Conclusions and Statistical Analysis

Glancing at Allan Parachini's story on the front page of the View section ("Hepatitis: Homosexual's New Scourge," June 11), one would think that delta virus hepatitis posed a special risk to gay men in the same way that the AIDS epidemic does.

But the statistics quoted in the continuation of the report tell a different story. After discussing the incidence of delta virus hepatitis among intravenous drug users, Parachini goes on to write:

"Slightly more than 10% of the cases, however, have proven to involve male homosexuals and almost exactly 10% include victims who are both homosexual and intravenous addicts. . . . The rest of the cases either lead to no identifiable risk factor or could not be completely evaluated."

It is bad science to jump to the conclusion that male homosexual activity is a risk factor for delta virus hepatitis from this data alone. One also needs to know what fraction of the general population are male homosexuals. In order to demonstrate that male homosexuality is a risk factor, one must show that there is a significantly higher fraction of gay men who are delta hepatitis victims than there is of gay men in the general population. The fraction of the general population that is gay is difficult to pin down (obviously, many are not going to be open about it), but my understanding is that the figure is somewhere about 10%. This estimate is supported by the statistics quoted--that the proportion is the same among homosexual addicts and homosexual non-addicts suggests that this is just the statistically expected fraction of the sample of the disease victims who happen to be homosexual males.

I believe that if Dr. Allan Redeker, who gave these figures to Parachini, is concluding that male homosexuality is a risk factor for delta virus hepatitis, his conclusion will not stand up to sound statistical analysis. He should not have reported these conclusions to the public before the peer review process has had a chance to catch his error. Parachini's story serves only to incite an atmosphere of fear around the gay community, which has no scientific basis.



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