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Gonorrhea Prevalence and Coinfection With Chlamydia in Women in the United States, 2000

DICKER, LINDA W. PhD; MOSURE, DEBRA J. PhD; BERMAN, STUART M. MD, ScM; LEVINE, WILLIAM C. MD, MScTHE REGIONAL INFERTILITY PREVENTION PROGRAM

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Sexually Transmitted Diseases: May 2003 - Volume 30 - Issue 5 - p 472-475
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Gonorrhea is the second most commonly reported notifiable disease in the United States (U.S.), and reported rates of gonorrhea among women in the U.S. are highest for young women, particularly those aged 15 to 24 years. 1 Gonorrhea, like chlamydia, is often asymptomatic in women and can be detected only through screening;2 thus, the number of reported cases of gonorrhea reflects in part the amount of screening being done.

The Regional Infertility Prevention Program has been supporting chlamydia screening services for women in family planning and other clinic settings since 1993. 3 In the mid- to late 1990s, as laboratory testing technology evolved to include testing for both chlamydia and gonorrhea with a single specimen, many of these clinics began screening women for both diseases. 4 There have been no recent national data on the prevalence of gonorrhea in populations routinely screened for gonorrhea and chlamydia. The purpose of this analysis was to use such data to describe gonorrhea positivity in 2000 in the U.S. among women aged 15 to 24 years. Since the Sexually Transmitted Diseases Treatment Guidelines of the Centers for Disease Control and Prevention (CDC) for 2002 recommend empirical treatment for chlamydia in persons with gonorrhea, 5 we also used these data to examine chlamydial coinfection among young women who tested positive for gonorrhea.

Methods

We analyzed data from chlamydia and gonorrhea tests performed from January 1, 2000, through December 31, 2000, on women aged 15 to 24 years seen in 1290 family planning clinics (449,929 tests), 418 sexually transmitted disease (STD) clinics (86,688 tests), and 247 prenatal clinics (38,155 tests) that participated in the Regional Infertility Prevention Program. The participating clinics in the program collaborate with the CDC on monitoring the prevalence of chlamydial infection among women routinely screened in selected family planning clinics and other provider settings in all states in the U.S. 6 The clinics included in this analysis screened all women 24 years of age and younger for chlamydia and tested 90% or more of these women for gonorrhea, i.e., implemented universal screening for both chlamydia and gonorrhea. Nucleic acid probe assays (Pace 2® and Pace 2C®; Gen-Probe, San Diego, CA) were used to test for gonorrhea in >90% of the specimens tested.

We calculated gonorrhea positivity as the number of positive test results divided by the total number of test results that were either positive or negative. Gonorrhea positivity was calculated for females aged 15 to 24 years (as well as separately for those aged 15 to 19 years and 20 to 24 years) screened at each clinic type (family planning, STD, prenatal) in each state. There were 220,244 tests of females aged 15 to 19 years and 229,685 tests of those aged 20 to 24 years in family planning clinics; 38,728 tests of females aged 15 to 19 years and 47,960 of those aged 20 to 24 years in STD clinics; and 16,498 of females aged 15 to 19 years and 21,657 of those aged 20 to 24 years in prenatal clinics. For each age group and clinic type, we calculated median positivity and the interquartile range (IQR; 25th and 75th percentiles) across the states.

We restricted the analysis of chlamydial coinfection in women with gonorrhea to states from which at least 50 positive gonorrhea tests were reported for the females aged 15 to 24 years who were screened. This was done to ensure a more stable estimate of coinfection. We calculated chlamydia positivity (number of positive chlamydia tests, divided by the number of tests that were positive or negative) among women who tested positive for gonorrhea in each state and clinic type. We examined the median positivity and the IQR across the states for each clinic type.

Results

Gonorrhea Positivity

In 2000, the gonorrhea positivity among females aged 15 to 24 years screened in family planning clinics in 26 states ranged from 0.1% in Vermont to 4.5% in Mississippi (Figure 1). The highest gonorrhea positivity among young women screened in family planning clinics was in southern states. Overall, the median state-specific gonorrhea positivity in family planning clinics was 0.9% (IQR, 0.7%–1.7%) (Table 1). The median positivity was higher among those aged 15 to 19 years than among those aged 20 to 24 years (1.2% versus 0.8%).

Fig. 1
Fig. 1:
Gonorrhea positivity among women aged 15 to 24 years screened in family planning clinics in the year 2000 (*states that did not report gonorrhea positivity data or did not routinely screen 90% or more of the women aged 15 to 24 years for gonorrhea).
TABLE 1
TABLE 1:
Median State-Specific Gonorrhea Positivity Among Women, By Age Group and Clinic Type, 2000

Gonorrhea positivity in STD clinics in 21 states ranged from 0% in Wyoming to 12.8% in Texas (Figure 2). The highest gonorrhea positivity in STD clinics was in the South. Overall in STD clinics, the median state-specific positivity was 7% (IQR, 4.1%–10.4%;Table 1). The median state-specific gonorrhea positivity among females aged 15 to 19 years was 8.1%, compared with 6.5% among those aged 20 to 24 years.

Fig. 2
Fig. 2:
Gonorrhea positivity among women aged 15 to 24 years screened in sexually transmitted disease clinics in the year 2000 (*states that did not report gonorrhea positivity data or did not routinely screen 90% or more of the women aged 15 to 24 years for gonorrhea).

Thirteen states reported universal gonorrhea screening data from prenatal clinics for women aged 15 to 24 years; gonorrhea positivity ranged from 0% in New Mexico and Nevada to 3.7% in Louisiana (Figure 3). The median state-specific gonorrhea positivity was 1% (IQR, 0.8–1.6%) (Table 1). The median gonorrhea positivity among females aged 15 to 19 years was 1.2%, compared with 0.8% among those aged 20 to 24 years in prenatal clinics.

Fig. 3
Fig. 3:
Gonorrhea positivity among women aged 15 to 24 years screened in prenatal clinics in the year 2000. *States that did not report gonorrhea positivity data or did not routinely screen 90% or more of the women aged 15 to 24 years for gonorrhea.

Chlamydial Coinfection

The median chlamydia positivity among women aged 15 to 24 years with gonorrhea was 43.1% in family planning clinics based on data from 18 states (IQR 39.5–45.4%) (Table 2). The median chlamydia positivity in women with gonorrhea was 38.4% in STD clinics based on data from 16 states (IQR 37.0–42.1%). Among women aged 15 to 24 years with gonorrhea, the median chlamydia positivity was 49.2% in prenatal clinics based on data from 3 states (IQR 42.5–52.9%).

TABLE 2
TABLE 2:
Median State-Specific Chlamydia Positivity Among Women With Gonorrhea, By Age Group and Clinic Type, 2000

Almost half of the women aged 15 to 19 years who were infected with N gonorrhoeae were also infected with C trachomatis (Table 2). The median chlamydia positivity among women 15 to 19 years of age with gonorrhea was 46% in family planning clinics and 45.5% in STD clinics. The median chlamydia positivity among women 20 to 24 years of age with gonorrhea was lower than the younger age group, 39.3% in family planning clinics and 32.7% in STD clinics.

Discussion

The median state-specific gonorrhea positivity among women aged 15 to 24 years in 2000 ranged from 0.9% in family planning clinics and 1.0% in prenatal clinics to 7.0% in STD clinics. Gonorrhea positivity was consistently higher among 15 to 19 year olds compared to positivity among women aged 20 to 24 years in all three clinic types. The highest gonorrhea positivity among young women was in Southern states. Among 15 to 19 year old women with gonorrhea screened in family planning, STD, and prenatal clinics, 45% to 50% were also infected with chlamydia. The incidence of chlamydial coinfection among women aged 20 to 24 years with gonorrhea (33%–45%) was lower than in the younger age group but still high.

The overall relatively low positivity for gonorrhea (≤1%) found in family planning and prenatal clinics in 2000 may be a reflection of several factors, including the ongoing gonorrhea screening and treatment program that began in the 1970s, the availability of effective single-dose therapy, and changes in sexual behavior, including increases in condom use. 7 The higher gonorrhea positivity levels in the South are consistent with the higher reported gonorrhea case rates in that region as well as higher rates of other STDs such as chlamydia and syphilis. 1 The higher gonorrhea positivity in all clinic types among females aged 15 to 19 years versus those aged 20 to 24 years is also consistent with the higher reported gonorrhea case rates in this age group. 1 A recent household survey in Baltimore also found that the prevalence of both untreated as well as recently diagnosed gonorrhea was higher among teens than among women in their early 20s. 8

Previous studies have documented high levels of chlamydial coinfection among young women with gonorrhea. Studies in the early 1980s showed that the probability of coexisting chlamydial infection was between 0.26 and 0.48 among women with gonococcal infection. 9 A study of data from 1993 to 1996 showed that 42% of women aged 25 years or younger with gonorrhea that was diagnosed and treated in STD clinic settings were also infected with chlamydia. 10 A more recent study, of health maintenance organization patients in California, showed similarly high rates of chlamydial coinfection (43.4%) among women aged 20 years or younger who were infected with N gonorrhoeae11; rates of coinfection decreased with age.

Our study documented higher rates of chlamydial coinfection among females with gonorrhea aged 15 to 19 years (46%–50%) than among those aged 20 to 24 years (33%–45%).

Although the women screened in family planning and prenatal clinics included in this analysis may not necessarily be representative of all sexually active women in each state, positivity has been shown to be a good measure of prevalence among the young women screened in these clinics; the absolute difference between positivity and prevalence estimates was, on average, <0.5%. 12 Furthermore, the young women screened in these clinics were primarily asymptomatic, and their clinic visits were for reasons unrelated to STDs. Unlike gonorrhea case rates, the gonorrhea positivity measure used in this analysis is not affected by the amount of testing being done, the number of sexually active women in the population, or the completeness of reporting. 13,14 While the gonorrhea case rates are an important measure of the burden of the disease in the U.S., these gonorrhea positivity data from the Regional Infertility Prevention Program provide valuable surveillance data for monitoring gonorrhea prevalence trends.

The relatively low gonorrhea positivity in these age groups in many states in 2000 points to the need to examine risk factors associated with gonorrhea so that effective screening criteria can be developed in areas with both lower and higher prevalence levels. Given that almost half of females aged 15 to 19 years with gonorrhea also had chlamydia, this analysis indicates the continued importance of testing for and presumptively treating chlamydia in those women with gonorrhea.

References

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© Copyright 2003 American Sexually Transmitted Diseases Association