indicate that adolescents, young adults, and persons with multiple sexual partners are at greatest risk for infection. 2,14
Some reports suggest that women are at a higher risk than men for acquiring this infection, although no consensus on this point exists. 4,5 This observation may be confounded by the observation that women routinely seek genital examinations during the years when they are at highest risk for STDs, whereas men do not often seek such care. Data on the racial demographics of condylomata appear to be conflicting as well. 15,16
The primary purpose of this study was to characterize healthcare service use for condylomata acuminata better in terms of patient demographics and treating physician specialty using a national probability sample. This study also tried to describe how condylomata relate to noncondylomatous warts in terms of these factors.
This study used data from the National Ambulatory Medical Care Survey (NAMCS) for the years 1994 to 1998. The NAMCS is a continuous-sample survey conducted by the US Department of Health and Human Services and the National Center for Health Statistics. It represents an attempt to characterize outpatient care by non–federally funded physicians in the United States. 17
The NAMCS uses a multistage probability sample design involving samples of primary sampling units, physician practices within primary sampling units, and patient visits within physician practices. This survey contains data on individual visits to office-based physicians, which then are weighted to reflect national estimates describing the use of ambulatory medical care services in the United States.
The visit to an office-based physician is the basic sampling unit for the NAMCS. Nonfederal physicians classified by the American Medical Association (AMA) or the American Osteopathic Association (AOA) as fulfilling office-based, patient care, including all physician specialties except anesthesiology, pathology, and radiology, are included in the NAMCS. Data collection involves physicians or office staff who complete a patient record form providing the patient’s reason for visit classification (chief symptom), diagnoses (coded by the International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]), demographic data, services provided, and referral practices. In small practices, 100% of the patient visit data are available, whereas in very large practices, 20% of the patient visits are sampled randomly. Patient visits are sampled during a randomly assigned 1-week reporting period.
During the sample period 1994–1998, there were an estimated 20,106,428 patient visits for noncondylomatous warts and an estimated 3,036,376 visits for condylomata based on 926 and 133 records, respectively, obtained from the NAMCS. Any visits during which warts or condylomata were identified as the primary, secondary, or tertiary diagnoses by the ICD-9-CM were included in the data set for this study. The ICD-9-CM codes represented different warts as follows: 078.10 (viral warts not otherwise specified), 078.11 (condylomata acuminata), and 078.19 (other warts), or 107810, 107811, and 107819, respectively, during 1994. Review of the coding by different physicians showed that obstetrician/gynecologists (Ob/Gyn) and urologists coded a significant number of warts as noncondylomatous types.
On the basis of the notion that Ob/Gyns and urologists would see genital disorders almost exclusively, we assumed that any designations of “viral warts not otherwise specified” or “other warts” by these two subspecialists actually represented condylomata. By doing so, we increased the number of visits for condylomata from an estimated 925,657 visits (50 records) to the aforementioned estimate of 3,036,376 visits (133 records). This difference was important for Ob/Gyns, for whom the number of estimated condylomata visits increased from 203,000 (10% of Ob/Gyn wart visits; 10 records) to 2,039,000 (100% of Ob/Gyn wart visits; 69 records). Analogously, for urologists, the number of estimated condylomata visits increased from 55,000 (17% of urology wart visits; 6 records) to 331,000 (100% of urology wart visits; 30 records). It should be noted that NAMCS diagnoses are written by physicians, and the ICD-9-CM diagnosis code is inferred from the written diagnosis.
Next, we constructed a data set that included warts coded by physicians as ”viral warts not otherwise specified“ or ”other warts“ as the noncondylomatous type. That is, we constructed two data sets, one describing patient visits for condylomata and the other describing visits for all other warts (i.e., noncondylomatous warts).
To qualify patient profiles, we examined factors including patient age, gender, and race. Age was examined as frequency of visits in 10-year increments (e.g., 0–9 years, 10–19 years). Race included four categorizations: white, black, Asian and Pacific Islander, and Native American, Eskimo, or Aleut. For a better characterization of visits relating to racial demographics, per capita visits for blacks and whites seen for both condylomata and noncondylomatous warts were calculated. This was accomplished by dividing the total yearly visits of either blacks or whites with either condylomata or noncondylomatous warts by the thousands of either blacks or whites in the population. Population data were obtained from the US Census Bureau estimates for the year 1996, which corresponded to the middle year of the NAMCS data interval. 18 To calculate the per capita number of condyloma visits for specialties, midpoint (1996) estimates for the number of physicians were obtained from the National Center for Health Statistics.
Data analysis and synthesis were performed by the SAS system (SAS Institute, Cary, NC) and Stata (Stata Corp., College Station, TX). The relative standard errors calculated in this study, and thus the confidence intervals presented in this report, were based on the size of each estimate. In these calculations, each observation’s sample weight was taken into account.
According to the aforementioned coding scheme, during the sample period 1994–1998, an estimated 600,000 physician visits per year for condylomata and 4 million visits per year for noncondylomatous warts occurred.
The estimated the proportion of visits (95% CI) for age distribution showed that healthcare use peaked for patients with condylomata in the age intervals 20 to 29 years and 30 to 39 years, representing 35% (95% CI 25–45) and 36% (95% CI 27–47) of total, respectively (Figure 1). Notably, the group 0 to 9 years old accounted for no physician visits. Healthcare use for noncondylomatous patients demonstrated a different distribution. The peak in this category occurred in the 10- to 19-year-old age group, accounting for 32% (95% CI 28–36) of the total. The 0- to 9-year age range accounted for 13% (95% CI 11–16), and the 20- to 29-year, 30- to 39-year, and 40- to 49-year age ranges had rates near 13% as well. The mean age of patients visiting for condylomata 33.2 years (95% CI, 30.9, 35.5) was comparable with the mean age of patients visiting for noncondylomatous warts 30.6 years (95% CI 29.3, 31.88). If the most restrictive ICD-9-CM coding is used for condylomata and noncondylomatous warts (i.e., assuming urologists and gynecologists treated patients with common warts and plantar warts), the mean age for condylomata changes only slightly to 35.3 years (95% CI, 31.2, 39.32), and for noncondylomatous warts to 30.7 years (95% CI, 29.5, 31.91).
In terms of gender distribution, females accounted for 67% (95% CI 57–75) of physician visits for condylomata, and males accounted for 33% (95% CI 25–43) of such visits. Noncondylomatous wart healthcare use demonstrated a more equal distribution, with females accounting for 53% (95% CI 49–57) and males for 47% (95% CI 43–51) of the total visits. According to χ2 analysis, a significant difference (P = 0.003) exists between male and female healthcare use for condylomata versus noncondylomatous warts.
Analysis of racial healthcare use for warts showed that for whites, 88% (95% CI 85–90) of all wart visits were for noncondylomatous warts, and that 12% (95% CI 10–15) were for condylomata. For blacks, 60% (95% CI 47–75) of all office visits were for noncondylomatous warts, and 40% (95% CI 25–58) for condylomata. Of Asians using health care for wart diagnoses, 98% (95% CI 88–100) were seen for noncondylomatous warts and 2% (95% CI 0–12) for condylomata. Per capita visits for condylomata in blacks and whites were equal, with 2.4 visits per thousand persons per year. However, healthcare use for noncondylomatous warts showed that the per capita rate for whites was almost five times higher (17.3 versus 3.6) than for blacks.
Examination of healthcare use for warts by physician specialty showed that for condylomata, Ob/Gyn was used most (67%; 95% CI 58–76), followed by dermatology (14%; 95% CI 27–36) and urology (11%; 95% CI 7–16). Physicians used most for noncondylomatous warts included dermatologists at (47%; 95% CI 43–51), general or family practitioners (31%; 95% CI 27–36), and pediatricians (9%; 95% CI 8–12) (Table 1). The per capita number of visits to physician specialists over the study interval by specialty were as follows: general or family practitioner 3.4 visits, Ob/Gyn 71 visits, dermatology 61 visits, urology 42 visits, and all other specialties combined 0.14 visits.
Analysis of our study data indicates that women, with 67% of the total condylomata visits, are significantly more likely to use health care for condylomata than men. By contrast, for noncondylomatous warts, healthcare use is nearly equal for males and females. The current finding of nearly equal gender-based use of health care for noncondylomatous warts agrees with a study by Rubben et al, 19 which found no gender differences in persons affected by common warts.
The current data on healthcare use for condylomata are in agreement with numerous prevalence reports. Chuang et al, 4 in Rochester, Minnesota, found that after adjustment for gender distribution, more women than men had visible condylomata acuminata at a rate of 1.4 to 1. The CDC study from 1966 to 1981 found that most age groups had more female patients, and that 62% of all visits to physicians for condylomata in 1978 were by females. 5 A possible explanation for these findings is that females are more likely to be infected, and hence more likely to use health care. 4 This difference may be explained partly by the different types of epithelium exposed during male–female sexual intercourse. The difference also may be explained partly by other gender-based differences that may make women more willing to seek health care for condylomata. The notion that women are more likely than men to seek genital examinations on a regular basis as part of routine health care also could explain the gender bias found in healthcare use for condylomata.
Additionally, gender differences in treatment efficacy could explain the observed healthcare use differences. Treatment efficacy differences that lead to more female return visits may be an additional explanation for the higher proportion of females using healthcare services for condylomata. Interestingly, topical imiquimod, a new treatment released after our NAMCS data interval, has proved more effective in women than men. 20 If treatment efficacy differences are indeed responsible for gender differences in healthcare use, widespread use of this new therapy may equilibrate the distribution to some degree.
The data from this study, demonstrating that the 20- to 39-year-old interval accounted for more than 70% of the total visits, confirms numerous epidemiology reports. A 1983 CDC report states that in 1981, 65% of the consultations for condylomata acuminata were in the 15- to 29-year-old range. 7 The highest risk in this study was for the 20- to 29-year-old group, which accounted for 56% of the total visits. This is consistent with the current data, which shows that the 20- to 29-year-old group accounts for 35% of the total visits. Chuang et al 4 reported in 1984 that between 1950 and 1978 in Rochester, Minnesota, 80% of patients with condylomata were between 17 and 33 years of age. Koutsky 2 reported in 1997 that the highest rates of genital HPV infection are found in adults 18 to 28 years of age.
Our data also demonstrate that beyond the age of 39 years, healthcare use for condylomata decreases as age increases, which is consistent with other reports in the literature. Tortolero-Luna 16 reported that an inverse association between age and HPV prevalence exists worldwide. The most likely explanation for this distribution of HPV seems to implicate age patterns for first sexual intercourse.
Additionally, the current study demonstrated that the 0- to 9-year-old group accounted for no physician visits, which is consistent with findings elsewhere that condylomata acuminata are rare in the general pediatric population. 1 However, because condylomata acuminata do occur, although uncommonly, in this population, this finding represents a limitation of this study with its use of a national probability sample.
Our study showed that racial use of health care for condylomata was essentially equal in terms of per capita visits. Both blacks and whites had 2.4 visits per thousand persons per year. Reports on racial demographics for condylomata are conflicting. In 1988, Koutsky et al 15 cited two studies indicating that the frequency of condylomata is higher among whites than among nonwhites. Tortulero-Luna 16 reported several studies indicating that blacks have higher prevalence rates for HPV than whites or Hispanics. Reasons for such a disparity may include racial differences in innate susceptibility, acquired immunity, behavior, detectability, or socioeconomic status. However the current data suggest that, on the basis of per capita similarities in healthcare use, such differences may not exist for condylomata. For noncondylomatous warts, however, the current data indicate that whites had nearly five times more per capita visits than blacks. The explanation for such a disparity may lie in the reasons cited earlier for differences among races in healthcare use for condylomata.
In terms of physician specialty used for condylomata, the current study found that Ob/Gyn was the most frequently consulted specialty, followed by dermatology, urology, and family or general practice. The visits for noncondylomatous warts were led by dermatology, family or general practice, and pediatrics. These findings are similar to those of the CDC study in 1981, which found that Ob/Gyn, dermatology, and general or family practice, in this order, were the most frequently consulted specialties for condylomata. The study also found that 54% of females consulted Ob/Gyn, whereas the largest percentage of males consulted in the specialty of dermatology, with family or general practice, internal medicine, and urology handling sizable percentages. 5 The current findings confirm the observation that in the nearly two decades since the CDC report, no difference has been found in the types of physicians consulted for condylomata.
However, the findings from the current study show that there is a sizable difference between specialties in their per capita number of visits for condylomata. Many studies in other areas of medicine have found that the quality of medical care is related to the number of cases managed or patients seen. 21–32 To maintain or obtain expertise in treating a condition such as condylomata, it is not apparent how many cases a treating physician should see over time. Nevertheless, it can be hypothesized that treating one patient or less per year may not be adequate to maintain expertise. This finding has major policy implications.
A major limitation of this study is that the NAMCS does not include visits to public health, hospital inpatient, or military medical facilities. Therefore, it is difficult to estimate the total number of consultations in the United States for condylomata acuminata. Also, because the NAMCS is limited to nonfederally employed physicians principally engaged in outpatient care activities, some selection bias or sampling error may be inherent. One of the most important limitations of the current study is that the relatively small sample size limits subset analysis. As a result, differences in treatment patterns between physician specialties and gender-related differences cannot be characterized further.
The uncertain accuracy in ICD-9-CM coding also may further limit the data obtained. It is important to note that the current data indicate only the importance of visible condylomata among patients visiting private practitioners. Studies that rely on visible evidence of condylomata acuminata may represent only the tip of the iceberg in terms of actual HPV prevalence. This is partly because genital HPV seems to run a fluctuating course, changing from clinical to subclinical over various time intervals. 16 As studies proceed from visible condylomata acuminata to colposcopy/cytology to DNA assays, the the prevalence of HPV infection is shown to increase. 2 The current data were derived exclusively from visits for clinically evident (visible) condylomata.
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