25 Feb 2010


One day, learning that an assistant of a rather demanding senior doctor left her job, GW wondered aloud, “Why doesn’t the remaining assistant quit, too?”

“Stockholm syndrome.” I replied slyly.

Stockholm syndrome was coined by criminologist Nils Bejerot after the famous Norrmalmstorg robbery in Stockholm in August 1973. During the event, bank robber Jan Erik Olsson took four people as hostages for six days. While the victims naturally persuaded the government to follow Olsson’s request when they were held captive, it was remarkable that they continued to defend the robber after he surrendered. With strong emotional bonding, the hostages still claim they feared the police more than Olsson.

At present, Stockholm syndrome refers to a psychological phenomenon in which hostages develop irrational positive feelings towards their captors. Although the pathogenesis of the syndrome is not completely understood, there are a few prerequisites. The captor is considered to have the power to kill and grant lives by not killing. The hostage is isolated from other people. Importantly, the captor shows some kindness towards the hostage. As a result, the hostage perceives that his/her survival is linked to the captor.

In real life, we seldom meet fully-armed villains. However, I cannot help but think that we are often similarly bound to old habits and stubborn decisions for the same reasons. Failing to think outside the box, we are isolated from alternatives and exaggerate the danger of change and the merit of the present state.

18 Feb 2010


J. D. Salinger passed away last month. His best known novel was The Catcher in the Rye.

The main character, Holden Caulfield, was a boy expelled from a preparatory school. The story was about his observation and thoughts while he wandered in New York for three days, not wanting to return to his parents yet. Disgusted by the adult world, he was considered an icon of teenage rebellion and confusion.

At the end of the story, Holden had a long discussion with his younger sister Phoebe. He pictured a scenario where many children were playing some games in a huge rye field next to a cliff. His dream work would be a catcher in the rye, saving children from falling down the cliff. In essence, he wanted to stop children from becoming ugly and superficial adults.

When I was a medical student, a local doctor wrote a very popular book called I am an Intern. Overall, the book was informative. However, one chapter depressed me. The author thought that senior doctors talked about caring for patients only because they had passed all the examinations and had less workload. This can be a slippery slope phenomenon. If one can accept not treating patients by heart because he has to prepare for examinations, he will have even more excuses later. Administrative work, specialty duties, research, you name it.

I feel warm whenever I see young doctors and students chatting with patients and really listening to them. I may not be a good catcher, but please, don’t fall down the cliff.

11 Feb 2010


Recently, our government officials were asked about incidents of Guillain-Barre syndrome and intrauterine deaths in people who received the new swine flu vaccine. Every time, their response was monotonous. “There is no evidence that the risk of Guillain-Barre syndrome (or intrauterine deaths or any complications, depending on the original question) is increased with the use of the vaccine.”

According to the tone of the media, their claim was hardly reassuring. Many still fear that the government is tricking them to use an unsafe product. (The effect was better illustrated at http://ccszeto.blogspot.com/2010/01/armor.html.) Although I do not really think the vaccine is dangerous, I have the uneasy feeling that the government may intentionally or unintentionally confuse the public.

In evidence-based medicine, the lack of evidence can never be used as evidence against a concept or hypothesis. For example, if no one has ever tested a drug in a certain disease, you can just say you do not know if it works but cannot state it does not work. The same also applies to harm. If you never look for the harm, how would there be evidence?

In the last two months, the efficacy data of the swine flu vaccine became available. [Greenberg et al. N Engl J Med 2009;361:2405-13, Zhu et al. N Engl J Med 2009;361:2414-23, Clark et al. N Engl J Med 2009;361:2424-35, Arguedas et al. N Engl J Med 2010;362:370-2, Nolan et al. JAMA 2010;303:37-46] Notably, all these studies excluded pregnant women. Similar to our government, WHO and CDC also encourage pregnant women to receive the new vaccine and reassure the public that studies on pregnant women are ongoing. If we search ClinicalTrial.gov, we can see that a handful of studies are recruiting pregnant women to try different brands of the swine flu vaccine. Each study recruits around 150 to 300 women. Thus, in the end we probably will have safety data of 1000 to 2000 women. It is reassuring, isn’t it?

This leads to the question of statistical power. In 2003, data from the US National Center for Health Statistics showed an average fetal mortality rate of 6.9 deaths per 1000 births. Using online calculators, we can estimate that a sample size of 2000 subjects can achieve a confidence level of approximately 0.5% at a 95% confidence interval. Although this confidence level is already respectable, it also means that we can conclude the new vaccine causes harm only if the rate of fetal death has doubled. Therefore, the importance of post-marketing surveillance cannot be overemphasized.

In the end, the vaccine probably will result in more benefit than harm at the community level by reducing the number of people infected with the virus. However, the risk-to-benefit ratio is less certain at the individual level. People who stress the mortality rate of swine flu is higher than the harm of the vaccine should consider the fact that people not receiving the vaccine may not contract the virus at all. While the motives of various health authorities are understandable, mixing up the above concepts can be misleading.

4 Feb 2010


Thank you all for your greetings last week. In fact, I secretly removed my birthday from my Facebook profile earlier on and realized that my friends could still see it. This is probably a good example of my aging mind. Other examples may include:

- Silly enough to tell my wife that another woman was very beautiful. (She was Martha Argerich.)
- I thought Bach was boring when I learned piano. Now it has become my prayers.
- I can no longer recite any new music work.
- When I was a student, I once went to the medical clinic and requested to follow Szeto. He threw me out of the room. I was really angry then but can now see his point.
- I stopped wearing ties on Saturdays and thought that was quite sporty.
- I zoomed to 150% when I typed this.