STD Screening in HIV Clinics: Value and Implications

Thomas Farley, MD MPH

Tulane University

Deborah Cohen, MD MPH

RAND Corporation

Background (1)Sexual Activity in HIV+ Persons

Much emphasis in U.S. response to the AIDS epidemic is on identification, referral, and treatment of HIV-infected persons; however...

…many HIV-infected persons continue to be sexually active after diagnosis and during treatment

HIV prevention strategies should include intensive counseling to HIV-infected persons who continue to practice unprotected sex

Identification of these persons needed

Background (2)STDs in HIV+ Persons

Curable STDs facilitate the spread of HIV infection

Diagnosis and treatment of curable STDs in HIV-infected persons helps prevent HIV infection in partners, even when infected persons continue unprotected sex

STD screening and treatment in HIV clinics is essential part of overall strategy for HIV prevention

Still, routine STD screening does not occur in most HIV clinics

CDC Guidelines:“HIV Prevention Through Early Detection and

Treatment of Other Sexually Transmitted Diseases”*

“Persons already infected with HIV should be screened routinely for STDs…including gonorrhea, chlamydial infection, syphilis, and -- among women -- trichomoniasis… Screening frequency should be at least yearly if any potential risk exists for STD acquisition. It should be performed more frequently if any incident STDs are detected by symptoms or screening. These services should be provided as part of and at the site of routine, quality HIV care. “

*MMWR 1998;47(RR12):1-24.

Background (3)STD Screening in HIV+ Clinic in New Orleans

In October 1998, HIV/STD Programs in Louisiana began offering routine gonorrhea and chlamydia screening to HIV Outpatient Program (HOP) in New Orleans

Screening by urine-based Ligase Chain Reaction (LCR) test

Clinic: 2,500 active patients, 12,000 visits per year; 22% CD4 count < 200

Protocol routine urine screening at initial and biannual visits; but up to provider to order tests

Objectives

To determine the prevalence of gonorrhea and chlamydia and secular trends in prevalence among HIV-infected persons in care

To assess relationship between STD prevalence in HIV-infected persons and STD rates in general population

To assess value of continued routine STD screening in HIV clinics

Methods Analyzed data from gonorrhea/chlamydia laboratory slips from

October 1998 - June 2001

Obtained data on number of visits and number of active patients from HOP clinic billing database

Compared HOP clinic results to screening of convenience samples of persons 18-29 in New Orleans as part of unrelated study

Compared HOP results to city-wide trends in gonorrhea and chlamydia obtained from Louisiana Office of Public Health

Relationship Between Visits and TestsHIV Outpatient Program, New Orleans,

October 1998- June 2001

• 34,837 visits – Includes initial, routine follow-up and problem-

focused visits

• 2,629 tests - 7.5% of visits

• Type for visit not available on lab test slip

Percentage of Active Patients TestedHIV Outpatient Program, New Orleans, June 2000-May 2001

25%176708White Males

33%8372,555Total

92

964

707

Patients*

White Females

Black Males

Black Females

45%41

31%297

41%292

% TestedTested*

* Unduplicated count for 12-month period

Prevalence of STDs HIV Outpatient Program, New Orleans, 1998-2001

Tested Positive % Positive

Gonorrhea 2,629 46 1.7%

Chlamydia 2,629 56 2.1%

Prevention Benefit of STD Screening

• Based on mathematical model* of the effect of STD treatment on HIV transmission:– Treatment of 46 HIV-infected persons with

gonorrhea prevents 7 cases of infection in partners

– Treatment of 56 HIV-infected persons with chlamydia prevents 12 cases of infection in partners

– Total: prevention of HIV/AIDS in 19 persons

* Adapted from Chesson and Pinkerton. JAIDS 2000;24:48-56

Prevalence of STDs by Race and SexHIV Outpatient Program, New Orleans, 1998-2001

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

Gonorrhea Chlamydia

Pre

vale

nce

(%)

Black Female White Female Black Male White Male

Prevalence of STDs by Age GroupHIV Outpatient Program, New Orleans, 1998-2001

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

9.0%

10.0%

15-19 20-24 25-29 30-34 35-39 40-44 45-49 > 50

Age Group

Pre

vale

nce

(%)

Gonorrhea Chlamydia

Convenience Sample to Estimate Population Prevalence of STDs

• Persons offered urine-based screening for gonorrhea, chlamydia, and HIV

• May 1999 – July 2000• Sampled from 10 sites in New Orleans, including:

– Hospital emergency rooms and walk-in clinics– Dental clinic– Colleges– Facility for homeless youth– Vo-tech school

• Excluded persons seeking care for genitourinary symptoms

• Age 18-29 only; 82% Black, 14% White• N=1,610

Gonorrhea Prevalence vs Convenience Sample of General Population

New Orleans

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

15-19 20-24 25-29 30-34 35-39 40-44 45-49 > 50

Age Group

Gon

orrh

ea P

reva

lenc

e (%

)

HOP Population

Chlamydia Prevalence vs. Convenience Sample of General Population

New Orleans

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

14.0%

15-19 20-24 25-29 30-34 35-39 40-44 45-49 > 50

Age Group

Chl

amyd

ia P

reva

lenc

e (%

)

HOP Population

Secular Trends in PrevalenceHIV Outpatient Program, New Orleans, 1998-2001

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

1998 1999 2000 2001

Year

Pre

vale

nce

(%)

Gonorrhea Chlamydia

Trends in Prevalence Among Persons < 30HIV Outpatient Program, New Orleans, 1998-2001

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%

9.0%

1998 1999 2000 2001

Year

Pre

vale

nce

(%)

Gonorrhea Chlamydia

Trends in Prevalence Among Persons > 30HIV Outpatient Program, New Orleans, 1998-2001

0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2%

1.4%

1.6%

1998 1999 2000 2001

Year

Pre

vale

nce

(%)

Gonorrhea Chlamydia

Comparison of Trends in Gonorrhea HOP Prevalence vs. Surveillance Data

New Orleans, 1998-2001

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

1998 1999 2000 2001

Year

Pre

va

len

ce

at

HO

P

0

100

200

300

400

500

600

700

800

Ca

se

s p

er

10

0,0

00

in N

ew

O

rle

an

s

HOP New Orleans

Comparison of Trends in ChlamydiaHOP Prevalence vs. Surveillance Data

New Orleans, 1998-2001

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

1998 1999 2000 2001

Year

Pre

va

len

ce

at

HO

P

0

100

200

300

400

500

600

700

800

900

1000

Ca

se

s p

er

10

0,0

00

in N

ew

O

rle

an

s

HOP New Orleans

Summary

• Among HIV-infected persons in care, 1.7% had gonorrhea and 2.1% had chlamydia

• Treatment of these infections prevented an estimated 19 cases of HIV/AIDS in partners

• STD prevalence did not vary substantially by race or sex, but was higher in persons under age 30

• STD prevalence was similar to that of general population

• STD prevalence varied over time in parallel with population STD rates

Conclusions

• Routine STD screening in HIV clinics is feasible• Screening and treatment for gonorrhea and

chlamydia in HIV clinics prevents substantial number of HIV infections, even when prevalence is ~2%.

• HIV-infected persons in care continue to practice high risk sexual behavior, probably at about the same level and in the same sexual networks as the general population

• STD screening in HIV clinics identifies persons with curable STDs who can be treated and intensively counseled to prevent transmission of HIV to others

Recommendations

• Routine STD screening should be established in all HIV clinics, following CDC guidelines

• Intensive counseling and partner notification should be implemented for HIV-positive persons in care who have STDs

• Prevention of STDs in the general population should be considered an HIV prevention strategy, as it should lead to lower STD rates in HIV-infected persons and thus less HIV transmission