# Presentation: 679897

## The Case for Routine Screening for HIV

- Douglas K. Owens, MD, MS
- VA Palo Alto Health Care System, Palo Alto, CA USA
- Stanford University, Stanford CA, USA
- June 2007
- Supported by the Department of Veterans Affairs, the VA HIV QUERI,  and the National Institute on Drug Abuse

## Should voluntary HIV screening be expanded in the U.S?	

- Background
- Burden of HIV in health-care settings
- Are at risk patients being tested?
- What is the prevalence of undocumented HIV disease?
- What are the costs and benefits of HIV screening?
- Benefit to a person identified as having HIV
- Benefit from reduced transmission of HIV

## Identification early in the course of HIV disease is critically important

- Access to highly active anti-retroviral treatment (HAART)
- Prophylaxis for opportunistic infections
- Counseling to reduce HIV transmission

## But, HIV infection is often diagnosed late in the course of disease

- CDC Surveillance: 41% of patients develop AIDS within a year of diagnosis with HIV
- VA: 40% have CD4 count < 200 at diagnosis
- Up to 20,000 new infections in the U.S from people unaware they are infected (CDC)

*The system for detecting HIV in the U.S. is inadequate *

## CDC and US Preventive Service Task Force Recommend Screening

- CDC, prior to September 2006:
- Assess risk behaviors; screen high risk
- Routine voluntary screening if prevalence is 1% or greater
- CDC, current
- Routine screening all health care settings (prevalence over 0.1%)
- USPSTF: Screen high risk people and pregnant women
- Consider prevalence in determining policy

## Two approaches to screening: targeted or routine screening

- Targeted screening: assess risk behaviors, screen if high risk
- MSM
-  IDU
- Multiple partners
- Exchange sex for money or drugs or have partners who do
- Past or present partners HIV-infected, bisexual, or IDU
- History of STD
- Blood transfusion between 1978-1985
- Requests testing

## Routine screening offers screening to all people in a specified clinical setting

- Defined by type of setting
- STD clinics
- Homeless shelters
- TB clinics
- Clinics serving MSM
- Defined by prevalence
- CDC: 1% prevalence (early 90’s)

## Targeted screening: Why not just assess risk behaviors?

- 10% to 25% of people testing positive report no risk behaviors1
- Prospective study2 in STD clinic: testing only those with reported risk behaviors missed 75% of HIV diagnoses
- Risk assessment likely less reliable in high risk populations

- 1Chou et al, Ann Intern Med 2005; 143:55-73; 2Chen et al. Sex Trans Dis 1998; 25:539-43

## Routine screening: Why not screen everyone?

- Potential disadvantages:
- Medical harms: false-positive test result
- Cost
- Competing health care priorities

## Summary: We are failing to identify people with HIV early in disease.

- They lose opportunity for maximum benefit from ARV
- Increased ongoing transmission
- Targeted or routine screening?

## Should voluntary HIV screening be expanded in the U.S?	

- Background
- Burden of HIV in health-care settings
- Are at risk patients being tested?
- What is the prevalence of undocumented HIV disease?
- What are the costs and benefits of HIV screening?
- Benefit to a person identified as having HIV
- Benefit from reduced transmission of HIV

## Are at risk patients being tested? 

- Used VA National Patient Care database to identify cohort seen at 4 VA medical centers from October 1, 1998 to September 30, 1999
- At risk defined as documentation of ICD9 codes for substance use, STD or hepatitis
- HIV testing information from October 1, 1995 to September 30, 2000 obtained for cohort

## Have at-risk patients been tested for HIV?

**Among at-risk patients, 36% had been tested for HIV**

## Are primary care patients at risk?

- Randomized trial of screening in primary care
- Reviewed charts of 750 UNTESTED patients
- 25% had HIV risk behaviors
- Of patients with risk behaviors, only 15% had risk assessment

*Many patients were at risk, few had risk assessment, none were tested.*

## Should voluntary HIV screening be expanded in the U.S?	

- Background
- Burden of HIV in health-care settings
- Are at risk patients being tested?
- What is the prevalence of undocumented HIV disease?
- What are the costs and benefits of HIV screening?
- Benefit to a person identified as having HIV
- Benefit from reduced transmission of HIV

## The prevalence of HIV infection determines the yield of screening.

- Prevalence of unknown HIV infection is the critical determinant of yield of screening
- Total prevalence may be a reasonable marker for prevalence of unknown HIV infection

## A blinded serologic survey can determine the prevalence of undocumented HIV infection

- Blinded, anonymous serologic survey
- Randomly sampled age-stratified blood specimens drawn for other purposes
- Unique patient specimens for inpatients and outpatients
- Collected data on demographics, comorbid conditions and prior HIV status
- HIV testing done using standard testing protocols after removing all identifiers

## HIV Prevalence: Inpatients

## HIV Prevalence: Outpatients

## Results:  HIV Prevalence

## What is the Prevalence of HIV Among Older Patients?

- Outpatient

- Inpatient

- Outpatient

- Inpatient

- Age group

-    25-44

- 11.4 (9.3-13.7)

-        5.9 (4.2-8.1)

-    1.6 (0.8-2.7)

-        0.8 (0.3-2.0)

-    45-54

-   5.6 (4.4-7.2)

-        5.2 (4.0-6.6)

-    0.9 (0.4-1.6)

-        0.6 (0.3-1.3)

-    55-64

-   3.5 (2.3-5.2)

-        2.8 (1.7-4.3)

-    0.7 (0.2-1.7)

-        0.9 (0.3-1.9)

-    65-74

-   0.8 (0.4-1.6)

-        1.3 (0.6-2.3)

-    0.5 (0.2-1.2)

-        0.4 (0.1-1.0)

-    >= 75

-   0.1 (0.0-0.6)

-        0.2 (0.0-0.9)

-    0.1 (0.0-0.6)

-        0.0 (0.0-0.4)

- HIV Prevalence

- % (95% CI)

- % (95% CI)

- (total)

- HIV Prevalence

- (previously unknown)

## Lessons from the serologic survey

- HIV prevalence at all our sites was substantially higher than the 0.1% prevalence recommended for routine screening by CDC currently
- From 3% to 44% of HIV infections were undocumented and probably unknown.

## Providers aren’t aware their patients are at risk.

- Providers felt testing was not a high priority
- Population not at risk
- One quarter of primary care patients DID have risk behaviors, none were tested

## Should voluntary HIV screening be expanded in the U.S?	

- Background
- Burden of HIV in health-care settings
- Are at risk patients being tested?
- What is the prevalence of undocumented HIV disease?
- What are the costs and benefits of HIV screening?
- Benefit to a person identified as having HIV
- Benefit from reduced transmission of HIV

## Cost effectiveness analysis

- Compares two or more strategies
- Assesses the incremental benefit and incremental cost of one strategy versus another
- Calculate the incremental cost-effectiveness ratio:

- Costs with screening – Costs without screening

- Benefits with screening – Benefits without screening

## Measuring health outcomes: the quality-adjusted life years (QALYs)

- Time spent in a reduced state of health is equivalent to some shorter period of time in good health.

- Moderate angina

- No angina

- 0

- 10 yrs

- 8 yrs

*10 years with moderate angina = 8 years with good health, or 8 “quality-adjusted” years of life.*

## Interpreting the incremental cost-effectiveness ratio

- Less than $50,000 per QALY gained – usually considered good value
- $50,000 to $100,000 per QALY gained – sometimes considered good value
- Greater than $100,000 per QALY gained – often considered expensive

## We evaluated the costs and benefits of screening*

- Potential benefits
- For HIV+: increased length and quality of life
- For community: decreased transmission
- Costs
- Screening and counseling costs
- Costs of treatment (HAART, prophylaxis for opportunistic infections)

- * Sanders et al. NEJM 2005; 352:570-85

## Screening strategies

- No screening
- Testing for HIV only from case finding for symptomatic patients
- HIV screening
- Symptom-based case finding AND
- One-time or recurrent screening

## Methods: A mathematical model of screening

- Mathematical model (Markov model) follows screened and unscreened cohort
- Perspective: societal
- Time horizon: lifetime
- Health benefit: quality-adjusted years
- Costs: U.S. testing and treatment costs

## Markov Model

- Screening and
- Case Finding

## Costs	

- Testing and counseling costs
- Cost of HAART
- Other medical costs of HIV care

## 
Costs and Benefits of Screening

- Costs and Benefits of Screening

## What is the benefit to the person identified as having HIV?

## Lifetime costs and benefits, cost effectiveness, 1% Prevalence, ignoring transmission

| Strategy | Cost | Incremental Cost | QALYs | Incremental QALYs | CE
$/QALY |
| --- | --- | --- | --- | --- | --- |
| No Screening | $51,517 | --- | 18.626 | --- |  |
| Screening | $51,850 | $333 | 18.634 | 2.9 days | $41,700 |
|  |  |  |  |  |  |

## Lifetime costs and benefits, cost effectiveness, 1% prevalence, including transmission

| Strategy | Cost | Incremental Cost | QALYs | Incremental QALYs | CE
$/QALY |
| --- | --- | --- | --- | --- | --- |
| No Screening | $52,623 | --- | 18.576 | --- |  |
| Screening | $52,816 | $194 | 18.589 | 4.7 days | $15,000 |
|  |  |  |  |  |  |

## Effect of prevalence on cost effectiveness of screening

## Screening is cost effective even at low prevalence

- Including transmission, screening is cost effective when prevalence is above 0.05%
- Implication: screening is cost effective in all sites we surveyed, and likely in all but the lowest risk health-care settings

## Screening guidelines revisited

## Slide 40

## Slide 41

## Evidence for routine screening is compelling, but how should it be done?

- Addressed in a HIV QUERI randomized control trial
- Doctor initiated, traditional testing and counseling
- Nurse initiated, traditional testing and counseling
- Nurse initiated, streamlined counseling, rapid testing
- Conducted by Steve Asch, Henry Anaya, Matt Goetz, and colleagues from the HIV QUERI

## Nurse-based screening with rapid testing and counseling out performs other strategies

- MD, traditional
- Nurse, traditional
- Nurse, streamlined counseling, rapid testing

- % Tested		% Received Result

- 40%				15%
- 85%				31%
- 89%				80%

## Summary

- With our current approach to identification of HIV, almost half of people identified late in disease
- Many at-risk patients are seen in health-care settings
- Many are NOT tested

## Summary

- Screening in the US provides substantial health benefit:
- To the HIV+ individual
- To the community – reduced transmission

## HIV Screening programs should be expanded in the U.S

- Screening is cost effective at a prevalence 20 times lower than that previously recommended by the CDC
- Routine screening would be cost effective in most health-care settings
- CDC guidelines for screening in the U.S now recommend screening in all health care settings

## Thanks to the VA HIV Quality Enhancment Research Initiative (QUERI) 

## In collaboration with...

- VA Palo Alto/Stanford: Gillian Sanders, Ahmed Bayoumi, Vandana Sundaram, S. Pinar Bilir, Christopher P. Neukermans, Chara E. Rydzak, Lena Douglass, Patricia Tempio, Dan Margolis, Laura Lazzeroni, and Mark Holodniy
- VA San Francisco/UCSF: Peter Jensen, Vera Shadle, Diane Gyuricza
- VA San Diego/UCSD:Valerie C. McWhorter, Teodora Agoncillo, Paula Paulk, Sam Bozzette
- VA New York: Noreen Haren, Mark Tuen, Anne Dwyer, Mike Simberkoff
- VA Greater Los Angeles/UCLA: Steve Asch, Henry Anaya, Matthew Goetz
- VA New England: Allen Gifford
- VA Memphis: Dennis Dietzen
- VA North Chicago: Jill Nyland, Walid Khayr

## References

- US Preventive Services Task Force. Screening for HIV: Recommendation Statement. Ann Intern Med 2005; 143:32-37.
- Chou et. al., Screening for HIV: A review of the evidence for the US Preventive Services Task Force. Ann Intern Med 2005; 143:55-73.
- Chou et. al., Prenatal Screening for HIV: A review of the evidence for the US Preventive Services Task Force. Ann Intern Med 2005; 143:38-54.
- Sanders GD, et. al., Cost effectiveness of screening for HIV in the era of highly active antiretroviral therapy. N Engl J Med 2005; 352:570-85.
- Paltiel AD, et. al., Expanded screening for HIV in the United States—an analysis of cost effectiveness. N Engl J Med 2005; 352:586-95.

## Slide 50

## Demographic Characteristics of At-risk Cohort

## Predictors of HIV Testing

## Logistic regression model

- Outcome:  HIV infection
- Predictors included in the model were
- Age
- Race/Ethnicity
- Site
- Patient group: Inpatient/Outpatient
- Hepatitis C
- Hepatitis B
- Comorbid conditions:  Alzheimer’s, Liver disease, COPD, Pneumonia, Septicemia, Malignant Neoplasms, STDs, Psychiatric conditions, Heart disease, CVD, Diabetes

## HIV screening program description

- Voluntary
- Informed consent, pre- and post-test counseling
- Healthcare settings
- Counseling to reduce risk behaviors
- Referral to comprehensive care including HAART

## Treatment Model

## Model description

- Health states were characterized by
- Whether HIV was identified
- Disease state (HIV or AIDS)
- Antiretroviral therapy (suppressive or non-suppressive therapy)
- Viral load and CD4 count
- Rates of progression from HIV to AIDS and AIDS to death dependent on CD4 and viral load

## Base-case population

- Prevalence = 1%
- Gender- and age-specific incidence

## Sexual transmission of HIV

- Depended on:
- Number of sexual partners at risk
- Type of sexual acts
- HIV+ person’s viral load
- 1 log increase in viral load increased HIV transmission by 2.45 times

## Effect of knowledge of HIV status

- Identified person reduces risk behavior
- Partners of identified HIV+ person will also be identified and begin treatment when appropriate
- Partner of unidentified HIV+ person identified through symptom-based case finding

## Treatment assumptions

**Identified patients begin HAART when:**
- CD4 count = 350 cells/uL
- Viral load   = 4.6 log copies/mL
**HAART treatment:****	****	****	****	****	**
**	****	****	****	****	****     ****1****st****	****	****2****nd****	****     3****rd**** **
**Virologic suppression, %****	****     80****	****	****65****	****     30**
**2-yr virologic rebound, %****	****     15****	****	****x 2****	****     x 2**
**Intolerance, %****	****	****     25****	****	****x 1****	****     x 1.4**

## What is the effect on HIV transmission?

| Strategy |  | Annual Transmission Rate |  |
| --- | --- | --- | --- |
|  |  | MSM | Heterosexual |
| No screening |  | 2.80% | 2.09% |
| One-time screening |  | 2.22% | 1.66% |
|  | Relative reduction | 21% | 21% |

## HIV Prevalence: Total

## Screening every 5 years can be cost effective, but depends on incidence

## Screening guidelines revisited

- Old CDC: 1% threshold
- Too high
- USPSTF: recommends screening high risk
- Does not recommend for or against routine screening

## Predictors of HIV infection