Petrelis Files

SF DPH, CDC Rep: UCSF Gay Staph
Study Guilty of "Ascertainment Bias"

If the issue is gay men and communicable diseases in San Francisco, especially related to homo-sex, Jeffrey Klausner, the head of DPH's STD control unit, likes to rule over such issues like the queen bee controlling her territory. He just doesn't like anyone encroaching on his domain -- fags and diseases. This may be one motivating factor behind Klausner co-signing a letter to the Annals of Internal Medicine ripping into the UCSF gays and staph infections study recently published in the journal.

Klausner's stormy and stigmatizing campaigns have included social marketing campaigns equating people with syphilis with time-bombs, considering quarantine and closing gay sex venues, and demonizing gays and people with AIDS who use erectile dysfunction medications.

From the November 21, 2001, Washington Monthly:

Dr. Jeffrey Klausner [...] has suggested a number of measures, some coercive,which he thinks would slow the increase of new HIV infections among gay men. Among them: closing sex clubs and adult bookstores; enforcing no-sex ordinances in bars and clubs; enforcing no-drug policies in bars and clubs; and Internet-based outreach and education, particularly in chat rooms where many gay men meet new sexual partners.

Putting aside political realities when brainstorming on this subject, Klausner also raised the possibility of quarantining those who cannot control their infectivity---e.g., those barebackers who've infected 20 different people and still refuse to use condoms.

From the August 18, 2005, edition of the Bay Area Reporter:

AIDS czar Jeff Sheehy said the push by a city health official to make erectile dysfunction medications Schedule III drugs is AIDSphobic and homophobic. He has asked the city's Human Rights Commission to investigate the appropriateness of using city funds to advance the criminalization of Viagra use by gay men, particularly gay men with HIV. [...]

"Jeff Klausner wants the dicks of people with HIV in his back pocket and he wants us to ask him permission to use it. And I am not giving him my dick," said an outraged Sheehy, a gay HIV-positive man who volunteers as Mayor Gavin Newsom's adviser on HIV and AIDS policy. "Jeff Klausner is specifically targeting gay men with HIV. This is not what city funds should be used for. There is no science to justify this."

But today I will say something nice about Klausner, and that is I appreciate his letter in the Annals of Internal Medicine, calling into question what he says is the "ascertainment bias" of the UCSF research and findings.

What exactly is this bias? From Wikipedia:

In scientific research, ascertainment bias occurs when false results are produced by non-random sampling and conclusions made about an entire group are based on a distorted or nontypical sample. If this is not accounted for, results can be erroneously attributed to the phenomenon under study rather than to the method of sampling.

Published February 15, 2008, in the Annals of Internal Medicine:

In their population-based survey (1), Diep and colleagues report a higher incidence of a multidrug-resistant (MDR), community-associated (CA), methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 infections in the ZIP code that includes the Castro district, compared with San Francisco overall (170 versus 26 cases/100,000 persons, respectively) during 2004–2005. We are concerned that this finding reflects, at least in part, ascertainment bias rather than a true difference in disease incidence.

Diep and colleagues defined cases as positive MDR CA-MRSA USA300 clinical cultures other than nasal swabs. Clinical considerations determined whether cultures were performed. Because all infections might not have been cultured, Diep and colleagues state that they might have underestimated the true incidence.

The magnitude of underestimation probably differed importantly among groups as a result of ascertainment bias. Bias likely stemmed from greater awareness of MRSA infections among gay men and other men who have sex with men (G/MSM) and their health-care providers.

In February 2003, articles in two widely read local newspapers — the San Francisco Chronicle and the gay-oriented Bay Area Reporter (BAR) — highlighted MRSA infections among G/MSM in San Francisco. In the San Francisco Chronicle, a prominent physician recommended culturing all infections; the front-page BAR article encouraged persons with suspected infections to seek treatment early. The San Francisco Department of Public Health issued frequently asked questions for the public and a Health Advisory for clinicians and, with community partners, hosted a forum, all focusing on MRSA infections among G/MSM. Additionally, journal articles published during 2003–2005 linked MRSA infections to G/MSM (2), including HIV-infected G/MSM (3).

All these factors increased the likelihood both that G/MSM sought health care for suspected MRSA infections and that clinicians cultured suspected MRSA infections among G/MSM San Franciscans. That bias, plus the fact that G/MSM in San Francisco (including HIV-infected G/MSM, who comprise a majority of HIV-infected city residents) are a large, geographically concentrated group (4), likely resulted in a relative overestimation of the incidence of infections in the Castro district, compared with other ZIP codes in San Francisco.

Additionally, Diep and colleagues provide evidence that among patients of a San Francisco HIV clinic who had an MRSA USA 300 infection, G/MSM were more likely to have an MDR strain of USA300 compared with non- G/MSM. However, G/MSM at that clinic are unlikely to be representative of G/MSM throughout San Francisco.

Kenneth A. Katz, MD, MSc, MSCE

Epidemic Intelligence Service, Centers for Disease Control and Prevention Atlanta, GA 30333 San Francisco Department of Public Health San Francisco, CA 94103

Kyle T. Bernstein, PhD, ScM

San Francisco Department of Public Health San Francisco, CA 94103

Jeffrey D. Klausner, MD, MPH

San Francisco Department of Public Health San Francisco, CA 94103

Note: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the Centers for Disease Control and Prevention.

This letter, and the authors' affiliations, should help generate additional coverage of the gay and staph story.