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. 2018 Apr 24;12:637-646.
doi: 10.2147/PPA.S158682. eCollection 2018.

Self-reported Adherence and Biomarker Levels of CoQ10 and Alpha-Tocopherol

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Free PMC article

Self-reported Adherence and Biomarker Levels of CoQ10 and Alpha-Tocopherol

Mara Z Vitolins et al. Patient Prefer Adherence. .
Free PMC article

Abstract

Purpose: Women with breast cancer were randomized to receive coenzyme Q10 (CoQ10) plus Vitamin E or placebo in a clinical trial. The objective of this evaluation is to examine the association between participant self-reported adherence to the study supplements and changes in plasma biomarker levels.

Patients and methods: Correlation coefficients quantified the association between changes in alpha-tocopherol and CoQ10 levels and the association between self-reported adherence and changes in biomarkers. Participants were categorized by self-reported adherence; Kruskal- Wallis tests compared changes in alpha-tocopherol and CoQ10 levels between self-reported adherence groups.

Results: Women (N=155) provided baseline and post-treatment biomarkers; 147 completed at least one diary. While changes in alpha-tocopherol and CoQ10 levels were moderately correlated, correlations ranged from 0.40 to 0.48, association between self-reported adherence and plasma alpha-tocopherol or CoQ10 levels was weak; correlations ranged from 0.10 to 0.29 at weeks 8, 16, and 24. Some participants with high self-reported adherence actually had decreases in their biomarker levels.

Conclusion: These findings support that self-reported adherence is likely to be overestimated. Biological and other measures of adherence that can better identify true adherence to study pills provided in clinical trials are greatly needed as they may assist in improving the interpretation of findings of future clinical trials.

Keywords: CoQ10; adherence; alpha-tocopherol; blood biomarkers; clinical trial; self-report.

Conflict of interest statement

Disclosure The authors report no conflicts of interest in this work.

Figures

Figure 1
Figure 1
Self-reported adherence at 8, 12, and 24 weeks for each adherence definition. Notes: Definition 1: excludes missing days; Definition 2: includes missing days in returned diaries as zeros; Definition 3: same as Definition 2 but also includes missing diaries as zeros.
Figure 2
Figure 2
Change in baseline in levels of CoQ10 and Alpha-Tochopherol at 8, 16, and 24 weeks.
Figure 3
Figure 3
Change in CoQ10 versus change in Alpha-Tochopherol at 8, 16 and 24 weeks in the CoQ10 intervention arm. Abbreviation: CoQ10, coenzyme Q10.
Figure 4
Figure 4
Change in Alpha-Tocopherol and CoQ10 versus self-reported adherence. Abbreviation: CoQ10, coenzyme Q10.

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