A really neat study was by Silverman and colleagues from the New England Journal in 1992, on caffeine withdrawal and headaches.
Here is the abstrat, but they do not have period-specific outcomes.
Withdrawal syndrome after the double-blind cessation of caffeine consumption.
Source
Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21224.
Abstract
BACKGROUND:
People who stop consuming caffeine may have symptoms, but the incidence and severity of caffeine withdrawal are not known. This study was performed to determine the effects in the general population of ending one's dietary intake of caffeine.
METHODS:
We studied 62 normal adults whose intake of caffeine was low to moderate (mean amount, 235 mg--the equivalent of 2.5 cups of coffee--per day). They completed questionnaires about symptoms and tests of their mood and performance when consuming their normal diets (base-line period) and at the end of each of two two-day periods during which they consumed caffeine-free diets and under double-blind conditions received capsules containing placebo (placebo period) or caffeine (caffeine period) in amounts equal to their daily caffeine consumption.
RESULTS:
More subjects had abnormally high Beck Depression Inventory scores (11 percent), high scores on the trait scale of the State-Trait Anxiety Inventory (8 percent), low vigor scores (11 percent) and high fatigue scores (8 percent) on the Profile of Mood States, and moderate or severe headache (52 percent) during the placebo period than during either the base-line period (2, 0, 0, 0, and 2 percent, respectively; P less than 0.05) or the caffeine period (3, 2, 2, 0, and 6 percent; P less than 0.05). More subjects reported unauthorized use of medications during the placebo period (13 percent) than during the caffeine period (2 percent, P = 0.017). Performance of a tapping task was slower during the placebo period than during the base-line and caffeine periods (P less than 0.01).
CONCLUSIONS:
Persons who consume low or moderate amounts of caffeine may have a withdrawal syndrome after their daily consumption of caffeine ceases.
Comment in
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Jon Shuster
University of Florida
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Original Message:
Sent: 12-02-2011 11:29
From: Edwin Ndum
Subject: 2 Treatments, 2 Periods Clinical Trial Result (Binary Outcomes)
Thanks for the responses and the feedback. I really appreciate your suggestions.
Upon reading my post again, I believe my question was not accurately phrased. Sorry about that. But here is what I meant: I got a novel analysis of a 2x2 crossover design and I wish to test the estimates on a real data set. I must do this before I take it to my clients. I am looking for a real-world results of a clinical trial study, with binary outcomes - preferably explicitly stated in terms of number of subjects with a particular response.
Hope this is clearer.
Thanks Jon; Thanks Micheal; Thanks Jessica.
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Edwin NDUM, PhD
Research Associate, Statistical Research
ACT, Inc., Iowa City IA, USA
Tel: 319-341-2384 (W) 785-313-3803(C)
Fax: 319-341-2284 (W)
E-mail: ean_dong@yahoo.co.uk
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Original Message:
Sent: 12-02-2011 10:09
From: Michael Chernick
Subject: 2 Treatments, 2 Periods Clinical Trial Result (Binary Outcomes)
I am surprised that some of us have specific answers to the question. I have read the question many times and still do not understand what he was saying.
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Michael Chernick
Director of Biostatistical Services
Lankenau Institute for Medical Research
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