During initial clinical trials of the novel medication Xylofen, every participant possessi… — LSAT

During initial clinical trials of the novel medication Xylofen, every participant possessing the genetic mutation K-22 experienced a complete cessation of migraine symptoms within $24$ hours of administration. Participants lacking the K-22 mutation exhibited highly variable responses in the clinical trials, with some experiencing complete cessation and others reporting no effect. The K-22 mutation is present in precisely $30\%$ of the general population who suffer from migraines. When Xylofen was approved and introduced into general medical practice, physicians prescribed it to migraine sufferers without testing for the K-22 mutation, resulting in the drug being distributed to patients with and without the mutation in exact proportion to their representation in the migraine-suffering population. Nevertheless, data from the first year of general practice showed that only $10\%$ of all patients prescribed Xylofen experienced a complete cessation of symptoms within $24$ hours.

Which of the following is most strongly supported by the information above?

A
The failure of Xylofen to produce complete symptom cessation in the vast majority of general practice patients was due to differences in the demographic composition between the trial participants and the general population.
B
The absolute number of patients without the K-22 mutation who experienced a complete cessation of symptoms in general medical practice was greater than the number of patients with the K-22 mutation who experienced such a cessation.
C
In general medical practice, a majority of the patients who experienced a complete cessation of symptoms within $24$ hours were individuals who possessed the K-22 mutation.
Among patients who possess the K-22 mutation and were prescribed Xylofen, the proportion who experienced a complete cessation of symptoms within $24$ hours was lower in general medical practice than it was during the initial clinical trials.Answer
E
In the initial clinical trials, any participant who experienced a complete cessation of migraine symptoms within $24$ hours was guaranteed to possess the K-22 mutation.

Answer

The proportion of patients with the K-22 mutation who achieved complete symptom cessation was lower in general practice than in the clinical trials.

The stimulus provides enough quantitative data to calculate a mathematical upper bound for the success rate of the drug among K-22 patients in general practice. In the clinical trials,

100\%

of K-22 patients experienced complete cessation. In general practice, the K-22 group comprised

30\%

of all prescribed patients, yet the total success rate for all patients combined was only

10\%

. Even in the absolute best-case statistical scenario for the K-22 group—assuming that every single patient who achieved cessation was a K-22 patient—their success rate would only be

10

out of

30

, or approximately

33.3\%

. Since

33.3\%

is strictly less than the

100\%

success rate observed in the trials, it is a certainty that the proportion of K-22 patients experiencing cessation was lower in general practice.

Step-by-Step Solution

Analyze the clinical trial data for patients with the K-22 mutation.

Exactly

100\%

of trial participants with the K-22 mutation experienced a complete cessation of symptoms.

The stimulus explicitly states 'every participant possessing the genetic mutation K-22 experienced a complete cessation'.

Determine the demographic distribution of patients prescribed the drug in general practice.

The K-22 mutation group constitutes exactly

30\%

of the patients who were prescribed the drug in general practice.

The mutation is present in

30\%

of the target population, and the drug was prescribed in exact proportion to this representation.

Calculate the mathematical maximum possible success rate for K-22 patients in general practice.

The total cessation rate is

10\%

. Even if all of these successful outcomes occurred exclusively in the K-22 group, their cessation rate would be at most

10\% / 30\%

, which is roughly

33.3\%

To find an upper bound for a subgroup's rate, we must attribute the maximum possible number of successes to that subgroup.

Compare the rates between the clinical trials and general practice.

The general practice rate for the K-22 group (maximum

33.3\%

) is definitively lower than their clinical trial rate (

100\%

This guarantees that the correct answer choice is a provably true logical inference, fulfilling the requirements for Most Strongly Supported.

Key Concept

Synthesizing percentage subsets to determine mathematical upper bounds in logical inferences.

Estimated Time:2m 30s

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