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Statistics for Business and Economics: Excel/Minitab Enhanced
Heinz Kohler
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Statistics in the News: Chapter 12 Estimation

Assessing Drugs to Fight Alzheimer's Disease

Pharmaceutical companies are forever searching for new and better drugs that may dramatically impact their profits. For that reason, they seek to learn all they can about the causes of diseases and how these causes might respond to various drugs. One recent study sought to shed light on the hypothesis that inflammatory mechanisms play a major part in Alzheimer's disease. Thus, anti-inflammatory drugs might prevent it.

The 8-year study involved 6,989 subjects 55 years and older—all of whom were initially free of dementia. The subjects were observed taking different doses of nonsteroidal anti-inflammatory drugs, known as NSAIDs, including Diclofenac, Ibuprofen, Naproxen, and others. Within the group of subjects, 394 eventually developed one kind of dementia or another: 293 Alzheimer's, 56 vascular dementia, and 45 other forms of dementia. Crucial results are summarized in Table A.

TABLE A Results of NSAID Study

 

 

Cumulative Drug Use

 

Sample

Size

Developed

Any Type of

Dementia

Relative Risk Ratio for Alzheimer's

95% Confidence

Interval for Alzheimer's Ratio

None

2,553

210

1.00

--

Short-term

(up to 1 month)

2,001

88

.95

.70 - 1.29

Intermediate term

(>1 month but < 24 months)

2,202

93

.83

.62 - 1.11

Long term

(24 months and more)

233

3

.20

.05 - .83

Total

6,989

394

   

The numbers found in the last two columns cannot be computed from the remaining numbers shown here, but they clearly indicate that — in comparison with taking no anti-inflammatory drugs — the risk of getting Alzheimer's appeared to fall with NSAID use, the more so the longer the use.

Caution: The preceding results were not obtained with the help of a randomized controlled experiment. They come to us from a mere observational study, possibly subject to numerous confounding factors. A controlled experiment, however, has recently been initiated. To learn more about this Alzheimer's Disease Anti-inflammatory Prevention Trial, visit http://www.2stop.AD.org.

Sources: Adapted from Bas A. In 't Veld at al., Nonsteroidal Anti-inflammatory Drugs and the Risk of Alzheimer's Disease," The New England Journal of Medicine, November 22, 2001, pp. 1515-1521, and John C. S. Breitner and Peter P. Zandi, "Do Nonsteroidal Anti-inflammatory Drugs Reduce the Risk of Alzheimer's Disease?" ibid., pp. 1567-1568.


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