Review Question - QID 210435

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Bias Types of Bias Types of Bias Bias Description Mitigation Accumulation Effect patients sometimes must be exposed to a risk factor for a prolonged period of time before they develop a clinically detectable result e.g., patients must smoke for many QID: 210435 (M2.OMB.18.1)

QID 210435 (Type "210435" in App Search)

A pharmaceutical company conducts a randomized clinical trial in an attempt to show that their new anticoagulant drug prevents more thrombotic events following total knee arthroplasty than the current standard of care. However, a significant number of patients are lost to follow-up or fail to complete treatment according to the study arm to which they were assigned. Several patients in the novel drug arm are also switched at a later time to a novel anticoagulant or warfarin per their primary care physician. All patients enrolled in the study are subsequently analyzed based on the initial group they were assigned to and there is a significant improvement in outcome of the new drug. What analysis most appropriately describes this trial?

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As treated

11%

2/19

Intention to treat

68%

13/19

Modified intention to treat

16%

3/19

Non-inferiority

1/19

Per protocol

0/19

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This study is analyzing individuals based on the group they are randomized into rather than the treatment they received or adherence to treatment. This is an intention to treat analysis.

In an ideal setting, all subjects enrolled in a research trial would complete the trial exactly as prescribed in the protocol. However, this ideal is rarely achieved, and thus trial design and data analysis must account for incomplete adherence and follow-up. Intention to treat analysis, in which subject results are analyzed according to the group that they were initially assigned to (not according to adherence) is one technique used to analyze outcome data and preserve randomization. This method is a more reliable estimate of the true treatment effectiveness clinically by replicating what happens in the 'real world.' In addition, it also prevents bias as all randomized subject are included an analyzed rather than being excluded in a potential non-random fashion. Drawbacks of this study design are it may understate the treatment effect given non-compliance.

Incorrect Answers:
Answer 1: As treated analysis analyzes individuals on the treatment that they actually received rather than the treatment they were assigned to. This study design is subject to confounding.

Answer 3: Modified intention to treat analysis allows the exclusion of some of the randomized subjects from the study if there is a justifiable reason to exclude them. The problem with this analysis is the "justifiable" reasons to exclude someone may represent bias and subsequently influence the data.

Answer 4: Non-inferiority trials test whether a new treatment is less effective than the current standard of care. This study design was rather attempting to demonstrate superiority.

Answer 5: Per protocol analysis only includes patients who followed the treatment/intervention as intended in the study protocol. The benefit of this study design is it shows the real treatment effect of the drug. The drawback is that it may less reflect what occurs clinically given that adherence is not perfect in normal clinical scenarios.

Bullet Summary:
Intention to treat studies analyze participants based on the group they are randomized into regardless of any deviations from the protocol.

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