91Ó°ÊÓ

The following portion of an abstract gives information on the comparison of treatments of men with prostate cancer. Read it and answer the questions about it below. The prostate gland surrounds the neck of the bladder in men. "Methods: Between 1989 and 1999 , we randomly assigned 695 men with early prostate cancer to watchful waiting or radical prostatectomy and followed them through the end of 2012\. The primary end points in the Scandinavian Prostate Cancer Group Study Number 4 (SPCG-4) were death from any cause, death from prostate cancer, and the risk of metastases. Results: During \(23.2\) years of follow-up, 200 of 347 men in the surgery group and 247 of the 348 men in the watchfulwaiting group died. Of the deaths, 63 in the surgery group and 99 in the watchful-waiting group were due to prostate cancer; the relative risk was \(0.56(95 \%\) confidence interval, \(0.41\) to \(0.77 ; \mathrm{P}=0.001\) ), and the absolute difference was \(11.0\) percentage points (95\% CI, \(4.5\) to \(17.5\) ). The number needed to treat to prevent one death was \(8 .\) One man died after surgery in the radical-prostatectomy group.... The benefit of surgery with respect to death from prostate cancer was largest in men younger than 65 years of age (relative risk, \(0.45\) ) and in those with intermediate-risk prostate cancer (relative risk, \(0.38\) ). However, radical prostatectomy was associated with a reduced risk of metastases among older men (relative risk, \(0.68\); \(\mathrm{P}=0.04) . "\) (Source: Anna Bill-Axelson et al. 2014. Radical prostatectomy or watchful waiting in early prostate cancer. New England Journal of Medicine \(370,932-942 .\) ) a. Compare the percentages of death for the two groups descriptively. Which group had patients who were more likely to live? b. Find and compare the percentage who died from prostate cancer for each group. c. Was this an observational study or a controlled experiment?

Step by step solution

01

Identify and compare percentages of overall deaths

From the information given in the abstract, the percentage of deaths in the surgery group is \(200/347 \times 100 = 57.6\% \), the percentage of deaths in the watchful-waiting group is \(247/348 \times 100 = 71.0\%\). Therefore the group that underwent surgery is more likely to live.

02

Identify and compare percentages of prostate cancer deaths

From the given abstract, the percentage of deaths due to prostate cancer in the surgery group is \(63/347 \times 100 = 18.2\%\). The percentage of deaths due to prostate cancer in the watchful-waiting group is \(99/348 \times 100 = 28.45\%\). Thus, the percentage of people who died from prostate cancer was lower in the surgery group.

03

Identify the type of study

This study is a controlled experiment. The main indicator of this is the use of random assignment of the treatment (surgery or watchful waiting) to the men with early prostate cancer.

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Key Concepts

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

Controlled Experiment

A controlled experiment is a powerful method in the scientific field used to test the effectiveness or impact of a treatment or intervention. In the case of the prostate cancer study, it means that researchers set up an experiment with specific conditions and controls. They could oversee all variables and make fair comparisons between the groups.

• In a controlled experiment, researchers divide participants into groups, like the surgery and watchful waiting groups in this study.
• One group receives the treatment being tested (surgery in this example), while the other group might receive an alternative treatment or nothing at all (watchful waiting).

This approach allows researchers to isolate the effects of the treatment on outcomes, such as death from prostate cancer. Importantly, because it is controlled, researchers can draw strong conclusions about whether differences in outcomes are due to the treatment itself or other factors.

Statistical Analysis

Statistical analysis plays a key role in controlled experiments by helping researchers interpret the data they collect. In our prostate cancer study, statistical methods were used to analyze survival rates and cancer-specific outcomes.

• Statistics help convert complex results into understandable numbers, such as percentages or risk ratios.
• These numbers allow researchers to compare different outcomes across groups.

For example, researchers found that the relative risk of dying from prostate cancer was significantly lower in the surgery group compared to the watchful waiting group.
By using confidence intervals (like 95% confidence intervals) and p-values, statistical analysis helps determine the reliability and significance of the results, supporting conclusions about treatment effectiveness.

Comparative Study

A comparative study involves directly comparing different treatments or interventions to find out which is more effective. In our case, the prostate cancer study compared the outcomes of men who underwent surgery with those who had watchful waiting.

• Through a comparative study, researchers were able to determine which approach—surgery or watchful waiting—helped men live longer or reduced their chances of dying from prostate cancer.
• This comparison is based on endpoints such as the number of deaths or progress of the disease among participants.

The study's findings that surgery reduced death rates provide valuable information to help doctors and patients make informed decisions about treatment options.
This way, comparative studies play a crucial role in advancing medical knowledge and practice.

Random Assignment

Random assignment is a cornerstone of fair testing in a controlled experiment. It involves randomly distributing participants into different groups, ensuring each participant has an equal chance of being in any group.

• This method minimizes biases that could skew the study’s findings.
• Random assignment helps ensure that observed differences between groups are likely due to the treatment, rather than pre-existing differences among participants.

In the prostate cancer study, random assignment was used to allocate men to either the surgery group or the watchful waiting group, ensuring the study's credibility.
Using random assignment enhances the reliability of the experiment's conclusions and ensures the study can be trusted when guiding medical treatments and patient choices.