VET656: Article Critique of Sleep, Breast Cancer Risk in Australia

This report is a critical appraisal of a research article titled "Self-reported sleep duration, sleep quality, and breast cancer risk in a population-based case-control study (2013)" by Girschik et al. The critique evaluates the study's methodology, including the title and abstract, introduction, materials and methods, results, and discussion and conclusion, in accordance with the STROBE guidelines. The study investigated the association between sleep duration and quality with breast cancer risk. The report highlights strengths such as the logical structure and clear presentation of sections, along with weaknesses like inconsistencies in presenting dates and the lack of hypothetical statements in the introduction. The critique also examines the study design, statistical methods, and results reporting, including the use of odds ratios and logistic regression. The report also discusses confounding factors like menopause, and the study's conclusions regarding the lack of a significant relationship between sleep and breast cancer. The critique concludes with an evaluation of the references and acknowledgements, assessing the overall value and contribution of the research.

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Article Critique
Self-reported sleep duration, sleep quality, and breast cancer risk in a population-based
case-control study (2013)
By: Jennifer Girschik, Jane Heyworth, Lin Fritschi
1. Description
Breast cancer is the number one invasive cancer and cause of death among women in
Australia and across the world. Various studies have attempted to establish the risk factors for
this condition, but those only account for a minuscule proportion of the total cases. Increased
efforts to deduce more risk factors led to the need to a certain the role of sleep due to the
reduction in sleep duration and quality in the recent times. Thereby, the current study south]
The study was guided by two hypothesis as indicated below, even though they have not been
indicated by the authors.
1. There is no association between sleep quality and breast cancer.
2. There is no association between sleep duration and breast cancer.
A population-based case-control study was carried out but the paper has some inconsistencies
in the presentation of ideas. For example, after reading the abstract, there is the insinuation
that the study was conducted between 2009 and 2011. However, after getting to the methods’
section, the actual dates of the study are not given and the duration inferred to in the abstract
refers to the times when the participants included in the study were diagnosed with the
specified condition of interest. Otherwise, the paper is free of typological and grammatical
errors. All the same, the research paper is constructed in a logical manner and all the different
sections are clearly indicated (1).
Article Critique
The article was critiqued as guided by the questions provided for this assessment, from which
the STROBE guidelines are developed (2, 3).

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2.1 Title and Abstract
Both the title and abstract are good synopses of the research study paper. The title includes
the study’s aim and research design; however, it would have been more comprehensive if it
mentioned the study population. The abstract is a well-detailed summary of the entire study.
The abstract highlights the research gap leading to the purpose of the study, study design and
associated data collection methods, results, and a succinct conclusion. Thereby, by just
reading the abstract, one can understand what the study is about, for whom it was done, and
how it was one. However, it would have been more informative if it provided relevant
recommendations. The inclusion of keywords enhanced the abstract, and it was easy to relate
them to the study because they are relevant. Important keywords including, sleep, sleep
duration, sleep quality, case-control studies, and breast cancer formed part of the keywords.
2.2 Introduction
The introduction has been well-developed as it begins by giving a clear background about the
nature of breast cancer while referring to the population of interest: women, in both the study
setting and the larger universe. The introduction mentions the input from previous research
studies and their inadequacies, giving rise to the current research gap. In the introduction, the
risk factors of interest have been introduced and the rationale for their selection in the current
study provided. The literature that has been used in the introduction is relevant because it
consists of research studies carried out in the past focusing on the seemingly risk factors of
interest. However, sleep-related factors are not the main focus because as seen in the
method’s section, the main hypothetical statement is in reference to exposure to shift work.
Thereby, there is some incongruence between the main research goal and the risk factors
reviewed in the introduction. After reading the introduction, one believes that the study’s
focus is on sleep duration and quality, while in actual sense, this is not the focus. The

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introduction indicates the originality of the study as it seeks to determine whether sleep
duration and quality are risk factors for breast cancer using a primary research approach.
The introduction is flowing in a logical manner beginning with a description of breast
cancer and the current knowledge of risk factors linked to the condition. In the introduction,
the aftermath of poor sleep and underlying biological models have been integrated and winds
up with a strong rationale for conducting the study before introducing the purpose of the
study as the last thing. However, the introduction would have been better if it would have
included hypothetical statements for testing considering that breast cancer is linked to three
domains: sleep duration on workdays, sleep duration on nonworkdays, and subjective sleep
quality (4).
2.3 Materials and Methods
Erdemir (5) indicates that the materials and methods of a research study should highlight the
dates when a study was conducted, the number of study participants, ethical approval, and
study design. Guided by the critiquing questions for this assessment unit, the study’s design
and associated methodology, sampling and sample size in reference to matching the cases and
the controls, data collection procedure and associated instruments, ethical review, and
application of statistical tests should be well explained.
The study design used is appropriate for the current study that sought to determine the risk
factors because both the cases and controls were asked to fill the same questionnaire
evaluating exposure to the disease-causing agents. LaMorte (6) notes that case-control studies
are ideal for determining the risk factors of conditions. The study is articulate about the
individuals that were included in the study based on the time of diagnosis with breast cancer,
precisely invasive breast cancer. Ethical approval was sought from the Western Australian
Department of Health and the University of Western Australia, but the reason for seeking the

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approval is not given. Also, informed consent was obtained from the study participants and
forms a basis for inclusion of the study participants in the final sample size.
In reference to the STROBE guidelines that are part of the critique questions provided for this
assessment, matching the cases to the controls should be done well to represent the study
populations (3). Whereas the sample seemingly represent the study populations from which
they are drawn, it does not seem plausible that half of the women population has breast
cancer based on 1000 cases versus 2000 control, as per the calculated sample sizes. Also,
there is no explanation why the calculated sample size is different from the samples that were
eligible for inclusion in the study. Contrary to 1000 cases, 2089 were eligible while 4358
controls were eligible. Nonetheless, the response rate was low as most of the individuals
refused to participate, others did not respond, and some died. Nonetheless, based on the
calculated sample size, it seems that the researchers addressed the low response rate by
recruiting a large proportion of eligible cases and controls. Thereby, the breakdown of the
sample size is not clear. Both the cases and controls were treated equally as seen by the fact
that the same measurement scales were used for both the cases and controls.
Unfortunately a pilot was not performed in the current study. A pilot study is deemed
imperative for a research because it helps researchers to anticipate the success and drawbacks
of a research (7). Like in the case of the low response rate where a certain pattern was
established, a pilot study helps to develop solutions for such anticipated drawbacks that are
likely to present when conducting the main research. Inclusion and exclusion criteria were
used, and these can be considered to be strategies for minimizing bias, which is a strength for
the study (8). In the current study, three elements were used as exclusion criteria to help
generate accurate responses for the specified cancer type: invasive breast cancer.
2.3.2 Study Design

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The study’s design was elaborate. Even though no specific measures were used, it is easy to
understand the variables that were of interest. The main shortcoming of the study design is
that it fails to justify some of the procedures used. In the case of matching the cases and
controls, the study design would have been more credible if it highlighted the study
populations from which the samples were drawn. Also, the reason for developing the
exclusion criteria needed to be explained because compared to the rationale of developing
these criteria, some of the criteria included are not clear.
The research has not indicated how the testing of the data collection instruments was done;
hence, the validity and reliability of the data collection questionnaire is not guaranteed (9). A
self-administered questionnaire was used, which could explain why individuals that did not
have a good comprehension of the English were excluded. As a result, the study did not use
research assistants and did no trainings were needed. However, the exclusion of those
diagnosed 6 months prior to the notification made to the Western Australian Cancer Registry,
is not clear.
2.3.3 Statistical Methods
The statistical tests used were appropriate for the purpose of the study. Odds ratios and
logistic regression were used to determine the risk factors. Rizzo and others (10) indicate that
these tests are appropriate when establishing the risk factors of disease (s). Another major
strength of the research study is its ability to identify and account for confounding factors.
Both probable and possible confounding factors were identified and their contribution to the
ultimate multivariable effect determined.
2.4 Results
The study’s results are the most paramount sphere to the STROBE guidelines. These
guidelines focus on determining the validity of the results based on the formulation of study
goals, selection of study design, recruitment of study participants, and measurement of

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exposure in relation to recall bias, confounding factors, treatment of the study groups, and the
precision and magnitude of the results. The current study main research goal has been
overtaken by the focus on sleep quality and sleep duration. The study has strong points in
addressing most of these elements highlighted in the critiquing tools to ensure the results are
credible. The numbers for the results have been well represented in relation to both
descriptive ad inferential statistics. Percentages have been used to describe phenomenon
while odds ratios have been used to identify the risk factors.
The study does not indicate the final sample used, and this is a downside of the paper.
Nonetheless, the results have been explained in reference to the general population for the
various variables under study. The cases have been well defined in reference to their socio-
demographic and economic statuses. Tables have been used to enhance presentation of the
results. The results were complex as they were not limited to the study variables only. Socio-
demographic and economic characteristics of the sample population helped to understand the
association of the variables better and form basis for future researches. The results are
believable because the study followed the paramount aspects making up a valid study.
Reporting of the results has been done in relation to the statistical tests used, for example the
odds ratios and stratified analysis (form of logistic regression) when focusing on more than
on risk factor. The results were not statistically significant but are clinically significant
because they help to refine practice and eliminate the assumptions made on the influence of
poor quality sleep in causing chronic illness.
2.5 Discussion and Conclusion
The discussion discusses the results and factors in major confounding factors like menopause
and associated estrogen receptor status because women as young as 18 years and as old as 80
years were part of the study participants. The strengths and weaknesses of the study have
been explained, and a noticeable aspect is the poor explanation and inconsistency of data

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collection instruments. In the methods section, there is no indication that a pretest was done
for the data collection instruments, but this is indicated in the discussion. The findings have
been critiqued based on the different risk factors, both primary and secondary. The findings
re discussed based on the risk factors of interest and associated probable and possible
confounding factors. The conclusion is succinct indicating that there is no relationship
between sleep duration and breast cancer as well as sleep quality and breast cancer.
2.6 References and Acknowledgements
The study was carried out in 2013 and the fact that references as old as 1980 are included
means that the researchers did not place much emphasis on up-to-date references. However,
the sources are relevant based on the sphere they have been used to explain or justify. Even
though there are is no conflict of interest, the people and organizations that supported
development of the research work have been mentioned and given the credit they deserve.
3. Over Assessment and Conclusion
3.1 Strengths and Weaknesses
a. The research article has adhered to most of the guidelines used to critique a case-control
study.
b. The research article articulately highlights the research gap leading to the research study’s
purpose.
c. The introduction is well written and organized.
d. The study design used is suitable in determining the risk factors of a particular condition.
e. The confounding factors have been factored in with the aim to minimize bias.
f. The results were well-explained and tables were used to enhance the explanations.
g. Results have been discussed while inferring to previous studies.
3.2 Weaknesses

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a. The research gap is not the study’s main focus, which is exposure to shift work as a risk
factor for breast cancer. In reference to work shift, one would have expected to see
discussions in duration of work hours and type of work rather than sleep duration and sleep
quality.
b. Sample size determination and the final sample size used have not been well explained.
c. The data collection instruments were not pretested and the protocol of calculating and
getting the final sample size is missing.
d. Credibility of results affected by recall bias and selection bias, where the latter is attributed
to low response rate.
In view of the fact that the main hypothesis was work shift, future studies should focus on
measures of work shift in relation to breast cancer, for example number of hours spent in the
workplace, time of reporting, and time of leaving.
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