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Drug for Rheumatoid Arthritis Read the portion of the abstract of a scientific study that appears below, and then answer the questions that follow. "Methods: In this ... double-blind, placebo-controlled ... study, 611 patients were randomly assigned, in a \(4: 4: 1\) ratio, to [receive] \(5 \mathrm{mg}\) of tofacitinib twice daily, \(10 \mathrm{mg}\) of tofacitinib twice daily, or placebo. The primary end point, assessed at month 3, was the percentage of patients with at least a \(20 \%\) improvement on the American College of Rheumatology scale (ACR 20 ), Results: At month 3 , a higher percentage of patients in the tofacitinib groups than in the placebo groups met the criteria for an ACR 20 response \((59.8 \%\) in the \(5-\mathrm{mg}\) tofacitinib group and \(65.7 \%\) in the \(10-\mathrm{mg}\) tofacitinib group vs. \(26.7 \%\) in the placebo group, \(\mathrm{P}<0.001\) for both comparisons)." a. Identify the treatment variable and the response variable. b. Was this a controlled experiment or an observational study? Explain. c. Do the sample percentages suggest that the drug was effective in achieving a \(20 \%\) reduction in symptoms? d. What does the small p-value show? c. Can you conclude that the use of tofacitinib increases the chances of a \(20 \%\) improvement in symptoms? Why or why not?

Step by step solution

01

Identify the treatment and response variables

The treatment variable is the type and dose of medication the patients receive - either \(5 \mathrm{mg}\) of tofacitinib, \(10 \mathrm{mg}\) of tofacitinib, or a placebo. The response variable is the percentage of patients with at least a \(20 \%\) improvement on the American College of Rheumatology scale (ACR 20 ).

02

Assess the type of the study

This is a controlled experiment, not an observational study. This is because the researchers are actively manipulating the variable (the type and dose of medication given) and evaluating the effect on the response variable, which is the patient's improvement.

03

Analyze the effectiveness of the drug

The percentages of patients with at least a \(20 \%\) reduction in symptoms in the tofacitinib groups (\(59.8 \%\) for the \(5\)-mg group and \(65.7 \%\) for the \(10\)-mg group) are significantly higher than in the placebo group (\(26.7 \%\)). This suggests that the drug was indeed effective in achieving a \(20 \%\) reduction in symptoms.

04

Understand the significance of the p-value

The small p-value (\(P < 0.001\)) indicates that the difference in percentages is statistically significant. This means that the probability that the results occurred by chance is less than 0.1 percent.

05

Conclude from the results

Given the significant statistical results (\(P < 0.001\)) and the large percentage of patients who improved in the tofacitinib groups, it is reasonable to conclude that the use of tofacitinib increases the chances of a \(20 \%\) improvement in symptoms. However, this conclusion can only be applied to the studied population and in the context of the study - more research would be needed to generalize the conclusion.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Treatment Variable

In a controlled experiment, such as the study of tofacitinib for treating rheumatoid arthritis, the treatment variable is crucial. Here, the treatment variable is the type and dose of medication administered. Patients were divided into groups receiving either 5 mg or 10 mg of tofacitinib twice daily, or a placebo.

This variable is what researchers manipulate to observe changes in the study. It is essential that the treatment variable is clearly defined to ensure the results are attributable to specific treatments administered.

• This separation allows investigators to assess the direct impact of the treatment.
• It distinguishes between different treatment effects and a control group (placebo).

By doing so, researchers can measure how well the drug performs compared to no treatment (placebo), directly observing the treatment's effects.

Response Variable

The response variable is the outcome that researchers measure to determine the impact of the treatment. In the study on tofacitinib, the response variable is the percentage of patients achieving at least a 20% improvement on the American College of Rheumatology scale (ACR 20).

This scale measures the severity of rheumatoid arthritis symptoms and indicates patient improvement in response to treatment.

• This quantitative measure allows researchers to compare the treatment effects.
• It highlights the difference between those receiving the drug versus a placebo.

By focusing on the response variable, the study aims to objectively measure the drug's efficacy in alleviating symptoms of rheumatoid arthritis.

Statistical Significance

Statistical significance is a key concept in determining whether the results of an experiment are likely due to chance. In the context of the study, the p-value was less than 0.001, indicating strong statistical significance.

What does this really mean? A low p-value suggests that the likelihood of observing the difference in improvement rates purely by random chance is less than 0.1%.

• This implies the results are highly reliable and not likely attributable to random variations.
• It corroborates the conclusion that the medication had a true effect.

By establishing statistical significance, researchers can confidently assert that the treatment had a measurable impact compared to the placebo, reinforcing the study's validity.

Drug Efficacy

Drug efficacy refers to the ability of a treatment to produce the desired therapeutic outcome. In this study of tofacitinib, the drug's efficacy is reflected in the higher percentage of patients experiencing a 20% improvement in symptoms compared to the placebo group.

Such outcomes demonstrate that tofacitinib has a significant therapeutic effect, making it a potentially effective treatment for rheumatoid arthritis sufferers.

• The comparison between treatment and placebo groups offers insights into actual drug performance.
• Higher improvement rates in the drug groups confirm its potential benefits.

Understanding drug efficacy is vital for deciding on new treatments and validating their use in medical practice. It indicates the potential real-world benefits that patients might experience from the drug.