Trends in the use of sexually transmitted disease diagnostic technologies in California, 1996-2003.
ABSTRACT To describe trends in STD diagnostic test volume and test technology in California from 1996 to 2003.
A self-administered survey was mailed annually to licensed clinical laboratories in California that performed STD testing. Data were collected on volume and diagnostic test type for chlamydia, gonorrhea, syphilis, chancroid, HIV, hepatitis B, herpes simplex virus (HSV), and human papilloma virus (HPV). Data were analyzed for trends over time.
Response rates ranged from 77% to 99% per survey year. The total number of chlamydia, gonorrhea, and syphilis tests increased from 8.1 to 9.3 million annually. The proportion of chlamydia and gonorrhea tests performed using nucleic acid amplification testing increased from 5% to 66% and from 1% to 59%, respectively. Gonorrhea culture testing decreased from 42% to 10% of all gonorrhea tests. HIV test volume increased from 2.4 to 3.1 million tests. Newer technology tests for HSV and HPV were less common but increased in use. Non-public health laboratories conducted over 90% of all STD testing.
Analyzing trends in diagnostic technologies enhances our understanding of the epidemiology of STDs and monitoring laboratory capacity and practices facilitates implementation of STD control activities.
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ABSTRACT: We analyzed 265 urethral Neisseria gonorrhoeae specimens collected from symptomatic males at San Francisco's municipal sexually transmitted disease clinic, a participant in the Gonococcal Isolate Surveillance Project, during 2009. We used N. gonorrhoeae multiantigen sequence typing to describe characteristics of patients infected with common sequence type families. Specimens were classified into 6 homology-based families and 1 additional family of all other identified strains. Strain family results were combined with results of culture-based antibiotic sensitivity minimum inhibitory concentration, sociodemographic and behavioral risk data collected at the clinic, and presence or absence of the mosaic penicillin-binding protein 2 (penA) allele. Characteristics of patients were compared across strain families through the use of χ(2) statistics. Among men who have sex with men, strain distribution differed by those reporting receptive oral sex as their only urethral exposure (P = 0.04), by number of sex partners (P = 0.03), and by race/ethnicity (P < 0.001); there were no differences by age or human immunodeficiency virus status. Also, among men who have sex with men, strain family distributions differed for culture specimens with reduced susceptibility to a range of antibiotics, as well as with presence of the mosaic penA allele (all P < 0.001). The combination of molecular, phenotypic, and epidemiologic data on N. gonorrhoeae infection could help develop a more complete epidemiology of gonorrhea in the United States.American journal of epidemiology 09/2013; · 4.98 Impact Factor
- Sexually transmitted diseases 08/2009; 36(7):419-21. · 2.58 Impact Factor
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ABSTRACT: Sexual transmitted infections (STIs) have increased in Germany and other countries in Europe since the mid-nineties. To obtain a better picture of diagnostic methods used in STI testing institutions in Germany, we performed a nationwide survey amongst STI specialists in order to evaluate the quality of STI reports and provide recommendations to harmonize and possibly improve STI diagnostics in Germany. We asked sentinel physicians and randomly chosen gynaecologists, urologists and dermato-venerologists, about the diagnostic methods used in 2005 to diagnose HIV, chlamydia (CT), gonorrhoea (GO) and syphilis (SY) in a national cross-sectional survey in order to recognize potential problems and provide recommendations. A total of 739/2287 (32%) physicians participated. Of all participants, 80% offered tests for HIV, 84% for CT, 83% for GO and 83% for SY. Of all participants who performed HIV testing, 90% requested an antibody test, 3% a rapid test and 1% a nucleic acid amplification test (NAAT). For CT testing, NAAT was used in 33% and rapid tests in 34% of participants. GO resistance testing was performed by 31% of the participants. SY testing was performed in 98% by serology. Diagnostic methods for STI vary highly among the participants. Diagnostic guidelines should be reviewed and harmonised to ensure consistent use of the optimal STI diagnostic methods.BMC Infectious Diseases 01/2010; 10:98. · 2.56 Impact Factor
Trends in the Use of Sexually Transmitted Disease Diagnostic
Technologies in California, 1996–2003
KATHERINE AHRENS, MPH,* K. JAYNE BRADBURY, MPH,* HEIDI M. BAUER, MD, MPH,*
MICHAEL C. SAMUEL, DRPH,* GAIL GOULD,* GIANNINA DONATONI, PHD,† CHANDRA HIGGINS, MPH,†
PETER KERNDT, MD, MPH,† AND GAIL BOLAN, MD, MPH*
Objective: To describe trends in STD diagnostic test volume and
test technology in California from 1996 to 2003.
Study: A self-administered survey was mailed annually to licensed
clinical laboratories in California that performed STD testing. Data
were collected on volume and diagnostic test type for chlamydia,
gonorrhea, syphilis, chancroid, HIV, hepatitis B, herpes simplex virus
(HSV), and human papilloma virus (HPV). Data were analyzed for
trends over time.
Results: Response rates ranged from 77% to 99% per survey year.
The total number of chlamydia, gonorrhea, and syphilis tests increased
from 8.1 to 9.3 million annually. The proportion of chlamydia and
gonorrhea tests performed using nucleic acid amplification testing
increased from 5% to 66% and from 1% to 59%, respectively. Gon-
orrhea culture testing decreased from 42% to 10% of all gonorrhea
tests. HIV test volume increased from 2.4 to 3.1 million tests. Newer
technology tests for HSV and HPV were less common but increased in
use. Nonpublic health laboratories conducted over 90% of all STD
Conclusions: Analyzing trends in diagnostic technologies enhances
our understanding of the epidemiology of STDs and monitoring lab-
oratory capacity and practices facilitates implementation of STD con-
Diagnostic testing is an essential component of successful sexually
transmitted disease (STD) control programs as it ensures definitive
diagnosis in symptomatic patients and facilitates screening in
asymptomatic individuals. Clinical laboratories are the cornerstone
of public health efforts to effectively identify STDs and conduct
disease surveillance. Although California regulations require both
health care providers and laboratories to report persons testing
positive for selected STDs, the majority of disease reports are
initially received from laboratories.1,2In addition, laboratory tech-
nicians have expertise in test technologies, interpretation of results,
and use and limitations of specific test types, therefore playing an
important role in educating clinicians about diagnostic quality
assurance and performance issues.
Monitoring levels of testing, laboratory practices, and trends in
the use of technology enhances STD control efforts by improving
the interpretation of STD trends, creating valuable partnerships
with laboratories, facilitating the evaluation of screening pro-
grams, and investigating outbreaks.3–5The increase in use of more
sensitive tests for chlamydia screening and diagnosis provided a
partial explanation for local and national increases in chlamydia
incidence.6Further, partnerships with laboratories and electronic
data transmission have enabled broad-based prevalence monitor-
ing at family planning clinics.7Documenting trends in STD test
volume and the use of superior diagnostic tests enables the eval-
uation of compliance with current STD test recommendations.8,9
In addition, these data aid in the examination of aberrations in
disease detection that may result from an increase in false positives
caused by a loss of test specificity or cross-contamination. Know-
ing laboratory capacity to perform culture and susceptibility test-
ing is essential for investigating treatment failures and suspected
outbreaks of drug-resistant gonorrhea.
In 1985, the Centers for Disease Control and Prevention (CDC)
first recommended routine collection of laboratory testing infor-
mation as part of STD surveillance activities.10In 2002, the CDC
updated this recommendation, and provided the California survey
instrument as a template.11Key findings from the California An-
nual Clinical Laboratory Survey from 1996 to 2003 are described
Respondents and Recruitment
The California Annual Clinical Laboratory Survey is a cross-
sectional, self-administered survey of laboratory services and prac-
The authors are indebted to the California laboratory directors who have
participated in the California Annual Clinical Laboratory Survey. The
authors also thank the following staff from California Department of
Health Services STD Control Branch: Berlene Osafo-Mensah and Denise
Gilson for data entry and management, Abby Sokoloff and Mi-Suk Kang
for report generation, the Disease Investigation Area Managers for fol-
low-up activities, Jessica Frasure for editing and formatting, and Roger
Tulloch and Jean Montes for survey instrument development. We also
thank the following staff from Los Angeles STD Control Program: Clarice
Gillis for managing data collection and follow-up activities, Irene Dyer for
overseeing the survey from 1995 to 2000, and Merril Marty for develop-
ment of the original questionnaire.
This project was supported in part by the Centers for Disease Control
and Prevention (Comprehensive STD Prevention Systems and Infertility
Prevention Project Grant H25/CCH904362), the California Department of
Health Services, and the Los Angeles STD Control Program.
Correspondence: K. Jayne Bradbury, California Department of Health
Services, STD Control Branch, 850 Marina Bay Parkway, Building P, 2nd
floor, Richmond, CA 94804. E-mail: email@example.com.
Received for publication August 22, 2006, and accepted October 27,
From the *California Department of Health Services STD Control
Branch; and †Los Angeles Department of Health Services STD
Sexually Transmitted Diseases, July 2007, Vol. 34, No. 7, p.513–518
Copyright © 2007, American Sexually Transmitted Diseases Association
All rights reserved.
tices among licensed clinical laboratories in California that re-
ported performing STD tests. The California Department of Health
Services STD Control Branch (CA STD) and Los Angeles County
(LAC) Department of Health Services STD Program (LA STD)
have jointly administered the survey since 1996. That year, sur-
veys were mailed to the laboratory directors of all laboratories
licensed with the California Department of Health Services Lab-
oratory Field Services. In subsequent years through 2002, except
1998 when the CA STD did not implement the annual survey, CA
STD surveyed all California laboratories (excluding LAC labora-
tories) that reported STD testing in the previous year. In addition,
all laboratories for which no STD testing information was known
from previous years as well as newly licensed laboratories were
surveyed each year. In 2003, CA STD resurveyed all licensed
laboratories in California (excluding LAC laboratories) to include
laboratories that may have started conducting STD testing. For all
survey years, 1996 through 2003, LA STD surveyed laboratories
in LAC that performed STD testing, as determined by contacting
all licensed laboratories in LAC or through collaboration with a
knowledgeable local laboratory consultant. Survey participation
was voluntary and no incentives were offered. Because the survey
was considered a component of routine public health assessment
activities, formal human subjects research review was not sought.
Only data collected by both CA STD and LA STD in the years
1996 through 2003 were included in the analysis.
Procedures for follow-up varied by year and by survey admin-
istrator. In general, for laboratories outside of LAC, nonrespon-
dents received up to three telephone calls and a site visit. In 2002,
staff shortages necessitated only minimal follow-up efforts, with
nonrespondents receiving between zero and two phone calls. In
2003, nonrespondents received up to eight telephone calls but no
site visits. For all survey years, nonrespondents in LAC received
telephone calls and site visit follow-up.
Data Collection and Test Technologies
CA STD and LA STD jointly designed the survey instruments
based on an original template developed by LA STD. The instru-
ment included questions on the volume and types of tests for
chlamydia, gonorrhea, syphilis, chancroid, human immunodefi-
ciency virus (HIV), hepatitis B, herpes simplex virus (HSV), and
human papillomavirus (HPV); other laboratory practices including
gray zone analyses and verification testing for chlamydia and
antibiotic resistance testing for gonorrhea were assessed. The
survey did not distinguish between tests that were conducted on
specimens from within the state of California and those that were
conducted on out-of-state specimens. Test types were added or
deleted throughout the survey years in response to changes in the
availability and introduction of new FDA-cleared test technolo-
gies. Open-ended questions were included for all diseases to allow
respondents to indicate their use of technologies not specifically
listed on the survey.
Data were collected on the following chlamydia test types: culture,
direct fluorescent antibody (DFA), enzyme immunoassay (EIA),
DNA probe assays (Gen-Probe PACE? 2, Digene Hybrid Capture?
II), nucleic acid amplification tests (NAATs) (Abbott Laboratories
LCx?, Roche Amplicor?, Gen-Probe AmpCT/APTIMA?, and Bec-
ton-Dickinson BDProbeTec? ET). Data on verification practices for
positive EIA and DNA probe tests were collected since 1997; con-
firmation and repeat testing of chlamydia results in the gray zone was
also assessed since 2000. Data collected on gonorrhea test types
included Gram stain, culture, DNA probe (as above), and NAATs (as
above). Data on ?-lactamase testing at laboratories performing gon-
orrhea cultures were collected since 2001.
Data collected on syphilis test types included nontreponemal se-
rology tests (rapid plasma reagin (RPR) and Venereal Disease Re-
search Laboratory (VDRL)), treponemal serology tests (fluorescent
treponemal antibody absorption (FTA-Abs), Treponema pallidum
particle agglutination (TP-PA), microhemagglutination assay Trepo-
nema pallidum (MHA-TP), and Captia Syphilis-G? EIA), darkfield,
and direct fluorescent antibody Treponema pallidum (DFA-TP). The
survey distinguished between qualitative nontreponemal serology
tests, generally used for screening, and quantitative nontreponemal
serology tests generally used to assess titer level and response to
treatment. Starting in 1997, data on laboratory practices of ruling out
prozone reaction or diluting “rough” RPR positive tests were col-
lected. Chancroid tests included culture.
Data were collected on the following HIV test types: serum EIA,
oral EIA, urine EIA, qualitative polymerase chain reaction (PCR),
Western Blot, and immunofluorescent assays (IFA). Related tests
included viral load testing and CD4 counts. Hepatitis B tests
included surface antigen serology tests only. Data collected on
HSV test types included culture, IFA, DFA, HSV-2 type-specific
IgG and IgM serology tests (Focus Technologies HerpSelect?),
HSV nontype-specific serology tests, and unspecified serology
tests. Data collected on HPV tests included hybrid capture DNA
assays (Digene Hybrid Capture System? and Digene Hybrid Cap-
Data were also collected on laboratory facility type. Categories
included free-standing private, health maintenance organization,
blood bank, public health, nonprofit hospital, private hospital, and
Response rates were calculated for each year by dividing the
number of laboratories that responded and reported STD testing by
the number of laboratories that were considered eligible or poten-
tially eligible. Eligible laboratories included those known to per-
form STD testing; potentially eligible laboratories included those
with unknown STD testing status. Laboratories that responded to
the survey but did not perform STD tests were considered ineli-
gible. Discrepancies and anomalous test volumes were investi-
gated via telephone follow-up and appropriate corrections were
made to the data. For the years in which LA STD and CA STD
surveys were not identical, tests listed as other were recoded to
reflect consensus categories.
The volume of tests performed for each STD was summed by test
technology and then compared between years. Similar test technolo-
gies were grouped together for analysis: NAATs for chlamydia and
gonorrhea, syphilis nontreponemal serology tests, HSV-2 type-spe-
cific serology tests, and HIV EIA tests. CD4 counts and HIV viral
load tests were analyzed separately because they are primarily used
nontreponemal serology tests were also excluded from this anal-
ysis because it was impossible to distinguish those that were being
used for diagnostic testing and those being used to assess titer level
and response to treatment. Test volume and practices were sum-
marized and compared by facility type over time. For select
analyses, trends were assessed specifically among public health
laboratories. Data were analyzed using SAS statistical software
(SAS Institute, version 9.1, Cary, NC).
The response rate by year ranged from 77% to 99% (Table 1).
Response rates for LAC laboratories were higher than the rest of
California (average 97.3% vs. 88.9%). From 1996 to 2003, the
total number laboratories in California that conducted STD testing
Sexually Transmitted Diseases ● July 2007
AHRENS ET AL.
decreased 31% from 734 to 508, whereas the total number of
reported chlamydia, gonorrhea, and syphilis tests increased from
8.1 million to 9.3 million (Table 1). From 2002 to 2003, there was
only a 4% increase in test volume even though the response rate
increased from 77% to 92% and the number of laboratories re-
porting testing increased from 384 to 508 between these years.
Chlamydia, gonorrhea, syphilis, HIV, and hepatitis B each ac-
counted for approximately 20% of all STD tests each year since
1999; HSV and HPV accounted for 0.1% to 3.0% of STD tests.
The majority of STD testing was conducted in a relatively small
number of private laboratories. In 2003, nonpublic health labora-
tories conducted 92.9% of all STD tests combined. Between 1996
and 2003, free-standing private laboratories (a subset of private
laboratories) accounted for increasing proportions of total STD
testing (40.9% in 1996 to 47.8% in 2003). In contrast, public
health laboratories conducted only 7.1% to 10.4% of all STD
testing over the survey years. From 1996 to 2003, the high-volume
laboratories conducted an increasing majority of tests. The pro-
portion of all STD tests reported by the 50 largest laboratories
increased from 70.1% to 79.8% from 1996 to 2003. Further, the
proportion of STD tests reported by the 10 largest laboratories
increased from 42% to 48% over the same time period.
The number of chlamydia tests increased steadily over the years
surveyed from 2.2 million in 1996 to nearly 3.0 million in 2003
(Fig. 1). Since the introduction of NAATs in the mid-1990s, the
use of this technology increased from 4.9% of all chlamydia tests
in 1996 to 66.3% in 2003. Among public health laboratories,
NAATs use increased from 29.4% to 98.5% over this same time
period. DNA probe testing decreased from a high of 61.0% of tests
in 1999 to 30.4% in 2003. The use of EIA, DFA, and other less
sensitive technologies decreased steadily from 33.8% in 1996 to
1.6% in 2003. Culture accounted for less than 5% of chlamydia
tests each survey year. Among the laboratories performing EIA
tests for chlamydia, the percentage that reported EIA verification
ranged widely from 3.3% to 45.2%, with no apparent trend over
time. Among laboratories performing DNA probe testing, the
percentage reporting DNA probe verification decreased from
44.0% in 1997 to 13.9% in 2003. Additionally, of the laboratories
that reported DNA probe testing, most reported confirming or
repeating test results that were in the gray zone, ranging from
90.2% in 1999 to 76.6% in 2002; however, of these laboratories,
only a minority reported using a different test to confirm findings
in the gray zone, ranging from 18.4% in 2002 to 26.1% in 2000.
There was no apparent trend over time.
The number of gonorrhea tests increased from 2.1 million in
1996 to 3.0 million in 2003 (Fig. 2) mirroring the trend for
chlamydia testing. Gonorrhea test technologies shifted during this
period; the use of culture decreased from 42.3% of all gonorrhea
tests in 1996 to 10.3% in 2003 while NAATs increased from 0.6%
to 59.0%. Among public health laboratories, NAATs use increased
from 1.7% to 85.0% over this same time period. DNA probe
testing decreased from a peak in 1999 of 59.7% to 28.8% in 2003.
From 1996 to 2003, the proportion of laboratories reporting culture
testing decreased from 69.8% to 58.5% overall and from 81.8% to
60.5% in public health laboratories. Over half (59.3%) of labora-
Survey Year, California Annual Clinical Laboratory Survey, 1996–2003
Number of Laboratories, Survey Response Rate, Total Test Volume, and Volume and Percent of Tests for Individual STDs by
1996 199719992000 200120022003
734671 574509447384 508
97.6%98.5% 93.6% 92.9%90.7%76.5% 92.4%
10,754,42613,296,456 14,739,24315,157,19615,881,457 15,390,60916,012,482
n (%)n (%) n (%)n (%) n (%)n (%)n (%)
* Response rate calculated using the number of laboratories reporting STD testing divided by the number of eligible laboratories.
†Syphilis tests do not include VDRL and RPR quantitative titers.
‡HIV tests do not include viral load or CD4 count testing.
§HSV tests do not include HSV-1 specific test types.
Fig. 1. Total number of chlamydia tests performed and proportion
of chlamydia test types, CA, 1996–2003. DFA: direct fluorescent
antibody; EIA, enzyme immunoassay; Other includes point of care
tests and unspecified test types; NAATs: nucleic acid amplification
Vol. 34●No. 7
STD DIAGNOSTIC TECHNOLOGIES IN CALIFORNIA
tories that performed gonorrhea culture reported ?-lactamase test-
ing in 2003.
The number of syphilis tests decreased from nearly 3.8 million
in 1996 to approximately 3.3 million tests each year since 1999
(Table 1). Nontreponemal tests comprised the majority of syphilis
tests, accounting for 81.7% to 92.3% of total syphilis tests each
year, with no apparent trend. The proportion of laboratories that
performed nontreponemal tests in 1997–2003 that reported dilut-
ing out inconclusive, or rough, negative tests to rule out prozone
reactions varied by year: 48.2% in 1997 to a peak of 64.7% in 2001
to only 45.3% in 2003.
With the exception of 1997, fewer than 300 chancroid tests were
reported each year (Table 1). All chancroid tests performed were
The number of HIV tests increased from 2.4 million in 1996 to 3.1
1999 (Table 1). The majority of these tests were serum EIA tests.
Hepatitis B surface antigen test volume was relatively constant at
approximately 2.6 to 2.8 million tests each year.
The number of HSV tests generally increased over the survey
years (Table 1). Direct antigen and culture testing both decreased
between 1997 and 2003 (61.5% to 32.3% and 12.4% to 4.1%,
respectively). Concurrently, serological testing increased from
35.3% of tests in 1996 to 63.5% of tests in 2003. From 1999 to
2002 the majority (62.0–92.7%) of serological tests were HSV-2
type specific; however, in 2003 less than half (46.3%) of serologic
tests were type-specific. Removing an anomalous laboratory in
2003, raised the type-specific test proportion to 82%. The number
of HPV tests also increased over the survey years. Over 99.8% of
HPV tests in 2003 were Hybrid Capture II DNA assays.
Analysis of the California Annual Clinical Laboratory Survey
data demonstrated that STD testing, particularly chlamydia, gon-
orrhea, and HIV, increased in California between 1997 and 2003;
testing was increasingly concentrated in high volume laboratories;
private laboratories conducted the majority of STD testing; and
laboratories shifted away from culture and nonamplified tests in
favor of NAATs for chlamydia and gonorrhea testing. Test volume
trends demonstrated decreased syphilis testing, level hepatitis B
testing, and infrequent but increasing HSV and HPV testing.
Verification testing for chlamydia EIA and DNA probe assays was
not widespread while unnecessary ?-lactamase testing of gono-
coccal isolates was common. Gray zone testing declined slightly
between 2000 and 2003, however repeat gray zone testing re-
Close collaborations with laboratories are essential as we ad-
vance electronic reporting of case data and prevalence monitoring
projects. Between 1996 and 2003, the number of laboratories that
conducted STD testing dropped by nearly a third, while the overall
reported volume of STD testing increased. This consolidation of
laboratories may pave the way for more efficient communication
between health departments and laboratories since 80% of STD
testing is conducted in the 50 highest volume laboratories. Further,
the majority of testing was conducted by private laboratories. The
shift towards commercial laboratories emphasized the importance
of establishing linkages between health departments and nonpublic
health laboratories to optimize laboratory technologies and prac-
tices. This finding also underscores the limitations of the recent
national public health laboratory survey, at least in its applicability
to STD testing in California.5While we found public health
laboratories to report adopting new testing technologies at a
greater frequency than private laboratories, further comparison of
public versus private laboratories is needed.
The increase in chlamydia and gonorrhea testing in California
likely reflected increases in screening, particularly in response to
managed care efforts to improve the Health Plan Employer Data
and Information Set (HEDIS) measure established in 1999 for
chlamydia screening of sexually active women 15–25 years of
age.12The parallel increases in gonorrhea testing likely resulted
from the availability of combined chlamydia and gonorrhea tests.
Because of their superior sensitivity, NAATs are recommended for
chlamydia screening8and our data demonstrated that NAATs have
been widely implemented. NAATs are approved for noninvasive
specimens such as urine and vaginal swabs as well as endocervical
and urethral swabs, which facilitates screening in asymptomatic
men and screening in nonclinical settings.13This expanded screen-
ing combined with the enhanced diagnostic sensitivity may partly
explain the increase in chlamydia incidence in California. Multiple
factors led to the increase in NAAT use, including promotion by
the California Chlamydia Action Coalition.14Despite recommen-
dations by the National Chlamydia Laboratory Committee,15our
data showed no increase in EIA verification over time, a decrease
in DNA probe verification of positive results, and a consistently
small percentage of laboratories that reported confirming test re-
sults in the gray zone with a different test type. Lack of verification
testing further compromises the performance of these nonampli-
fied chlamydia tests.
The decline in the use of culture-based diagnostic testing for
gonorrhea may significantly hinder the ability of laboratories in
California to monitor antimicrobial susceptibilities to recom-
mended treatments. This observation has been documented in
other local and national laboratories surveys.4,5Resistance moni-
toring in California is particularly important due to widespread
fluoroquinolone resistant strains that limit gonorrhea treatment
options.16–18Recent developments in nucleic acid based technol-
ogy that allow for nonculture based antimicrobial resistance testing
may provide alternatives to culture.19Despite surveillance data
showing that penicillin-resistant gonorrhea is endemic in the
United States and California,20over half of laboratories perform-
ing gonorrhea cultures reported ?-lactamase testing of isolates.
Our finding that syphilis, HIV, and hepatitis B testing accounted
for nearly two thirds of STD testing each year was likely related to
routine screening (e.g., blood banking, prenatal care, and military
in-take). Reasons for the decrease in syphilis test volume between
Fig. 2. Total number of gonorrhea tests performed and proportion
of gonorrhea test types, CA, 1996–2003. Other includes Gram stain,
point of care tests and unspecified test types; NAATs: nucleic acid
Sexually Transmitted Diseases ● July 2007
AHRENS ET AL.
1996 and 1999 are unclear; however, they may be partly related to
declines in survey response rate. Although there was an increase in
syphilis among men who have sex with men (MSM) in California
starting in 2000,21,22an increase in screening was not discernible
from the survey data. Interpretation of syphilis testing trends is
limited by the exclusion of quantitative nontreponemal serology
tests from this analysis. Despite CDC recommendations to dilute
rough nontreponemal syphilis tests to detect a positive result when
blocking antibody obscures accurate reading,11over half of labo-
ratories neglected this practice.
After the observed increase in 1999, HIV test volume remained
relatively constant over the years surveyed. The reasons for the rise
in HIV testing seen in 1999 are unclear and may be a survey
artifact. With recent CDC recommendations to incorporate univer-
sal HIV testing into routine medical practice, future increases in
HIV testing are expected.23
The introduction of HSV-2 type-specific serology in 1999 im-
proved diagnosis of genital herpes and facilitated screening of
at-risk asymptomatic individuals. Although the majority of sero-
logical tests in California from 1996 through 2002 were HSV-2
type specific, less than half of serologic tests in 2003 were type-
specific tests. This finding should be interpreted with caution
because HSV test survey questions changed substantially from
2001 to 2003. Further, because of the relatively small volume of
HSV testing and recent release of HSV-2 serology testing recom-
mendations,24,25definitive conclusions regarding trends in HSV
serology testing in California are difficult to make. Regardless,
HSV serology tests that do not distinguish between HSV-1 and
HSV-2 have limited clinical value.26
The increase in HPV testing was largely attributable to the
introduction of HPV DNA tests in 2000. Because cytopathology
laboratories were not specifically recruited and may not have
considered themselves to be conducting STD testing, the reported
HPV test volumes may underestimate actual rates. HPV testing is
likely to continue to increase with expanding use of liquid-based
cytology and reflex testing for atypical squamous cells of unde-
termined significance (ASC-US) and adjunct screening in women
age 30 and older.27,28
This survey had several important limitations. Laboratories out-
side of LAC that reported no STD testing in 1996 or in any
subsequent year were not surveyed again until 2003, which may
have resulted in an underestimate of testing. Our resurvey of all
licensed clinical laboratories in 2003, which resulted in an increase
in the number of laboratories by 31% but a concurrent increase in
STD volume of only 4%, alleviated concerns related to potential
missed test volume for 1997–2002. The voluntary nature of the
survey along with fluctuations in response rate and changes in
participation over time may have resulted in inconsistencies in the
summary data. Because data were self-reported and generally not
validated using a second source, recording errors and estimates
may have resulted in inaccuracies in the summary data. Exclusion
of quantitative nontreponemal serology tests from the analysis may
have limited the interpretability of syphilis testing trends, as it is
possible that some of these tests may have been used for diagnostic
purposes. Finally, the survey instrument was not designed to
distinguish between tests performed on instate versus out-of-state
specimens, limiting the applicability of these results to interpret
California STD surveillance data.
The assessment of STD diagnostic testing facilitates the devel-
opment and evaluation of laboratory-based interventions as well as
programs to promote STD screening. Further, documenting trends
in diagnostic technologies enhances our understanding of the ep-
idemiology of STDs and monitoring laboratory capacity and prac-
tices facilitates implementation of STD control activities.
1. Sexually Transmitted Disease Program, Los Angeles County Depart-
ment of Health Services. Sexually Transmitted Disease Testing in
Los Angeles County: Clinical Laboratory Survey Report, 2003.
Available at: http://www.lapublichealth.org/std/lab_report_2003v2.
pdf. Accessed January 23, 2007.
2. Sexually Transmitted Disease Control Branch, California Department of
Health Services. Sexually Transmitted Disease Testing in California: 2003
Annual Clinical Laboratory Survey Summary. 2006. Available at http://
www.dhs.std.ca.gov. Accessed January 23, 2007.
3. Battle TJ, Golden MR, Suchland KL, et al. Evaluation of laboratory
testing methods for Chlamydia trachomatis infection in the era of
nucleic acid amplification. J Clin Microbiol 2001;39:2924–2927.
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