Sexually Transmitted Disease Surveillance 1993

Division of STD/HIV Prevention 

December 1994

U.S. Department of Health and Human Services 
Public Health Service 
Centers for Disease Control and Prevention 
National Center for Prevention Services 
Division of STD/HIV Prevention 
Surveillance and Information Systems Branch 
Atlanta, Georgia 30333

                         Copyright Information 

All material contained in this report is in the public domain and may be
used and reprinted without special permission; citation to source,
however, is appreciated.

                           Suggested Citation

Division of STD/HIV Prevention. Sexually Transmitted Disease
Surveillance, 1993.  U.S. Department of Health and Human Services, Public
Health Service.  Atlanta: Centers for Disease Control and Prevention,
December 1994.

Copies can be obtained from Information Services, National Center for
Prevention Services, Centers for Disease Control and Prevention, 1600
Clifton Road, Mailstop E-06, Atlanta, Georgia 30333.

                     
                     Sources and Limitations of Data 

CDC Surveillance Data

     The information in this document was based on cases of sexually
transmitted diseases (STDs) reported to the Division of STD/HIV Prevention
(DSTD/HIVP), Centers for Disease Control and Prevention (CDC), by the STD
control programs and health departments in the 50 states, the District of
Columbia, selected cities, and U.S. dependencies and possessions, and
independent nations in free association with the United States.*  Data were
received as summary statistics monthly, quarterly, and annually.  Monthly
reports included summary data for syphilis by county and state.  Quarterly
reports included summary data for syphilis, gonorrhea, and other STDs by
gender and source of report (public, private, or military) for the 50
states, 64 large cities (most with a population of 200,000), and outlying
areas of the United States.  Annual reports included summary data for
syphilis and gonorrhea by age, race, and gender for the 50 states and six
large cities.  In addition, data on antimicrobial susceptibility in
Neisseria gonorrhoeae were collected through the Gonococcal Isolate
Surveillance Project (GISP), a sentinel system of 27 STD clinics and 5
laboratories located throughout the U.S.  Provisional data on syphilis and
gonorrhea reported to CDC weekly by states for inclusion in the Morbidity
and Mortality Weekly Report were not included in this document.

     Areas differ in their ability to resolve differences in total cases
derived from monthly, quarterly, and annual reports.  Thus, depending on
the database used, there may be discrepancies in total cases in the tables
and figures.  In most instances, these discrepancies are less than 5% of
total reported cases and have minimal impact on national total cases and
rates.  However, for a specific area, the discrepancies may be larger.
     
     Reports and corrections sent to CDC through February 28, 1994, have
been included.  Those received after this date will appear in subsequent
issues.  The data in the tables and figures in this document supersede
those in all earlier publications.

Population Denominators and Rate Calculations

     Incidence rates were calculated on an annual basis per 100,000
population.  For the United States, rates were calculated by using Bureau
of the Census population estimates for 1981 through 1989 (Bureau of the
Census;  United States Population Estimates by Age, Sex and Race: 1980-1989 
[Series P-25, No. 1045]; Washington: US Government Printing Office, 1990;
and United States Population Estimates by Age, Sex and Race: 1989  [Series
P-25, No. 1057]; Washington: US Government Printing Office, 1990).  Rates
for states and counties were calculated by using published intercensal
estimates based on Bureau of the Census population estimates for 1980-1989
(Irwin R; 1980-1989 Intercensal Population Estimates by Race, Sex, and Age; 
Alexandria, [VA]: Demo-Detail, 1992; machine-readable data file).   Rates
for 1990 were calculated using population data from the 1990 census (Census
of Population and Housing, 1990: Summary Tape File 1 (All States)
[machine-readable file]; Washington: Bureau of the Census, 1991), which
included information on area (county, state), age (5-year age groups), race
(white, black, Asian/Pacific Islander, American Indian/Alaskan Native) and
ethnicity (Hispanic).  Rates for 1991-1992 were updated from previous
issues of this report using postcensal population estimates for 1991-1992
based on the Bureau of the Census data (Irwin R; 1991-1992 Postcensal
Population Estimates by Race, Sex, and Age;  Alexandria, [VA]: Demo-Detail,
1994; machine-readable data file).  Rates for 1993 were calculated using
the postcensal 1992 population denominators cited previously.

     Many cities do not have a separate health jurisdiction that collects
and reports cases of STD.  For these cities, case numbers and incidence
rates are equal to those of the county or counties in which the city is
located.  For the remaining cities, incidence rates were calculated by
using population estimates based on the Bureau of the Census (Irwin R, see
above) and a marketing survey (Market Statistics, Inc; Sales and Marketing
Management; New York: Bill Communications, Inc, August 1989).  Population
estimates for areas outside the United States were obtained from the Bureau
of the Census (Bureau of the Census; population estimates for Puerto Rico
and the outlying areas: 1980 to 1988; Current Population Reports [Series
P-25, No. 1049]; Washington: US Government Printing Office, 1989). 
Population estimates for the outlying areas for 1989-1991 were obtained
directly from the health departments in these areas.  Rates in these areas
for 1992-1993 used 1991 population estimates.

     The percentage of cases for which race/ethnicity and age were unknown
or unspecified differed considerably, depending on year and area.  In 1983
and 1984, up to 25% of total U.S. cases were in this category.  In these
years, states were excluded from analysis if race/ethnicity and age were
not reported for the majority of cases.  Otherwise, if race/ethnicity or
age was unknown or unspecified, cases were distributed according to the
cases for which these data were available.

     Rates of congenital syphilis were calculated using live births from
the National Center for Health Statistics (NCHS)(Vital Statistics: Natality
Tapes, 1989-1991).  Rates before 1989 were calculated using published live
birth data (NCHS; Vital Statistics Report, United States, 1988[Vol.
1--Natality]).

Case Definitions and Reporting Practices

     Although most areas generally adhere to the case definitions for STD
found in Case Definitions for Public Health Surveillance (MMWR
1990;39(RR-13):1-43), there are significant differences between individual
areas in case definitions as well as in the policies and systems for
collecting surveillance data.  Thus, comparisons of case numbers and rates
between areas should be interpreted with caution.  However, since case
definitions and surveillance activities within a given area remain
relatively stable, trends should be minimally affected.  In many areas,
reporting from publicly supported institutions (e.g., STD clinics) was more
complete than from other sources (e.g., private practioners).  Thus, the
trends may not be representative of all segments of the population. 
Military cases are not reported as a separate category.

     In 1989, a new surveillance case definition for congenital syphilis
was introduced.  The new case definition has greater sensitivity than the
former definition.  In addition, many areas greatly enhanced active case
finding for congenital syphilis during this time.  For these reasons, the
number of reported cases increased dramatically during 1989-1991.  As is
true of any change, a period of transition during which trends cannot be
clearly interpreted has resulted; however, all reporting areas had
implemented the new case definition for reporting all cases of congenital
after January 1, 1992.  Therefore, the reliability of trends is expected to
stabilize for data reported after this date.

Reporting of Chlamydia Cases

     Some areas do not yet have laws or policies for uniform reporting of
Chlamydia trachomatis cases, and their reported cases and rates are much
lower than expected or zero.  Population denominators from these areas are
excluded when calculating U.S. total rates.  Trends in many areas are more
representative of increases in reporting of cases rather than actual trends
in disease.  Despite the problems with underreporting, we feel it is
important to publish the data to emphasize the large numbers of cases of
chlamydia being detected in the United States.  As areas develop chlamydia
prevention and control programs, including improved surveillance systems to
monitor trends, the data should improve and become more representative of
true trends in disease.

     Chlamydia testing data for the area-specific figures in the Special
Focus Profiles section were published with permission from the following: 
the Region X Chlamydia Project; the San Francisco Department of Public
Health; the Ohio Department of Health; and the Wisconsin State Laboratory
of Hygiene.

Other Data Sources

     The information on the number of initial visits to private
practioners' offices for sexually transmitted diseases was based on
analysis of data from the National Disease and Therapeutic Index
(machine-readable files for years 1966-1993).  For more information on this
database, see IMS America, Ltd; National Disease and Therapeutic Index
(NDTI): Diagnosis April 1989-March 1990; Plymouth Meeting (PA): IMS
America, Ltd, 1990.

     The information on patients hospitalized for pelvic inflammatory
disease or ectopic pregnancy was based on analysis of data from the
National Hospital Discharge Survey (machine-readable files for years
1980-1992), an ongoing nationwide sample survey of short-stay hospitals in
the United States, conducted by the National Center for Health Statistics. 
For more information, see Graves EJ; 1988 Summary: National Hospital
Discharge Survey; Advance data No. 185; Hyattsville (MD): National Center
for Health Statistics, 1990.


*Included among the dependencies, possessions, and independent nations are
Guam, Puerto Rico, and the Virgin Islands.  These are referred to as
"outlying areas of the U.S." in the tables.
           

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