Untreated Gonococcal and
Chlamydial Infection in a Probability Sample of Adults
JAMA. 2002;287:726-733
Charles F. Turner, PhD; Susan M. Rogers, PhD; Heather G. Miller, PhD;
William C. Miller, MD, PhD; James N. Gribble, ScD; James R. Chromy, PhD; Peter
A. Leone, MD; Phillip C. Cooley, MS; Thomas C. Quinn, MD; Jonathan M. Zenilman,
MD
Context The prevalence and distribution of gonococcal and chlamydial
infections in the general population are poorly understood. Development of
nucleic acid amplification tests, such as the ligase chain reaction assay,
provides new opportunities to estimate the prevalence of untreated infections
in the population.
Objective To estimate the overall prevalence of untreated gonococcal and
chlamydial infections and to describe patterns of infection within specific
demographic subgroups of the young adult population in Baltimore, Md.
Design and Setting Cross-sectional behavioral survey based on a probability sample of
Baltimore households with collection of urine specimens between January 1997
and September 1998.
Participants A total of 728 adults aged 18 to 35 years completed the interview
portion of the study, and 579 of these respondents also provided a urine
specimen adequate for testing.
Main Outcome
Measure Prevalence of untreated
infection, as measured by the percentage of specimens testing positive for
gonococcal and chlamydial infection by ligase chain reaction, weighted to
reflect variations in probabilities of sample selection from the population.
Alternate estimates of the prevalence of recent treated infection were derived
from clinically diagnosed cases reported to the Baltimore City Health
Department and by diagnoses reported by participants in the survey.
Results An estimated 5.3% (SE, 1.4%) of the population aged 18 to 35 years
has an untreated gonococcal infection, and 3.0% (SE, 0.8%) is estimated to have
an untreated chlamydial infection. While 7.9% (SE, 1.6%) of the population is
estimated to have either an untreated gonococcal or chlamydial infection,
estimated prevalence is substantially higher among black women (15.0%; SE,
3.7%). Few participants with untreated infections reported dysuria or discharge
during the 6 months preceding testing. The estimated number of untreated
gonococcal infections in the population (9241; SE, 2441) substantially exceeds
both the number of such infections diagnosed among Baltimore adults aged 18 to
35 years and reported to the Baltimore City Health Department during 1998
(4566), and the estimated number of diagnoses derived using participants'
reports for the 12 months prior to the survey (4708 [SE, 1918] to 5231 [SE,
2092]). The estimated number of untreated chlamydial infections (5231; SE,
1395) is also greater than the number of cases reported to the health department
in 1998 (3664) but is slightly less than the estimated number of diagnoses
derived using participants' reports of chlamydial infections diagnosed during
the 12 months prior to the survey (5580 [SE, 1918] to 6975 [SE, 2441]).
Conclusion In 1997-1998, the estimated number of undiagnosed gonococcal and
chlamydial infections prevalent in the population of Baltimore adults aged 18
to 35 years approached or exceeded the number of infections that were diagnosed
and treated annually.
JAMA. 2002;287:726-733
Untreated infection with Neisseria gonorrhoeae or Chlamydia trachomatis can result in
chronic pelvic pain, infertility, and potentially fatal ectopic pregnancies among
women. In addition, these bacterial sexually transmitted diseases (STDs) serve
as biological cofactors that facilitate transmission of human immunodeficiency
virus (HIV). Untreated chlamydial infections, for example, are estimated to
increase the likelihood of HIV transmission by a factor of 1.4 to 3.3.1-3
Unfortunately, the prevalence and distribution
of these STDs within the population are poorly understood. Until recently, our
knowledge was limited by its exclusive dependence on 2 data sources with
well-recognized inadequacies
the counting of
infections reported to public health departments and studies of convenience
samples of special populations, such as clinic patients. While these sources
can provide useful information, they are inherently incapable of characterizing
untreated STD infection in the population at large. This problem is
particularly severe for infections whose symptoms are mild or nonexistent.
Available evidence suggests that a substantial fraction of gonococcal and
chlamydial infections are asymptomatic.4-8 The Institute of
Medicine has noted,8 such STDs spawn "
. . . hidden epidemics of tremendous health and economic consequence in the
United States . . . [T]he scope, impact, and consequences of [these] STDs are
underrecognized by the public and health care professionals."
The recent development of nucleic acid
amplification tests (NAATs) for the diagnosis of gonococcal and chlamydial
infections using urine specimens has generated new models for research on the
epidemiology of these STDs.9-11 Since the urine
specimens required for NAAT can be obtained in population surveys, generalizations
about the prevalence and patterns of infection now can be derived from surveys
of probability samples of the general population rather than samples of clinic
patients or other special populations. This research model provides estimates
(with known margins of sampling error) for the prevalence of untreated
infections both in the population at large and in identifiable subpopulations.
To provide a more accurate understanding of the
hidden epidemics of untreated infection with N
gonorrhoeae and C trachomatis,
using probability sampling methods, we recruited a population sample of young
adults aged 18 to 45 years to participate in a survey of sexual and other
sensitive behaviors and STD history. We then used NAATs of urine specimens
obtained from survey respondents aged 18 to 35 years to detect the presence of
untreated gonococcal and chlamydial infections. The resultant data allowed us
to estimate the prevalence and patterns of untreated infection in our target
population, adults aged 18 to 35 years in Baltimore, Md.
METHODS
Sample Design
The sample for the Baltimore STD and Behavior Survey was drawn from households
residing within the municipal boundaries of the city of Baltimore (1998
population: 645 664).12 Households were
selected using a stratified probability sampling design that selected
residences from the Baltimore Real Estate Property Registry. This registry
includes all propertiesboth taxable and
tax-exemptwithin the city of
Baltimore. Two sample strata were disproportionately sampled to ensure adequate
representation of (1) young black men and (2) young adults living in
predominantly white US Census tracts with elevated levels of STDs (based on
Baltimore City Health Department [BCHD] STD surveillance statistics).
Operationally, these 2 strata comprised (1) households with an age-eligible man
drawn from census tracts with 95% to 100% black residents according to the 1990
US Census; and (2) adults aged 18 to 35 years residing in 13 census tracts that
had the highest rates of reported gonococcal infection among tracts with 0% to
9% black residents. A third crosscutting sample stratum was created to accommodate
the refielding of a 50% random subsample of cases for which our quality control
procedures could not verify the integrity of the interview data (see below).
This sample design oversampled segments of the
population that are known to have higher rates of STDs (ie, young black men and
whites living in US Census tracts with high rates of reported STDs).
Oversampling is routinely used in household surveys to ensure adequate sample
sizes for difficult-to-survey or numerically rare segments of the population.
Probability sampling requires that every member of the population have a
nonzero probability of selection. Complex probability samples use
stratification and sampling at different rates in the design stage and sample
weighting (by the inverse of the sampling probabilities) at the analysis stage
to yield samples representative of the targeted population. Our prevalence
estimation uses sampling weights to adjust for the unequal probabilities of
selection across sample strata.
Informed Consent
A 2-stage procedure was used to obtain informed consent. Informed consent (both
oral and written) was first obtained from all survey participants (aged 18-45
years) prior to the survey interview. A separate consent (both oral and
written) was obtained from respondents (aged 18-35 years) participating in the
urine testing. The informed consent process made explicit that the urine would
not be used for drug testing and that, in compliance with state laws, specimens
found positive for gonococcal and/or chlamydial infection would be reported to
the BCHD. The protocol for this study was approved by institutional review
boards at the Research Triangle Institute and Johns Hopkins Medical
Institutions.
Interview
Respondents completed a detailed survey on sexual behavior, prior STD history,
STD symptoms, drug and alcohol use, social attitudes and behaviors, and
individual background characteristics. Interview data were collected by 36
trained interviewers in the respondent's home. Interviewers were instructed to
conduct the interviews in a private place in the home or at an alternate
location where privacy could be ensured. They were specifically instructed that
they could not conduct an interview if another person was listening. To satisfy
another objective of the research program, respondents were randomly assigned
to complete the survey questionnaire using either traditional survey procedures
(ie, computer-assisted personal interview with some paper-and-pencil
self-administered questionnaires) or an audio computer-assisted
self-interviewing technology.13-15 (Random assignment
of respondents to interview modes ensures that there will be no systematic
association between interview mode and the variable of central interest to us NAAT-diagnosed gonococcal
or chlamydial infection.) Data from these 2 interview modes are aggregated in
this article. The survey took an average of 26 minutes to complete. Respondents
received $10 to $20 at the conclusion of the interview.
Collection and Processing of
Urine Specimen
At the conclusion of the interview, participants aged 18 to 35 years were asked
to provide a urine specimen for testing. Respondents who agreed to provide a
urine sample for screening received an additional $10 to $20.
N gonorrhoeae and C trachomatis
were detected in urine specimens using a ligase chain reaction (LCR) assay
(Abbott Laboratories, North Chicago, Ill). The LCR assay was performed
according to the manufacturer's instructions. Positive test results were
reconfirmed by a repeat analysis using this same procedure. If this second
analysis was negative, the case was coded as negative. (Repeat analyses were
not available for 3 cases that tested positive on initial testing. These cases
were coded positive based on their initial testing.)
Notification of Results
All respondents were given a telephone number they could call to learn of their
test results, and study staff used a succession of methods to attempt to
contact participants who tested positive (telephone, registered letter, and, if
refused or undelivered, regular mail). Free, expedited treatment at one of the
BCHD clinics was offered to all contacted subjects who tested positive.
Quality Control
During the course of the study, a subset of interviewers' work was subject to
independent verification to confirm that the interview had been completed and
that a urine specimen had been requested if the respondent was 35 years or
younger. A verification interviewer (not part of the regular survey staff)
contacted the household to confirm the respondent's name, participation in the
survey, demographic information, date of interview, whether a urine specimen
had been collected, and whether the respondent had been paid the monetary
incentive. This procedure identified 7 interviewers who appeared to have
fabricated some of their interviews or to have collected interview data and
urine specimens from households other than those selected into the sample. All
of the interviews submitted by these interviewers were subject to verification,
and data were retained only if the verification result was positive. (A full
account of these procedures has been presented elsewhere.16)
Over the course of the study, 56% of all
completed survey interviews included in the final database were subject to
independent verification.
Statistical Analyses
Prevalence estimates were derived using case weights that are inversely
proportional to the probabilities of case selection and that incorporate a
poststratification weighting to ensure that the sample distribution matched the
1997 US Census tabulation of the Baltimore population by race, sex, and age.
Statistical algorithms that take account of the impact of complex sample
designs on variance estimates, as implemented in the survey data component of
Stata 6.0,17, 18 were used in all
analyses and calculation of variance estimates. We tabulated frequencies of
demographic characteristics to obtain a descriptive profile of the sample.
Logistic regression and 
2
tests were used to assess the association between estimates of infection status
and other subject characteristics. Tests of the equivalence of prevalence
estimates for gonoccocal vs chlamydial infections take account of the
covariance that arises when estimates are derived using measurements made on
the same subjects.
Impact of Assay Performance on
Estimated Prevalence
To assess the potential impact of assay performance on prevalence estimates,
sensitivity analyses were conducted using a plausible range of estimates for
the specificity (0.990-0.999) and sensitivity (0.90-0.94) of the LCR assays
used in this research. Past research indicates that NAAT assays have high
sensitivity (>0.90) and specificity (>0.99) for the detection of
chlamydial and gonococcal infections because genetic material from the target
organisms is detected.19-24 In the present
study, specificity was optimized by retesting almost all positive specimens and
considering a specimen positive only if both initial and repeat test results
were positive. Sensitivity analyses were performed using spreadsheets
constructed in Excel 2000 (Microsoft, Redmond, Wash).
Impact of Missing Data on
Estimated Prevalence
To assess the impact of respondents' refusal or inability to provide urine
specimens on our prevalence estimates, we used logistic regression to model the
likelihood that respondents would test positive for either gonococcal or
chlamydial infection based on a range of sociodemographic and behavioral variables
collected in the survey interview. This model was estimated using data from
those respondents who provided urine samples adequate for testing. The
parameter estimates derived for this model were then used to impute the
probability that individual nonrespondents in the urine collection would have
tested positive for either pathogen had they been tested. These imputed
probability values for respondents who did not provide a urine specimen were
combined with the actual gonococcal and chlamydial infection test results for
respondents who did provide specimens. The synthetic estimate derived by this
imputation process (8.1% for infection with C
trachomatis and/or N gonorrhoeae)
was quite similar to the unadjusted estimate derived from tested specimens
alone (7.9%). Since imputation for nonresponse did not have a substantial
effect on the overall prevalence estimate, we used unadjusted estimates based
on complete data in our analyses.
Other Data Sources
In addition to prevalence estimates derived from LCR testing of urine
specimens, we derived alternate prevalence estimates from physician- and
laboratory-diagnosed cases of gonococcal and chlamydial infection reported to
the BCHD in 1998 (G. Olthoff, MHA, written communication, November 2, 2001).
Health Department estimates are derived from the Baltimore STD reporting system
and eliminate instances (as duplicate reports) in which infection with the same
pathogen is reported in the same individual 2 (or more) times within a 30-day
period (W. Braithwaite, BA, written communication, December 5, 2001). Reports
of infection of the same individual outside of this 30-day period are included
in the case counts.
Alternate prevalence estimates were also derived
from survey respondents' answers to questions asking whether they had ever
heard of gonorrhea and chlamydia and, if so, had they been diagnosed as having
these infections in the 12 months prior to the survey. Respondents' answers
provide 2 estimates of the prevalence of diagnosed infection. The first and
lower estimate assumes that respondents who had not heard of a disease
(gonorrhea or chlamydia) had not been diagnosed as having the disease in the
previous 12 months. A second and higher estimate assumes that persons who had
never heard of the infection were just as likely to have been diagnosed as
having this infection in the past 12 months as respondents who had heard of the
infection.
For both diagnoses reported to the BCHD and
those reported by survey respondents, we assume that diagnosis is accompanied
by treatment, although in a small but unknown number of cases this may not be
true.
RESULTS
Survey Execution
Of the 3182 households selected for interview, 2727 (85.7%) were successfully
screened. Screening identified a total of 1224 English-speaking adults who were
between the ages of 18 and 45 years and eligible for interview. Survey
interviews were completed with 1014 respondents (82.8%) between January 1997
and September 1998.
The protocol specified that only respondents
between the ages of 18 and 35 years were eligible to provide urine for
gonorrhea and chlamydia testing. Of the 1014 respondents between the ages of 18
and 45 years who completed the interview, 728 respondents aged 18 to 35 years
were asked to provide urine for testing. Of the 728 age-eligible respondents,
579 (79.5%) provided a urine specimen adequate for testing, 119 (16.3%) refused
to provide a urine specimen, and 30 (4.1%) were not tested because of
inadequate urine volume, interviewer error, or other logistical problems. Table 1
presents the unweighted numbers of adults providing urine samples and weighted
percentage distributions for selected sociodemographic groups.
Estimated Prevalence of
Untreated Infections
Among Baltimore adults aged 18 to 35 years, we estimate the prevalence of
untreated chlamydial infection is 3.0% (SE, 0.8%) and the prevalence of
untreated gonococcal infection is 5.3% (SE, 1.4%) (Table 2).
Overall, 0.4% (SE, 0.3%) of adults are estimated to have both infections (data
not shown), and 7.9% (SE, 1.6%) of Baltimore adults aged 18 to 35 years are
estimated to have either gonococcal or chlamydial infection (or both). The
difference between the estimated prevalence of these 2 infections is not
statistically significant (P =
.16). All respondents who reported a diagnosis of gonococcal (unweighted sample
of 9) or chlamydial (unweighted sample of 13) infection in the past 12 months
tested negative by LCR for the diagnosed (and presumably treated) pathogen.
Table 2
includes both weighted population prevalence estimates and unweighted counts of
the numbers of infections detected and subjects tested. The unweighted sample
counts represent the results of our NAAT analysis; they do not provide valid
estimates of the prevalence of infection in the population as a whole or in any
subpopulation. Since we used a complex sample design that purposely oversampled
certain segments of the population (see above), only the weighted estimates can
be used to make inferences about the prevalence of NAAT-detectable infections
in the population.
Impact of Assay Performance on
Estimated Prevalence
Assuming the sensitivity of the LCR assay was 0.90 to 0.94 and specificity was
0.990 to 0.999, sensitivity analysis indicates that the "true"
underlying prevalence of chlamydial infection would be 2.2% to 3.2%, given our
population prevalence estimate of 3.0%. For gonorrhea, the "true"
underlying prevalence would be 4.6% to 5.8%, given our population prevalence
estimate of 5.3%. This sensitivity analysis suggests that our prevalence
estimates are not substantially affected by the imperfection of the LCR assay.
Untreated Infections by Sex,
Race, and Age
The prevalence of gonococcal and chlamydial infections varies substantially
across subpopulations (Table 2).
We estimate that 15.0% (SE, 3.7%) of black women have gonococcal and/or
chlamydial infections while the estimated infection rates are significantly
lower for black men (6.4% [SE, 2.1%]; P
= .02) and nonblack women (1.3% [SE, 0.5%]; P<.001).
Estimated prevalence was lower among nonblack men (2.8% [SE, 1.3%]) than among
black men, although the difference was not significant. For both blacks and for
women, gonococcal infection appears to be more prevalent than chlamydial
infection, but this difference is also not statistically significant.
Table 3
shows a significant decline with age in the estimated prevalence of
NAAT-detectable chlamydial infections (P
= .006 for trend) and subjects' reports of diagnoses of gonococcal infections
during the past 12 months (P =
.02 for trend). A parallel, although less uniform and nonsignificant, trend
occurs for chlamydial infections diagnosed in the past year.
Current untreated gonococcal infections show a
different pattern. The highest prevalence of detectable gonococcal infection
(10.2% [SE, 3.3%]) occurs among persons aged 31 to 35 years. While the number
of infections detected is small (unweighted counts: 33/579 [aged 18-35 years]
and 17/207 [aged 31-35 years]), the unexpectedly high prevalence estimated for
gonococcal infection among older respondents is unlikely to be due to the small
sample sizes. (The null hypothesis that the population prevalence of gonococcal
infections is equivalent among adults aged 31 to 35 years and those aged 18 to
30 years is rejected with P<.001.)
High estimated prevalences of untreated gonococcal infections are observed
among both men (7.8%) and women (12.2%) in the group aged 31 to 35 years (data
not shown).
Symptoms and Antibiotic Use
The high prevalence of untreated infections estimated for the Baltimore
population raises questions about the reasons why medical diagnosis and
treatment were not obtained. Interview data indicate that symptoms were rarely
reported among persons with untreated gonococcal or chlamydial infections.
Excluding persons receiving treatment for a gonococcal or chlamydial infection
in the previous 6 months, only 2.0% of currently infected respondents reported
dysuria (burning on urination) and 4.7% reported discharge within the past 6
months. Untreated infections were found less frequently among persons reporting
dysuria during the preceding 6 months than among those who did not report this
symptom (prevalence: 2.0% vs 8.8% [odds ratio {OR}, 0.21]; P = .08). Similarly, infections were less
likely to be reported among persons who report dripping or discharge in the
past 6 months than among those who did not, but this difference did not
approach statistical significance (4.7% vs 8.4% [OR, 0.54]; P = .43).
Persons who reported antibiotic use in the 6
months prior to testing were less likely to test positive for gonococcal and/or
chlamydial infection than those who reported no antibiotic use in this period
(4.4% vs 10.5% [OR, 0.40]; P =
.04). In theory, variation in the use of antibiotics could produce a negative
association between symptom reporting and current infection status if
antibiotics were administered presumptively on the reporting of dysuria or
discharge. To control for this possibility, we examined the relationship of
symptoms and current infection status in persons reporting no antibiotic use
and no diagnosed gonococcal or chlamydial infections in the 6 months prior to
testing. A trend toward asymptomatic infection remains (OR, 0.24 for dysuria;
and OR, 0.32 for discharge), however, with the diminished sample sizes, these
results are not statistically significant (P
= .19 and P = .30, respectively).
Number of Treated vs Untreated
Infections
Overall, 4566 gonococcal infections were diagnosed in persons aged 18 to 35
years and reported to the BCHD in 1998 (Table 4).
This would represent a maximum population prevalence of 2.6% (under the
assumption that no person had 
2 infections recorded
during the year). Interview data provided by our survey respondents suggest
that between 4708 (2.7%) and 5231 (3.0%) individuals in this age group were
diagnosed as having (and presumably received treatment for) gonococcal
infections in the 12 months prior to our survey. Based on NAAT assays of urine
specimens, we estimate that 9241 (5.3%) of this age group had a current and
untreated gonococcal infection at the time of our survey. The divergence in
estimates of diagnosed and undiagnosed gonococcal infections is most striking
for women. Three estimates of the number of women (aged 18-35 years) diagnosed
as having gonococcal infection annually in Baltimore lie in the range of 1272
(1.4%) to 2051 (2.3%). NAAT analysis of urine specimens from our probability
sample of this population leads us to estimate that 6087 women (6.7%) were
carrying an undiagnosed gonococcal infection at the time of the survey.
For chlamydial infection, BCHD records indicate
that 3664 infections were diagnosed in this age group in 1998. This represents
a maximum prevalence of 2.1%. Responses during the survey interview suggest
that 5580 (3.2%) to 6975 (4.0%) of the population were diagnosed as having and
presumably treated for chlamydial infections in the 12 months prior to our
survey. Testing of urine specimens yields an estimate that 5231 (3.0%) of this
age group had a current and untreated chlamydial infection. Examination of the
results by sex indicates that only 391 men (0.5%) were diagnosed as having
chlamydial infections and reported to the BCHD in 1998 while our testing of
urine specimens yields an estimate that 1336 men in this age group (1.6%) had a
current untreated chlamydial infection. Male respondents reported diagnoses of
chlamydial infection by their health care providers at rates that are
considerably higher than recorded in BCHD statistics (1.9%-2.5% vs 0.5%). This
may reflect presumptive treatment (eg, for nongonococcal urethritis) without
diagnostic testing.
COMMENT
The foregoing estimates indicate that nearly 1
in 12 (7.9%) Baltimore adults between the ages of 18 and 35 years has an
untreated infection with either N
gonorrhoeae or C trachomatis.
The estimated prevalence for black women is greater than 1 in 7 (15.0%). Two
important conclusions emerge when these estimates, which represent undiagnosed
infections prevalent in the population, are compared with estimates of the
number of infections diagnosed annually. First, the combined number of
gonococcal and chlamydial infections that persist undiagnosed and untreated in
this population exceeds the number of infections that are diagnosed and treated
in a given year. Second, there appears to be a large reservoir of undiagnosed
gonococcal infections in Baltimore, particularly among women.
It is impossible to know the duration of the
infections detected in this study. We note, however, that nearly all of the
detected infections occurred among adults who reported no recent symptoms. In
addition, elevated levels of gonococcal infection were detected among older
adults aged 31 to 35 years. The lack of symptoms and high levels of gonococcal
infection among the oldest sampled age group suggest that persistent infections
may be responsible for the high prevalence of untreated asymptomatic infections
detected in this study. Longstanding infections may represent low organism
burden, partial immunological clearance,26 or infection with
organism strains that cause less symptomatic disease.27 In some cases, these
persistent asymptomatic infections may be associated with significant sequelae,
such as infertility. In other cases, the clinical importance and
transmissibility of these infections is less clear.28 Although there is
some uncertainty about the interpretation of NAAT-detected infections, we
believe our findings have 2 important implications.
First, prompt consideration should be given to
strategies for improving the diagnosis and treatment of asymptomatic infections
in this population. The urine-based NAAT assays used in this research are
approved by the Food and Drug Administration for diagnosis of gonococcal and
chlamydial infections. As such, we believe it is prudent to plan appropriate
public health actions in response to the high prevalence rates we have
detected. Strategies for reducing the prevalence of infection in this
population might include screening or routine testing in health care settings
for the entire population of young adults, including persons who formerly would
be considered to be at low risk of infection. (Such efforts will require
confronting issues that are beyond the scope of the present article, including
identification of appropriate methods for delivering and financing such
testing, and the role to be played by public health facilities and private
health care providers.)
In support of this recommendation, we note that
Mehta et al29 recently
reported testing 454 patients (aged 18-31 years) seeking medical care for
reasons other than STD symptoms at the adult emergency department at Johns
Hopkins Hospital and Health System (Baltimore, Md). Using urine-based NAAT
assays, investigators found that 9.3% of these patients tested positive for
chlamydial infection and 5.3% tested positive for gonococcal infection. Their
sample is not directly comparable with our own since they recruited patients in
a large Baltimore emergency department. However, both our estimates and those
of Mehta et al are derived from screening adult populations outside of an STD
care setting.
The second implication of our findings is that
research is urgently needed to improve our understanding of the clinical and
public health significance of NAAT-detectable infections. It is possible that
NAAT assays are identifying clinically inconsequential infections because of
the assays' ability to detect extremely low levels of viable organisms (ie,
below the infectious inoculum) or amplifiable DNA (or RNA) from residual
pathogens (ie, nonviable organisms) of past infections that are well on their
way to being cleared. One potentially informative line of research may be to
compare the transmissibility and clinical consequences of infections that are
detectable only by NAAT assay vs those that are detectable by traditional
assays.30
In addition to its substantive findings, the
present study provides an example of the feasibility and benefits of combining
population survey techniques and NAAT analysis of urine specimens in research
on the epidemiology of STDs. Such research can complement and enrich the
epidemiological insights gained from studies using case reporting systems and
studies of clinical and other special populations. Most importantly, this
research permits generalizations about the prevalence in the population at
largeor at least in that
fraction of the population who consents to being surveyed.
Interpretation of our research findings will
benefit from replication. Since teenagers both contract infections from and
transmit infections to the adult population, any replication should include
this segment of the population. Annual or biannual monitoring of STD prevalence
using population survey techniques in Baltimore and elsewhere could enrich our
understanding of the epidemiology of these STDs. It could also provide
important guidance on the appropriate roles of population prevalence data and
STD case reports in tracking trends in these STDs and identifying
subpopulations that might benefit from screening or other interventions
designed to inhibit the spread of these infections.
Author/Article Information
Author Affiliations: Program in
Health and Behavior Measurement, Research Triangle Institute, Washington, DC
(Drs Turner, Rogers, H. Miller, and Gribble); City University of New York,
Queens College and Graduate Center, Flushing, NY (Dr Turner); Statistics
Research Division (Dr Chromy) and Research Computing Division (Mr Cooley),
Research Triangle Institute, Research Triangle Park, NC; Division of Infectious
Diseases, Department of Medicine and Department of Epidemiology, University of
North Carolina, Chapel Hill (Drs W. Miller and Leone); Division of Infectious
Diseases, School of Medicine, Johns Hopkins University, Baltimore, Md (Drs
Quinn and Zenilman); National Institute of Allergy and Infectious Diseases,
Bethesda, Md (Dr Quinn).
Corresponding Author and Reprints:
Charles F. Turner, PhD, Program in Health and Behavior Measurement, Research
Triangle Institute, 1615 M St NW, Washington, DC 20036 (e-mail: [log in to unmask]).
Author Contributions: Study concept and design:
Turner, Rogers, H. Miller, Gribble, Chromy, Cooley, Quinn, Zenilman.
Acquisition of data: Turner, Rogers, H. Miller, Gribble, Chromy, Cooley, Zenilman.
Analysis and interpretation of
data: Turner, Rogers, H.
Miller, W. Miller, Chromy, Leone, Quinn, Zenilman.
Drafting of the manuscript: Turner, Rogers, W. Miller, Leone.
Critical revision of the
manuscript for important intellectual content: Turner, Rogers, H. Miller, W. Miller, Gribble, Chromy, Cooley,
Quinn, Zenilman.
Statistical expertise: Rogers, W. Miller, Chromy.
Obtained funding: Turner, H. Miller.
Administrative, technical, or
material support: Turner, Rogers, H.
Miller, Gribble, Leone, Cooley, Zenilman.
Study supervision: Turner, H. Miller.
Funding/Support: Primary support for this research was provided by NIH grant
R01-HD31067 to Dr Turner. Additional support was provided by the Research
Triangle Institute and by grant R01-MH56318 to Dr Turner, and grants
K24-AI01633 and U19-AI38533 to Dr Zenilman. Dr W. Miller received support
through the Clinical Associate Physician Program of the General Clinical
Research Center (RR00046), Division of Research Resources, National Institutes
of Health. Abbott Laboratories donated some of the LCR test kits used in this
study.
Acknowledgment: We thank Jeff Yuenger for his assistance in organizing the
laboratory testing and the survey operations staff of the Research Triangle
Institute for their fielding of the survey.
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Diplomat American
Board of Palliative Medicine.