Quiz 7 Flashcards
Q1 If a study reports a participant outcome as either being alive or deceased, what type of data is being assessed?
a) Ordinal
b) Qualitative
c) Continuous
d) Dichotomous
d) Dichotomous
More: review the resources form weeks 3-4 for more information
A study was completed for symptoms and physical findings in 247 patients evaluated for sinusitis. The finial diagnosis was made according to x-ray findings (gold standard). Facial pain had a sensitivity of 52%. Select the response below that most accurately describes this result.
a) 52% of patients without sinusitis (gold standard) presented without facial pain
b) 52% of patients with sinusitis (gold standard) presented with facial pain
c) When a highly specific test is used, a negative results tends to rule in the disorder
b) 52% of patients with sinusitis (gold standard) presented with facial pain
More: review the resources from week 6 for more information on this topic (diagnostics)
A randomized controlled trial compares two common drugs used to treat asthma patients. In the paper the authors stat that “an intention to treat analysis” was undertaken. Select the statement below that outlines an advantage of this method.
a) It describes the effects of the treatments that the patients have actually received
b) It is unlikely to underestimate treatment effect
c) It is not affected by patients dropping out of the study
d) If preserves randomization – irrespective of whether the patients took the medications or not.
d) If preserves randomization – irrespective of whether the patients took the medications or not.
More: review the intervention chapter from the textbook and weeks 3-4 notes / readings for more information
Which of the following is the main advantage of RCTs over observational studies of treatment effect?
a) Prevention of confounding
b) Less expensive
c) Fewer ethical issues
d) Quicker answers
a) Prevention of confounding
More: RCTs assist in the prevention / minimization of the impact of confounding on the study results. Review the notes from week 3 and 4 for more information.
Access this article: Doi 10.111/j.1708-8305.2007.00144.x or search “loperamide plus azithromycin more effectively treats travelers’ Diarrhea in Mexico than azithromycin alone”. Read the article above and answer the following questions:
1) Was the assignment of participants randomized?
2) Was allocation concealed?
3) Were the groups similar at the start?
4) Were participants blind to which study group they were in?
5) Were health professionals who provided the intervention blind to participants’ study group?
6) Were the assessors blind to participants’ study group?
7) Were all participants who entered the trial properly accounted for at its conclusion, and how complete was the follow up?
8) Was an intention-to-treat analysis used?
9) Did the study have enough participants to minimise the play of chance?
1) Was the assignment of participants randomized?
Yes, participants were randomly allocated. Medications were randomized in blocks of 12 participants.
2) Was allocation concealed?
Cannot tell. It is not clear if concealed allocation has occurred.
3) Were the groups similar at the start?
Yes, there were no clinically important differences in demographic characteristics or clinical features of illness between the three study groups at enrolment.
4) Were participants blind to which study group they were in?
Yes, the use of the double dummy technique should have ensured this occurred. This means that the medications could not be made to look identical, so an extra set was made. This meant that all participants took two types of tablets or capsules.
5) Were health professionals who provided the intervention blind to participants’ study group?
Cannot tell. The article does not explicitly state that the health professionals who provided the medication were blind to participant group allocation. Although the methods section states that a double dummy technique used that the study was double blind, it is not clear of the ‘double’ part of the blinding is referring to the health professionals or the assessors (and of course participants).
6) Were the assessors blind to participants’ study group?
Yes. As the main outcomes were self-reported and participants were blind to group allocation, the participants were actually the assessors.
7) Were all participants who entered the trial properly accounted for at its conclusion, and how complete was the follow up?
Yes. Only 14 participants dropped out, giving a follow-up rate of 91%. Reasons were given for loss to follow-up as well as which group they were in.
8) Was an intention-to-treat analysis used?
Yes. It explicitly states that an intention to treat analysis was conducted.
9) Did the study have enough participants to minimise the play of chance?
A power calculation was presented in which sample sizes permitted detection of diarrhea from over 24hours to less than 12hours in a three-way comparison at a power of 0.8. Overall this paper has a solid methodology, therefore you would expect the result to be valid.
After completing a study the authors report that the positive likelihood ratio for their new diagnostic test is ‘12’ and conclude that the test is extremely good for ruling in disease.
a) True
b) False
a) True
More: review the resources from week 6 for more information on this topic.
Briefly outline why a retrospective cohort prognosis study is lower in the hierarchy then a prospective cohort prognosis study. 1-2 sentences.
More: a retrospective cohort study is more likely to have recruitment bias and it is quite common to systematically miss patients with particular characteristics.
The best study design for prognosis evidence is a prospective _________ cohort study.
More: ‘inception’ cohort study. See week 7 resources for details on this topic.
