Study: Coenzyme Q10: An Independant Predictor of Mortality in Chronic Heart Failure

Aim: To investigate the relationship between plasma coenzyme Q10 (CoQ10) and survival in patients with chronic heart failure (CHF).

DOI: 0.1016/j.jacc.2008.07.044

Abstract, title and references:

The aim clearly defines what the study intends to review. The study revealed that CoQ10 deficiencies are an independent predictor of mortality from heart failure in this cohort study. The concise background, results and conclusion were clearly defined and easy to read. The title states the findings and the aim of the research in the body of the paper. There were 34 well documented references that were used throughout the study to support the findings and information. There were a few older studies dating back to 1957, but the majority of the studies sited dated from 2000-present. Researchers did a great job referencing and finding appropriate past literature to support the study.

Introduction and background:

Scientists discussed past literature on total cholesterol and the incidence of heart failure. The clearly stated the gap in literature in relating CoQ10 levels in patients with heart failure and intended to study the prediction of heart failure and mortality in patients with low CoQ10 levels. In their review of literature, researchers found several studies on CoQ10 and heart failure but none that specifically related a risk of serum concentration to HF risk prediction. Many of the key studies were listed, although in my opinion some studies were missed in the review. That may have been due to the vast amount of literature present on CoQ10.

Methods:

This was a cohort study with data collected between 2000-2004. Patients were recruited upon admission to the hospital with symptomatic coronary heart failure (CHF). A total of 3,576 were screened and 998 met criteria and 236 patients were enrolled. The study lacked a detailed table that described the exclusion methods used in this study. High quality methods of measuring COQ10 levels and cholesterol markers were used in the study. Statistical analysis of the labs measured were accurately displayed on a table that was easy to read and evaluate. The methods of the study were valid and reliable, but it lacked the details on the methods section to fully replicate the study.

Results:

The tables and graphs presented in this study were the strongest part giving the reader clear results and very specific markers with appropriate P values and numbers that are easily reviewed and interpreted. The titles, columns and rounding of numbers and details were precise and marked for easy read. The text associated with the results was not repetitive and they gave meaningful data so the reader could clearly understand its significance. They clearly defined the values that were significant in survival rates in CHF patients.

Discussion and Conclusions:

The first paragraph briefly described the results and then the discussion went on to further explain the results in more detail. They added figure 2 which showed the appropriate P values in a graph, so readers could see the survival rates more clearly. Scientists did a nice job of stating the correlations in lab values in the discussion section that described how they came to the ultimate conclusions about predicted survival rates and COQ10 levels. The conclusion was short and to the point summarizing the discussion section in a few sentences, so readers could quickly see the results.

Overall:

The study design was appropriate for the aim of this research. Scientists were able to find the correlation between CoQ10 levels alone and an increased risk of heart failure in patients. While we knew from past studies there was some correlation, this one proved the relation of CoQ10 without other factors like high total cholesterol and an increase in mortality in heart failure patients. The only flaw to the study was the detail section on the methods area. More details about the study could have been given to properly replicate this in many populations of patients. The article was consistent in its findings and well written so it can be easily interpreted.

Overall Statement:

This article isolated CoQ10 as an independent risk factor of mortality in patients with CHF. Scientists were able to assess other risk factors such as cholesterol and NT-proBNP and provide statistical values to support the idea that CoQ10 deficiency alone increases the risk for mortality in patients with CHF.

Strengths of the study:

The strengths of the study were the following: 1. The study provided a very thorough table with clearly sited results from the lab results that is easy to review and evaluate by the reader. 2. The results section was detailed and clearly defined the significance of the values found in the study. 3. The discussion section was detailed and very easy to follow with the graphs that showed the mortality risk and CoQ10 as well as other lab values taken. Readers can easily understand the details of the results and interpret them in a useful way.

Weaknesses:

Major points in the article which needs clarification, refinement, reanalysis, rewrites and/or additional information and suggestions for what could be done to improve the article.
1. The methods section could provide more details about the study, so the design could be more easily replicated.

1. Limitations to the study were not clearly defined. A paragraph discussing any limitations should be added.

2. The conclusion section should detail the suggested further research. While there was a short sentence, the suggested research is not clear. “and there is a rationale for further controlled intervention studies of CoQ 10 supplementation.”

Minor points like figures/tables not being mentioned in the text, a missing reference, typos, and other inconsistencies.

1. A more detailed view of how the researcher excluded study participants should be added so readers can review the criteria more closely.

2. Otherwise, there were no visible inconsistencies, missing references or major typos.