Epidemiological Profile of HIV/AIDS in Minnesota
Epidemiological Surveillance – Data Quality and Sources
HIV/AIDS Reporting System (eHARS)
The Minnesota Department of Health (MDH) collects confidential name-based case reports of HIV infection (since 1985) and AIDS diagnoses (since 1982) through a passive and active HIV/AIDS surveillance system. In Minnesota, laboratory-confirmed infections of human immunodeficiency virus (HIV) are monitored by MDH through this active and passive surveillance system. State law (Minnesota Rule 4605.7040) requires both physicians and laboratories to report all cases of HIV infection (HIV or AIDS) directly to MDH (passive surveillance). Additionally, regular contact is maintained with the following clinical sites to help ensure completeness of reporting (active surveillance): Hennepin County Medical Center and Veterans Administration. Demographic, exposure, and clinical data are collected on each case and entered into Minnesota’s HIV/AIDS Reporting System (eHARS) database developed by the U.S. Centers for Disease Control and Prevention (CDC).
Factors that impact the completeness and accuracy of HIV/AIDS surveillance data include: compliance with case reporting, timeliness of case reporting, test-seeking behaviors of HIV-infected individuals, the availability and targeting of HIV testing services, and the willingness of persons recently diagnosed with HIV to be interviewed by DIS.
Given the long period of time between infection with HIV and the clinical manifestation of AIDS, patterns of new HIV case reports are believed to describe the current epidemic more accurately than AIDS case reports. The introduction of highly active antiretroviral therapies in the mid-1990s further delayed the onset of AIDS for many patients and makes AIDS case reporting a weak tool for describing the present epidemic. Including AIDS case reports is useful for looking at the whole epidemic or trends over time.
While HIV case reports do represent persons more recently infected than AIDS case reports, there are still several limitations that affect the completeness and timeliness of the data. There are multiple ways for a case to be undetected by the state surveillance system promptly after seroconversion.
Tribal health centers are exempt from this reporting requirement. However, a recent survey of tribal health directors found that most of these facilities report new HIV cases on a regular basis (data not published) (MDH, 2005).
CDC has refined the case definition for AIDS over the years. The most recent change to the case definition occurred in 1993 when (in conjunction with confirmed HIV infection) tuberculosis, recurring pneumonia, invasive cervical cancer, or a CD4 count of less than 200 (or below 14% of lymphocytes) joined 23 other AIDS-defining infections/conditions.
First, CDC estimates that about 20 percent of HIV-infected individuals are unaware of their status. And for gay/bisexual men, evidence suggests this percentage is much higher (77 percent) (MacKellar et al., 2002). This is partly because early HIV infection does not produce severe nor distinct symptoms and so delays in testing are common. Additionally, many people acknowledge avoiding testing for fear of a positive test result or because they believe that they are not at risk.
Second, cases of new HIV infection can also go undetected by disease surveillance due to the availability of anonymous testing. Once a person begins care, however, other HIV/AIDS surveillance reporting mechanisms would most likely detect the case. Thus, although HIV case reporting is our best estimate of new HIV infections, the system does not capture all new cases and there are varying amounts of delay between infection, testing, and reporting.
New testing methodologies are becoming more widely available and will enable more timely descriptions of the epidemic as it continues to unfold. In addition, continued efforts to encourage testing and counseling help limit the amount of undiagnosed HIV infection.
MDH collects a small amount of behavioral data as it relates to HIV and AIDS surveillance information. For example, reports of HIV infection received by MDH include information on drug use and sexual behaviors. Additionally, from time to time MDH will undertake special projects with the intent of collecting behavioral data on specific populations. Examples of these are the 2001 Minnesota STD Prevalence Study (ages 12-24) and the 2004 and 2007 Twin Cities Men’s Health Surveys (MSM 18 and older) and the 2011 Minnesota Men’s Health Study (MSM 18 and older).
Other Data Sources
Data regarding risk factors for acquiring HIV that are presented in this report include sexually transmitted disease rates (Epidemiology and Surveillance Unit, STD and HIV Section, MDH), teen pregnancy rates (Minnesota Center for Health Statistics), chemical health indicators (Minnesota Behavioral Risk Factor Surveillance System), behavioral survey data (Minnesota Student Survey and Minnesota Behavioral Risk Factor Surveillance System), a variety of social and economic data from the 2010 Census (U.S. Census Bureau), and results from specific scientific studies. These data serve to characterize the population at risk for acquiring or transmitting HIV.
Mode of Exposure
Cases can have unspecified risk for two reasons. The first is that the person has not yet been interviewed or has refused an interview by a Disease Intervention Specialist (DIS) from MDH, and therefore we have little information on their risk category. Disease Intervention Specialists have reported difficulty interviewing recent cases due to language and cultural barriers, as well as difficulty locating the individuals. Second, the person may have no obvious risk. However, heterosexual contact as a mode of HIV transmission is only assigned when the person knows that their partner was HIV-infected or at increased risk for HIV. Often this level of knowledge about sexual partners (anonymous, casual, or exclusive) may be unknown. According to a study conducted by the CDC, it is likely that at least 80 percent of women with unspecified risk acquired HIV through heterosexual contact (Lansky et al., 2001).
In 2004, MDH began estimating mode of exposure for cases with unspecified risk in its annual PowerPoint summary slides. In 2011, estimation was done by using the risk distribution for cases reported between 2009 and 2011 with known risk by race and gender and applying the distribution to those with unspecified risk of the same race and gender. For females a step was added in 2007, whereby females that were interviewed by a DIS and determined not to have any risk other than heterosexual exposure were designated as having heterosexual mode of transmission. There are two exceptions to this method, African-born cases and Asian/Pacific Islander women. For both African-born and Asian/Pacific Islander women, a breakdown of 95 percent heterosexual risk and 5 percent other risk was used. For African-born males, a breakdown of 5 percent male-to-male sex, 90 percent heterosexual risk, and 5 percent other risk was used. These percentages are based on epidemiological literature and/or community experience.
HIV Treatment Cascade
As part of the National HIV/AIDS Strategy for the United States, MDH began calculating an HIV Treatment Cascade (PDF: 952KB/2 pages) in 2012 using HIV surveillance data. These calculation help us better understand the HIV epidemic and the disparities that exist in the delivery of care among HIV positive people in Minnesota.
Laboratory data are used as a proxy for a care visit to calculate each segment of the treatment cascade. The accuracy of the cascade depends on complete reporting of laboratory results. The transition from voluntary reporting of CD4 and VL results to mandated reporting in 2011 has occurred at different rates among the various reporting laboratory facilities. We have been made aware of at least one lab in the state that has had difficulty consistently reporting all CD4 and VL results which could potentially bias the results. We also know that patients who have laboratories drawn as part of research studies are not reported to MDH. One clinic estimates that approximately 90 of their patients are participating in a research study.
Linkage to Care
Linkage to care is defined as those who were diagnosed in Minnesota during the year 2011 and had a CD4 or VL test performed within 90 days of initial diagnosis. Calculation of the linkage to care measure use a denominator that is different due to guidance from CDC that instructs local jurisdictions to make this calculation based on one year of diagnoses. Therefore results for this measure are displayed in a different color in the graphics.
Glossary of Terms
Greater Minnesota: All counties outside of Transitional Grant Area. The counties include: Aitkin, Becker, Beltrami, Benton, Big Stone, Blue Earth, Brown, Carlton, Cass, Chippewa, Clay, Clearwater, Cook, Cottonwood, Crow Wing, Dodge, Douglas, Faribault, Fillmore, Freeborn, Goodhue, Grant, Houston, Hubbard, Itasca, Jackson, Kanabec, Kandiyohi, Kittson, Koochiching, Lac qui Parle, Lake, Lake of the Woods, Le Sueur, Lincoln, Lyon, McLeod, Mahnomen, Marshall, Martin, Meeker, Mille Lacs, Morrison, Mower, Murray, Nicollet, Nobles, Norman, Olmsted, Otter Tail, Pennington, Pine, Pipeston, Polk, Pope, Red Lake, Redwood, Renville, Rice, Rock, Roseau, Saint Louis, Sibley, Stearns, Steele, Stevens, Swift, Todd, Traverse, Wabasha, Wadena, Waseca, Watonwan, Wilkin, Winona, and Yellow Medicine counties.
HIV Infection: Includes all new cases of HIV infection, both HIV (non-AIDS) and AIDS at first diagnosis, diagnosed within a given calendar year.
Incidence: The number of new cases of a disease that occur in a population during a certain time period, usually a year.
Late Tester: Persons with an AIDS diagnosis within one year of initial HIV infection diagnosis
Linkage to Care: Linkage to care is defined as those who were diagnosed in Minnesota during the year 2011 and had a CD4 or VL test performed within 90 days of initial diagnosis.
Pediatric case: Children less than 13 years of age at time of diagnosis.
Detailed methodology available in the HIV Surveillance Technical Notes