MSM in Hong Kong

MSM does not mean MainStream Media in this post.  Instead, it means Men Having Sex With Men.

The starting point is this Ming Pao ad taken out by the Truth & Light Society.  I found this from Miss Lee, Sinan and Seechuen.

Two sets of numbers are cited in this ad.  

The first set of numbers is derived from Lau, J.T., Lau, M. and Tsui, H.Y.  HIV related behaviors and attitudes among Chinese men who have sex with men in Hong Kong: a population-based on study.  Sex. Transm. Infect., 2004 Dec: 80(6), 459-465.  The data are summarized in the schematic diagram below.  Please be mindful that I have not read the original paper, and do not know if there are more complex sampling issues involved here.  I only have this diagram to go by.

The second set of numbers comes from a press release from the Virtual AIDS Office of Hong Kong.  The data are as follows:

A total of 268 HIV cases were reported to the Department of Health (DH) last year. ...  Of these cases, 107 involved heterosexual transmission and 65 occurred between men having sex with men.  "Under the voluntary reporting system, some 28 per cent of the reports were incomplete, making the determination of the route of infection impossible,'' Dr Lee said.

Now I will translate for you what the ad asserts:

A survey conducted in Hong Kong estimates that 4.6% of men had engaged in MSM.  In the past 6 months, about 2% had engaged in MSM.

According to the information provide by the government, during 2004 there were 172 cases of new HIV cases that occurred as a result of sexual contact.  Of these, 65 were infected via MSM behavior.

In other words, the male homosexuals account for only 2% of the population accounts for 37.7% of the new HIV cases in 2004.  Based upon these figures, the odds ratio of MSM to heterosexual behavior in causing HIV infection is 29:1.

 Let us do these numbers line by line.

The Truth & Light Society ad was signed by a whole lot of healthcare and medical professionals who placed their names onto a petition based upon scientific data and arguments.  The data may be scientific but the statistical inference is wrong.  And this is not exactly rocket science because the survey universes are clearly different.  These people must have put their signatures down without even looking at the statements.  Think about that kind of professionalism the next time that you visit a doctor.

Since this is paid advertisement and the information is wrong, it is false advertising.  Both the advertiser and the newspaper have liabilities as such.

Message to MSM (mainstream media in Hong Kong): This is scandalous.  Will you pick it up and report it?