Study Design — MCQs

A study is funded by the tobacco industry to examine the association between smoking and lung cancer. They design a study with a prospective cohort of 1,000 smokers between the ages of 20-30. The length of the study is five years. After the study period ends, they conclude that there is no relationship between smoking and lung cancer. Which of the following study features is the most likely reason for the failure of the study to note an association between tobacco use and cancer?

A researcher is conducting a study to compare fracture risk in male patients above the age of 65 who received annual DEXA screening to peers who did not receive screening. He conducts a randomized controlled trial in 900 patients, with half of participants assigned to each experimental group. The researcher ultimately finds similar rates of fractures in the two groups. He then notices that he had forgotten to include 400 patients in his analysis. Including the additional participants in his analysis would most likely affect the study's results in which of the following ways?

A recent study attempted to analyze whether increased "patient satisfaction" driven healthcare resulted in increased hospitalization. Using this patient population, the sociodemographics, health status, and hospital use were assessed. Next year, patient satisfaction with health care providers was assessed using 5 items from the Consumer Assessment of Health Plans Survey. Which of the following best describes this study design?

Researchers are studying the relationship between heart disease and alcohol consumption. They review the electronic medical records of 500 patients at a local hospital during the study period and identify the presence or absence of acute coronary syndrome (ACS) and the number of alcoholic drinks consumed on the day of presentation. They find that there is a lower prevalence of acute coronary syndrome in patients who reported no alcohol consumption or 1 drink daily compared with those who reported 2 or more drinks. Which of the following is the most accurate description of this study type?

A study is conducted to find an association between serum cholesterol and ischemic heart disease. Data is collected, and patients are classified into either the "high cholesterol" or "normal cholesterol" group and also into groups whether or not the patient experiences stable angina. Which type of data analysis is most appropriate for this study?

The objective of one case-control study was to assess whether a history of past trauma represents a risk factor for the development of spondyloarthritis. Cases of spondyloarthritis were compared with a random sample taken from the general population in regards to a history of prior trauma. This kind of history, which in turn increased the likelihood of being subjected to X-ray imaging investigations, led to a higher likelihood of diagnosing spondyloarthritis in these individuals compared with the general population. This resulted in a significantly higher proportion of spondyloarthritis in study participants with prior trauma, with the resulting overestimation of related odds ratio. In which case is the bias in this example more likely to occur?

A physician attempts to study cirrhosis in his state. Using a registry of admitted patients over the last 10 years at the local hospital, he isolates all patients who have been diagnosed with cirrhosis. Subsequently, he contacts this group of patients, asking them to complete a survey assessing their prior exposure to alcohol use, intravenous drug abuse, blood transfusions, personal history of cancer, and other medical comorbidities. An identical survey is given to an equal number of patients in the registry who do not carry a prior diagnosis of cirrhosis. Which of the following is the study design utilized by this physician?

Your colleague has been reading the literature on beta-carotene supplementation and the risk of heart disease. She thinks they may share a clinically relevant association and would like to submit an editorial to a top journal. Upon final literature review, she discovers a newly published study that refutes any association between beta-carotene and heart disease. Your colleague is upset; you suggest that she, instead, mathematically pool the results from all of the studies on this topic and publish the findings. What type of study design are you recommending to your colleague?

A researcher is examining the relationship between socioeconomic status and IQ scores. The IQ scores of young American adults have historically been reported to be distributed normally with a mean of 100 and a standard deviation of 15. Initially, the researcher obtains a random sampling of 300 high school students from public schools nationwide and conducts IQ tests on all participants. Recently, the researcher received additional funding to enable an increase in sample size to 2,000 participants. Assuming that all other study conditions are held constant, which of the following is most likely to occur as a result of this additional funding?

A case-control study looking to study the relationship between infection with the bacterium Chlamydia trachomatis and having multiple sexual partners was conducted in the United States. A total of 100 women with newly diagnosed chlamydial infection visiting an outpatient clinic for sexually transmitted diseases (STDs) were compared with 100 women from the same clinic who were found to be free of chlamydia and other STDs. The women diagnosed with this infection were informed that the potential serious consequences of the disease could be prevented only by locating and treating their sexual partners. Both groups of women were queried about the number of sexual partners they had had during the preceding 3 months. The group of women with chlamydia reported an average of 4 times as many sexual partners compared with the group of women without chlamydia; the researchers, therefore, concluded that women with chlamydia visiting the clinic had significantly more sexual partners compared with women who visited the same clinic but were not diagnosed with chlamydia. What type of systematic error could have influenced the results of this study?