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document
A six-month crossover chemoprevention clinical trial of tea in smokers and non-smokers : methodological issues in a feasibility study . BACKGROUND Chemoprevention crossover trials of tea can be more efficient than parallel designs but the attrition and compliance rates with such trials are unknown . METHODS Attrition ( dropouts ) and compliance with treatment were assessed in a 25-week randomized , placebo controlled , crossover , feasibility clinical trial of four tea treatments to investigate the effect of tea on oral cancer biomarkers . Each treatment lasted 4 weeks with 2 weeks of washout in between . Participants were 32 smokers and 33 non-smokers without any evidence of premalignant oral lesions . The interventions consisted of packets of green tea , black tea , caffeinated water , or placebo . Participants were assigned to each treatment for four weeks , and were instructed to drink five packets per day while on the treatment . Dropout from the trial and compliance ( consumption of ≥85 % of the prescribed treatment packets ) are the main outcome measures reported . RESULTS There was a high rate of dropout ( 51 % ) from the study , and the rates were significantly higher among smokers ( 64 % ) than non-smokers ( 36 % ) . Among participants who completed the study the rate of compliance was 72 % . The highest rates of dropouts occurred between the first and second treatment visits in both smokers ( 38 % dropout ) and non-smokers ( 18 % dropout ) . Throughout the study smokers were more likely to dropout than non-smokers . Black tea treatment was associated with the highest rates of dropout among smokers ( 37 % ) , but was associated with the lowest rate of dropout among non-smokers ( 4 % ) . CONCLUSIONS In a study conducted to test the feasibility of a four-treatment crossover tea trial , a high rate of dropout among smokers and non-smokers was observed . Multi-arm crossover tea trials might pose a higher burden on participants and research is needed to improve adherence and treatment compliance in such trials . TRIAL REGISTRATION NUMBER ISRCTN70410203 .
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Intervention_Physical
tea
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Intervention_Physical
four tea treatments
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Outcome_Other
Dropout
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Outcome_Mental
compliance
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Outcome_Other
high rate of
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Outcome_Mental
highest
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Outcome_Other
rates of dropouts
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Outcome_Other
rates of
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Participant_Condition
smokers
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Participant_Condition
non-smokers
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Participant_Sample-size
32 smokers and 33 non-smokers
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Participant_Condition
premalignant oral lesions