Purpose: You will be able to demonstrate a general understanding of interpreting statistical output to evaluate sensitivity and specificity, odds ratios, relative risks, and survival analysis.
Instructions: Answer each item on this worksheet below and then upload this worksheet under the ASSIGNMENTS section in blackboard.
For Questions 1-6: An emergency department received a grant from the local public health department to offer rapid HIV testing for all patients 14-28 years old regardless the patients’ chief complaints. A pilot study was conducted using two different rapid HIV tests. The following charts detail the findings for each test.
| TEST “A” RESULTS | TEST “B” RESULTS | |||||
| Confirmed HIV positive | Confirmed HIV negative | Confirmed HIV positive | Confirmed HIV negative | |||
| Test A: positive | 12 | 10 | Test B: positive | 17 | 3 | |
| Test A: negative | 2 | 20 | Test B: negative | 2 | 20 | |
- What was the sensitivity for Test “A”? (5 points)
- What was the specificity for Test “A”? (5 points)
- What was the sensitivity for Test “B”? (5 points)
- What was the specificity for Test “B”? (5 points)
- Should Test “A” or Test “B” be recommended for screening emergency department patients for HIV? (5 points)
- Provide a rationale for your decision. (10 points)
For Questions 7-8: A team of emergency nurse practitioners conducted an epidemiological cohort study to examine patients who returned to the emergency department within one week compared to patients who did not return to the emergency department within one week based on the patients’ clinical providers (physician versus nurse practitioner). They enrolled subjects in the study prospectively and documented whether their care was provided by a physician or a nurse practitioner and then they monitored the ED’s patient census for the following week and documented if the patients returned for care or not.
- Based on the study design, would an odds ratio or relative risk be the appropriate test statistic to use when analyzing their data? (5 points)
- Why was this test statistic appropriate? (5 points)
For Questions 9-14: A team of researchers conducted a randomized trial enrolling patients with locoregionally advanced head and neck cancer. Participants were randomized to one of two groups: one group received treatment with radiotherapy only and the other group received treatment with both radiotherapy and weekly cetuximab. Duration of time until progression of the cancer is depicted below:
- What type of graph is displayed in the figure above? (5 points)
- What increment of time was displayed in the figure above? (5 points)
- What is displayed on the Y axis (vertical axis) of this figure? (5 points)
- At the beginning of the study (Month 0), how many patients had not experienced progression? (5 points)
- At what approximate month had 60% of patients in the radiotherapy only group HAD experienced progression? (5 points)
- At what approximate month had 60% of patients in the radiotherapy and cetuximab group HAD experienced progression? (5 points)