Introduction
In this paper, the article titled “Effect of 2-yn− 3 long-chain polyunsaturated fatty acid supplementations on cognitive function in older people: a randomized, double-blind, controlled” by Dangour et al., 2010 will be critically appraised. The article describes a study that sought to establish whether 2-yn− 3 long-chain polyunsaturated fatty acid supplementation has an effect on cognitive function in older people. In the study, a randomized, double-blind, controlled trial was used. Reduced cognitive function and dementia in older people continues to increase and pose a significant challenge to the elderly. Several studies have reported an association between the intakes of omega-3 long-chain polyunsaturated fatty acids (LC PUFAs) and docosahexaenoic acid (DHA), and improvement in cognitive function and a reduction in cases of dementia, especially among the older population. However, most of these studies employ observational designs. Therefore, they do not provide adequate evidence. Furthermore, there is no uniformity in various studies that have attempted to establish the effectiveness of fish oil in improving cognitive functioning. As a result, there is a knowledge gap in the effectiveness of fish oil in improving cognitive functioning. Therefore, this article seeks to address this knowledge gap. This review is intended to appraise the article to establish the quality of evidence presented in its findings.
Introduction Section
The relevance and quality of literature search used in the study is adequate. In this case, the article makes reference to studies dealing with omega-3 LC PUFA and DHA. The article acknowledges the benefits and roles of the two fatty acids in the body. The article also refers to studies that have been conducted to determine whether any cognitive benefit can be derived from omega-3 LC PUFA and DHA. In this case, the article acknowledges that most of such studies employed observational design. Consequently, the evidence provided by them is not sufficient to warrant the use of findings of such studies in making policies or influencing practice. In the article, Dangour and colleagues also refer to the findings of a recent randomized controlled trial. In this case, Dangour and colleagues report that in a recent randomized controlled trial in which 302 people participated, the participants did not report a statistically significant cognitive benefit following 400or 1800mg omega-3 LC PUFA supplementation. The literature search relied on whether the studies used employed experimental or observational design. The studies that employed observational design did not influence the current study as much as the studies that employed experimental design did.
The aims and hypothesis of the study are clearly stated in the article. In this case, the study was aimed at determining the cognitive benefits of omega-3 LC PUFA and DHA supplementation in elderly people. The hypothesis is stated as follows: n-3 LC PUFA supplementation can benefit cognitive function in cognitively healthy older people (Dangour et al., 2010). The hypothesis stated in the article is clear. Furthermore, it is based on observable and measurable things. For instance, cognitive benefits are measurable. However, the hypothesis could be improved further by stating the CVLT score required to reject or accept the hypothesis. The strength of the hypothesis is that it is empirically testable. Empirically testable hypothesis exhibit a high quality of evidence.
Methodology
Older people aged from 70 to 79 years old were the population of the study. The participants were selected using randomization technique. Randomization is an effective method for reducing bias that might occur during the selection exercise. The randomization conducted in the study was computer-based. The use of a computer in performing randomization further helped prevent bias. Since the selection methods used minimized bias, the selected participants can be said to be representatives of the entire target population. Bias was also minimized in the study by the use of a double-blind approach since the approach helps in decreasing chances of intentional bias by the people administering the intervention to either the active or placebo arm.
The study quality depends on the design used. The quality of design, on the other hand, depends on its ability to allow for the control of confounding variables. Designs that offer effective control of confounding variables are said to be of higher quality than designs that offer weaker control of confounding variables. The study described in the article is a randomized, double-blind, controlled clinical trial. Randomized controlled trails are highly recommended for clinical studies that seek to obtain evidence to inform health care practices. Controlled trials employ experimental designs to address study questions. Confounding variables are controlled more effectively in controlled trials than in studies that employ non-experimental designs. For instance, observational studies do not manipulate the independent variables in any way. Therefore, such studies provide low-quality evidence. Consequently, findings of such studies are not commonly used to inform health care practices or policies. The use of randomized controlled approach in this study is appropriate since it allowed for the control of various confounding variables.
The inclusion criteria used also helped in controlling the confounding variables. For example, individuals that reported the use of fish-oil supplements on a nearly daily basis were not eligible for enrollment in the study. If included, these individuals could have recorded different result from the rest of the participants. However, the findings of the study could not have been attributed to the intervention given. Therefore, it was necessary to prevent the influence of this confounding variable. Besides, participants whose scores in Mini-Mental State Examination (MMSE) were found to be less than 24 at baseline were excluded from the study. Such scores indicated that one is suffering from dementia or any other mental condition. Therefore, this inclusion criterion was appropriate in ensuring that the confounding variable is controlled. In general, adequate efforts were made during the exercise for recruiting participants to minimize bias. Furthermore, appropriate methods were used to control confounding variables. Control of the confounding variables has a positive effect on the quality of findings made from a study.
The sample size used in the study was appropriate and represented the target population. In this case, 13,834 participants were initially selected for enrollment in the study. This number was adequate since it made it possible for the researcher to obtain enough participants to be included in the analysis. Out of the initially selected number of participants, 376 were included in the analysis. This number is adequate considering the size of the target population. The study also observed the ethical obligations required in conducting studies involving human subjects. In this case, approval of the National Research Ethics Service was obtained before the commencement of the study. The London School of Hygiene and Tropical Medicine also gave approval for the study. All the participants also gave full, informed, and written consent before being enrolled in the study (Dangour et al., 2010).
The study had the control and the intervention group. The intervention given to the intervention group is clearly explained. In this case, the intervention group was given eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). On the other hand, the control group was given a placebo (capsule containing liver oil). The article provides an adequate description of the intervention given to all the groups involved. In this case, the article describes how the intervention was given and the roles played by different people in giving the interventions.
Results
The article reports the findings of the study comprehensively using different appropriate methods. There is a total of five tables displaying the results of the study: Table 1, Table 2, Table 3, Table 4, and Table 5. All the tables are clearly identified. For instance, Table 1 I clearly identified in the heading as such. The content of each table is also adequately described in their respective headings. For instance, the heading of Table 1 explains that the table contains the baseline data concerning the demographic, literacy, and health characteristics of the participants who took part in the study. The heading of Table 2 also indicates that the table contains data about the baseline characteristics concerning the cognitive function of the participants in the study. It is highly recommended for reports of studies to involve adequate description of all figures and tables used. Studies that present inadequate description of their findings are inadequate. The article also discusses the content of each table adequately. In addition, the deductions made from the information presented in the tables are adequately described.
The statistical analyses used in this study are appropriate. The study involved the use of various statistical analyses that helped in testing the hypotheses of the study. Each type of statistical analysis performed in the study was suitable for the purpose for which it was used. However, some analyses exhibit certain disadvantages. For instance, intention-to-treat (ITT) analysis was conducted in the study. This analysis is recommended for use in randomized controlled trials to minimize bias. In this analysis method, all participants that are already recruited and randomly assigned to either of the treatment groups are involved in the analysis regardless of whether they pull out of the study or they fail to adhere to the study protocols adequately. This method gives a more reliable estimate of the efficacy of a given treatment since it represents what happens in the real world. Additionally, the method preserves the sample size of the study. However, the assessment of the effectiveness of a given treatment method is not accurate in cases where this method is used. Despite this and other disadvantages, ITT is still recommended in randomized controlled studies.
Analysis of covariance (ANCOVA) was also used in the study. ANCOVA is used in studies that employ experimental designs to control for variables that are measurable on an interval scale but cannot be randomized. In this study, the method was used to adjust for covariance age, age at leaving full-time education, and sex. The method was also used in the adjustment for baseline cognitive function test scores (Dangour et al., 2010). The use of ANCOVA in the analysis in this study partly helped in achieving relatively more accurate results concerning the effectiveness of the treatments administered in both of the intervention arms. The article also quotes the confidence of interval. For example, in the primary analysis, the results were presented as appropriate effect sizes using a measure of the precision of 95% confidence level (CI) (Dangour et al., 2010). The study also used the appropriate software. In this case, STATA version 10 was used (Dangour et al., 2010).
The findings of the study are also adequately described in the article. The article describes all the study outcomes and offers explanations for them. In this case, both the primary and secondary outcomes are adequately described and explained. The California Verbal Learning Test (CVLT) served as the primary outcome of the study. In this case, both the baseline scores and the scores recorded at the end of the study of CVLT are presented and adequately described in the study. All the findings are presented in the tables and discussed further in the text. The authors of the article did not present any inappropriate generalization. Other studies that gave similar findings as the study are also described. Some clinical significance of the interventions given was discussed. For example, the article reports changes in the fat profile of the body of the participants recorded at the end of the study. However, the clinical significance is not reported to outweigh the statistical significance.
Conclusion
In general, the study meets all the scientific conditions need to be considered valid. The methodology of the study adequately minimizes the threats of internal and constructs validity. The overall quality of the study is high and meets the required level to be used in informing changes in health care practices. This study may also be used in making policies in the health care sector.
References
Dangour, A. D., Allen, E., Elbourne, D., Fasey, N., Fletcher, A. E., Hardy, P., & Uauy, R. (2010). Effect of 2-yn− 3 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: a randomized, double-blind, controlled trial. The American journal of clinical nutrition, 91(6), 1725-1732.
