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Los Angeles County STD Surveillance Data Surveillance, Sources, Methods and Issues. Lisa V. Smith, MS, DrPH Director, Epidemiology Unit Los Angeles County Sexually Transmitted Disease Program. Overview. What are active and passive surveillance? Which STDs are reportable?
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Los Angeles County STD SurveillanceData Surveillance, Sources, Methods and Issues Lisa V. Smith, MS, DrPH Director, Epidemiology Unit Los Angeles County Sexually Transmitted Disease Program
Overview • What are active and passive surveillance? • Which STDs are reportable? • What is the impact of LA County morbidity on state and national STD surveillance? • How are cases reported to LA County (LAC), State, and CDC? • What are “rates” and how are they used? • What are the limitations and benefits of LAC STD surveillance data?
What is Surveillance? Systematic collection and evaluation of: • Morbidity and mortality data • Special reports of field investigation of epidemics and individual cases • Data on the isolation and identification of infectious agents by public or private laboratories • Information regarding immunity levels in certain populations
What do we do with this information? • Estimate the magnitude of health conditions in at-risk populations • Detect sudden changes in occurrence and distribution • Detect changes in drug resistance • Identify changes in health care practices • Evaluate control strategies • Allocate resources
Data Sources • Active SurveillanceConditions of particular importance (outbreaks and epidemics) • Passive SurveillanceRoutine notifiable disease surveillance reported case by case
Active Surveillance • Casefinding: • Prevalence Monitoring • Sentinel Surveillance: K-11, Juvenile Hall, Family Planning Clinics, Bathhouses, Syphilis Elimination Project (MSM) • Mass Screening: Mobile testing, Adult Movie Industry • Epidemiologic research: Primary HIV infection
Passive Surveillance • Accounts for most of the reported cases • Relatively simple compared to active surveillance • Limited by variability and incompleteness • May fail to identify outbreaks • Usually augmented by active surveillance
Health Care Provider Syphilis* Gonorrhea** Chlamydia** Chancroid** PID** NGU** Clinical Laboratory Syphilis (Treponema pallidum) Gonorrhea (Neisseria gonorrhoeae) Chlamydia (Chlamydia trachomatis) Which STDs are reportable? California Code of Regulations, Title 17, Public Health, Section 2500, 1996 *Report by FAX, telephone, or mail w/in one working day of identification *Report by FAX, telephone, or mail w/in seven working days of identification
Reported Sexually Transmitted Diseases United States, 2003 AIDS 43,158 (3.6%) Source: CDC Sexually Transmitted Disease Report, 2001
Reported Sexually Transmitted DiseasesLos Angeles County, 2003 *Provisional data due to reporting delays Source: LAC DHS STD/ACD Programs Provisional Data, 2003
What is the Impact of LAC Morbidity on STD Reportingin CA & US* • 36,555 Chlamydia (31% CA; 4% US) • 8,008 Gonorrhea (31% CA; 2% US) • 442 P&S Syphilis (34% CA; 6% US) • 365 Early Latent (54% CA; 4% US) • 28 Congenital Syphilis (47% CA; 7% US) *LA, CA, CDC STD Surveillance, 2003 P&S:chancres/lesions (90 days-6 months); EL asymptomatic (w/in 12 months)
How are cases reported to the STD Program? • Health providers use forms to report STD cases to the health department • STDP uses a “dual” reporting system to gather information on STD morbidity • Confidential Morbidity Forms (CMRs) • Submitted by health providers • Laboratory Report Forms • Submitted by laboratory facilities
STD Surveillance Process • Case Definition: Differential clinical diagnosis of reportable STDs to distinguish between cases and noncases • Population Definition: Identify area of interest to determine residency and population denominators
LAC STD Program Data Entry/ Field Services Data Cleaning / Transmission Confidential Morbidity Reports (CMR) + Laboratory Slips California Department Of Health Services STD Control Branch Centers of Control and Prevention (CDC) 1. MMWR (Morbidity and Mortality Weekly Report) 2. Requests for Proposals 3. Healthy People 2010 STD Surveillance All CA county reports Public Health Action
85.2 LA (2003) 73.9 CA (2003) 116.2 US (2003)
Why do we use rates and not absolute numbers? • Total number of reported cases appears to be adequate, but are these numbers comparable?
STD Rates multiplier Number of new events in specific period Average population* during specific period X 10n = Essential for comparing dx in different populations: Pop A: 1,000/10,000 = 100 cases per 1000 population Pop B: 1,000/1,000,000 = 1 case per 1000 population *Assumes average population and “population at risk” are comparable.
Population Rates(Males Only) *2000 Estimates
Chlamydia Rates by Gender 2. Describe disease patterns
3. Describe spatial distributions
Additional Resources National Center for Health Statistics • Nation’s principal health statistics agency • Data are used to guide actions and policies, as well as: • Document health status of populations and important subgroups • Identify disparities in health status by race/ethnicity, socio-economic status, region, etc. • Monitor trends in health status and health care delivery • Support biomedical and health research • Evaluate the impact of health care Epi Unit
National Surveillance Reports(www.cdc.gov/nchs) • National Health and Nutrition Examination Survey (NHANES) • Contains important information on sexual behaviors • National Health Interview Survey (NHIS) • AIDS Knowledge and Attitudes Supplement • Young Risk Behavior Surveillance System (YRBSS) (www.cdc.gov/yrbss) • Survey monitors sexual behaviors that contribute to unwanted pregnancies and STD/HIV • UCLA ISSR website: http://www.sscnet.ucla.edu/issr/da/catalog.htm Epi Unit
Data Limitations • Incomplete case reporting • Reporting delays • Missing information • Underreporting (asymptomatic cases) • Reporting bias • Stigmatized condition • Public vs. Private
How Can We Improve Data Quality? • Improve data retrieval system • Phone Shop • Increase provider awareness of reporting regulations • In-services • Mass Mailings • In person visits • Implement CDC NEDSS web-based surveillance Epi Unit
What are the Benefits of STD Surveillance? • Though flawed, STD surveillance data provides • the “best estimate” of magnitude of disease in at-risk populations • Numbers are the “tip” of the iceberg • the basis for epidemiologic research • a system to monitor compliance with CDC treatment guidelines Epi Unit
Key Points to Ponder • To date, six STDs are reportable in California • Chlamydia is the most frequently reported STD in the United States • Los Angeles accounts for 1 of 3 STD cases in California and 1 of 25 cases in the United States • Most of the STD data come from passive surveillance systems and “dual” reporting • Data limitations include incomplete case reporting and reporting bias • Nevertheless, STD surveillance data provides the “best estimate” of magnitude of disease in at-risk populations
Resources • Los Angeles County http://lapublichealth.org/std/ • California http://www.dhs.ca.gov/ps/dcdc/pdf/cdtables/febcm03.pdf • Centers for Disease Control and Prevention http://www.cdc.gov/ • http://www.cdc.gov/nedss/
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