Related Experiment Video
Updated: Jan 31, 2026
05:42
An Assessment Method and Toolkit to Evaluate Keyboard Design on Smartphones
Published on: October 5, 2020
3.7K
Extreme restriction design as a method for reducing confounding by indication in pharmacoepidemiologic research
Matthew H Secrest1, Robert W Platt1,2,3, Colin R Dormuth4
1Centre for Clinical Epidemiology, Lady Davis Research Institute, Jewish General Hospital, McGill University, Montreal, Canada.
Pharmacoepidemiology and Drug Safety
|January 11, 2019
Summary
Extreme restriction in pharmacoepidemiologic studies effectively reduces confounding by indication. This method, applied to proton pump inhibitor use and pneumonia risk, removed an apparent association, highlighting its utility in observational research.
Area of Science:
- Pharmacoepidemiology
- Observational Study Design
- Biostatistics
Background:
- Confounding by indication is a significant challenge in observational pharmacoepidemiologic studies, particularly those employing active comparator, new user (ACNU) designs.
- This bias can distort the true drug effect by mixing indication-related factors with treatment effects.
- Existing study designs require refinement to mitigate this pervasive issue.
Purpose of the Study:
- To introduce and evaluate a novel method, termed "extreme restriction," for reducing confounding by indication in observational studies.
- To assess the impact of this restriction method on the association between proton pump inhibitor (PPI) use and hospitalization for community-acquired pneumonia (HCAP).
- To compare the effectiveness of the extreme restriction method against the standard ACNU design in controlling for confounding.
Main Methods:
- A case study was conducted using the UK's Clinical Practice Research Datalink to examine PPIs and HCAP risk.
- An active comparator, new user (ACNU) cohort was analyzed using Cox proportional hazard models, comparing PPI users to histamine-2 receptor antagonist (H2RA) users.
- An "extremely-restricted" cohort of incident nonsteroidal anti-inflammatory drug (NSAID) users, receiving PPIs for prophylaxis, was analyzed to limit confounding by indication (e.g., gastroesophageal reflux disease).
Main Results:
- In the ACNU cohort, PPI use was associated with an increased risk of HCAP (Hazard Ratio [HR]: 1.25; 95% Confidence Interval [CI]: 1.05, 1.47).
- In the extremely-restricted cohort, this association between PPIs and HCAP was no longer statistically significant (HR: 1.06; 95% CI: 0.75, 1.49).
- The comparison demonstrated a substantial reduction in confounding by indication in the restricted cohort.
Conclusions:
- Restriction to a single indication, or "extreme restriction," is a viable strategy to reduce confounding by indication in pharmacoepidemiologic research.
- This method can improve the accuracy of effect estimates in large databases and distributed data networks.
- Extreme restriction offers a valuable tool for strengthening the validity of observational drug safety and effectiveness studies.
Related Concept Videos
02:39Indicators
60.6K
Certain organic substances change color in dilute solution when the hydronium ion concentration reaches a particular value. For example, phenolphthalein is a colorless substance in any aqueous solution with a hydronium ion concentration greater than 5.0 × 10−9 M (pH < 8.3). In more basic solutions where the hydronium ion concentration is less than 5.0 × 10−9 M (pH > 8.3), it is red or pink. Substances such as phenolphthalein, which can be used to determine the pH of a solution, are...
60.6K
01:22Methods of reducing fever
1.4K
The signs and symptoms of fever include hot and dry skin, flushed face, thirst, muscle aches, anorexia, headache, tachycardia, tachypnea, and fatigue. Elevated body temperature is reduced using two methods: pharmacological and nonpharmacological. Proper identification and treatment of the root cause of a fever is of utmost importance.
Pharmacological Methods of Reducing Fever:
Pharmacological Methods of Reducing Fever:
1.4K
02:01Group Design
10.4K
The most basic experimental design involves two groups: the experimental group and the control group. The two groups are designed to be the same except for one difference— experimental manipulation. The experimental group gets the experimental manipulation—that is, the treatment or variable being tested—and the control group does not. Since experimental manipulation is the only difference between the experimental and control groups, we can be sure that any differences between...
10.4K
01:27Confounding in Epidemiological Studies
802
Confounding in statistical epidemiology represents a pivotal challenge, referring to the distortion in the perceived relationship between an exposure and an outcome due to the presence of a third variable, known as a confounder. This variable is associated with both the exposure and the outcome but is not a direct link in their causal chain. Its presence can lead to erroneous interpretations of the exposure's effect, either exaggerating or underestimating the true association. This...
802
01:25Strategies for Assessing and Addressing Confounding
395
Confounding is a critical issue in epidemiological studies, often leading to misleading conclusions about associations between exposures and outcomes. It occurs when the relationship between the exposure and the outcome is mixed with the effects of other factors that influence the outcome. Given that, addressing confounding is of high importance for drawing accurate inferences in research.
Confounding can be addressed at both the design phase of a study and through analytical methods after data...
Confounding can be addressed at both the design phase of a study and through analytical methods after data...
395
01:11Restriction Enzymes
36.0K
Restriction enzymes are bacterial enzymes used to cut DNA in a sequence-specific manner. To cleave DNA, they bind to specific palindromic sequences called restriction sites. Such palindromic DNA sequences or inverted repeats are commonly found in regions of functional significance, such as the origin of replication, gene operator sites, and regions containing transcription termination signals.
The host bacteria protect their own genomic DNA from these enzymes by methylating these sites. Some...
The host bacteria protect their own genomic DNA from these enzymes by methylating these sites. Some...
36.0K