Wu has successfully used curve estimation in other projects. In one clinical study funded by the National Institute on Drug Abuse, Wu and his former Ph.D. student, Chin-Tsang Chiang, were able to track the day-to-day comfort levels of two groups receiving in-patient treatment for opiate addiction. One group received a medication that researchers hoped would reduce painful withdrawal symptoms. The other group received a placebo. Again, traditional statistical methods could not do the job. "How do you know if one group is doing better on a day-to-day basis?" Wu asks. "There may be no difference between the two groups for the first day or two. Then the patients in one group may feel better. You have to be able to make a valid comparison."
Using curve estimation, Wu produced a picture of how the addicts felt throughout the treatment period. It showed that the medication did indeed ease the pain of withdrawal.
The technique has also proved helpful in cohort studies, which involve long-term tracking of health conditions in a particular group of people. Wu used data from the Multicenter AIDS Cohort Study to determine how the level of CD4 cells -- a critical measure of the strength of the body's immune system -- declined among 400 gay men who were infected by HIV between 1984 and 1991.
Wu was able to produce charts that will enable physicians to predict how quickly
these cells will decline. This information will help doctors and patients plan
an appropriate course of
Contact: Phil Sneiderman
Johns Hopkins University