8 replies to this topic

[Nina]

The Superego Cafe team will regularly post an article to be critically appraised. Each article will be accompanied by questions that will form the learning points for that article. Answers will be posted a few days later.

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The article for Monday 24 October 2011 is:
Tanaka et al.: Occupational risk factors for Parkinson’s disease: a case-control study in Japan. BMC Neurology 2011 11:83.

Step 1

Download the article:
 criticalappraisal-com-journal-club-1471-2377-11-83.pdf   216.64K   44 downloads

Step 2

General question:
a) What is a case-control study design?

Questions about the article:
b) Comment on the selection of cases.
c) Comment on the selection of controls.
d) How well was the risk factor(s) defined?
e) What is the meaning of adjusted results?
f) Discuss the data shown in Table 1
g) Discuss the data shown in Table 2
h) Discuss the data shown in Table 3

If you wish to answer one of the above questions, please quote the question at the beginning of your reply. Feel free to discuss any aspect of the paper.

[koorosh]

a) What is a case-control study design?

Is analytic observational study.
It is start with a subject with the outcome variable at present and subject who do not have the outcome variable at present. compare this two group in retrospect to see what risk factor they have been exposed to .

Comment on the selection of cases.

multicenter hospital-based
cases were patients who were within 6 years of the onset of PD
diagnostic criteria: the United Kingdom Parkinson’s Disease Society Brain Bank
during the period from 1 April
2006 to 31 March 2008


c) Comment on the selection of controls.
Inpatient and outpatient from same centers with no previous diagnosis of neuro degenerative diseases
Not matched with the cases




d) How well was the risk factor(s) defined?

Known as Genetics and
environmental (like occupational exposures) as hypothesis. (Null hypothesis: there is no significant association between occupation and Parkinson’s disease)





f) Discuss the data shown in Table 1

Apart from smoking no significant difference between subjects and control present in term of age sex and educations
No P value generated to express the probability of this difference is by chance or is it statistically significant




g) Discuss the data shown in Table 2

All 95% CI encounter the range of odd ratio of 1 (unity).that revealed same outcome rates in two groups.
Though we can see :
Subjects working in protective service had 2.7 times more at risk of PD though it could be between risk being half or 14 times more in 95% of subjects which means this result as odd ratio is statistically and clinically is non significant.
For technical jobs it shows it has a protective measure as the od of having PD working in this group is almost half though it could be even third and up to minimal increase of the risk in 95% of time which again make it both statistically and clinically non significant.


h) Discuss the data shown in Table 3

All 95% CI are encounter the odds of 1 (unity),which revealed the estimates are not both statistically and clinically significant.
Though it shows working with occupation which have exposure to sand and stone can increase the odds to almost twice of developing PD. but we can conclude 95% it can be reducing the risk to almost third and increase the odds up to almost 11 time.

[Nina]

@koorosh Thank you for your contribution! We'll be posting our answers in a couple of days. Everyone else is welcome to post their answer(s) or comment(s) about the paper.

[Nina]

Attached document contains answers to the questions.
 criticalappraisal-com-journal-club-1471-2377-11-83qa.pdf   154K   34 downloads

PowerPoint presentation to follow.

[koorosh]

can not download the power point !

[slee]

Nina, just had a go at appraising the article. Had a look at Koorosh's answers and yours afterwards....so helpful! Thanks!

[Nina]

A PowerPoint presentation of the critical appraisal is available - click here

Access to this file requires an active subscription to the Critical Appraisal Online Course. Subscriptions are included with reservations on the Critical Appraisal One Day Course, Critical Appraisal Two Day Workshop and Critical Appraisal Bespoke Course.

[Nina]

slee, on 28 Oct 2011 - 10:12, said:

Nina, just had a go at appraising the article. Had a look at Koorosh's answers and yours afterwards....so helpful! Thanks!

Thanks for the feedback! All feedback is gratefully received!

We'll be developing the Journal Club taking into account all the comments we receive. I think over the next few weeks the Journal Club will settle into a consistent format. Over time we hope to cover all aspects of critical appraisal using a selection of clinical papers. We're not aiming to teach and discuss every aspect of every paper, although we're happy to reply to any posts made by forum members. As long as you learn something from every paper, that will be fine!

[Chantal]

Dear Nina,

Thank you for posting the answers. I found it was a great way to help cement the knowledge I gained from the two day workshop.

Many thanks,
Chantal