Treating Depression: A Randomized Clinical Trial

Background

Clinical depression is a recurrent illness requiring treatment and often hospitalization. Nearly 50% of people who have an episode of major depression will have a recurrence within 2-3 years. Being able to prevent the recurrence of depression in people who are at risk for the disease would go a long way to alleviate the pain and suffering of patients and would also save society many thousands of dollars in medical expenses and lost wages due to an inability to work.

The Study

During the 1980's the federal government, through the National Institutes of Health (NIH), sponsored a multi-centered, randomized, controlled, clinical trial to evaluate two drugs to prevent the recurrence of depression in patients who have had at least one previous episode of the illness (Prien et al., Archives of General Psychiatry, 1984).

The Study Design

The study was multi-centered. There were 5 medical clinics in major metropolitan areas across the United States that participated in this trial. Using many clinics enabled the investigators to enroll many more patients into the study and allowed for more diversity in the patients who participated. There were 3 treatment groups. Patients received either Imipramine (Imip), Lithium (Li), or a Placebo (Pl) where Imip and Li are active drugs. Patients were randomly assigned to one of the 3 treatment groups. Like most other medical studies where new, unexplored treatments are evaluated, patients chose themselves to participate in the study by signing a consent form. Patients were followed for 2-4 years to see whether or not they had a recurrence of depression. If they did not have a recurrence within this time frame, then their treatment was considered a "success". If they did have a recurrence, it was considered a "Failure." The study was double-blinded. A number of additional background variables were measured for each patient.

Variables

AcuteT The number of days the patient had been depressed before the current study started

Treat L=Lithium; I=Imipramine; P=Placebo

Outcome S=Success F=Failure (depression returns)

The Data

Here is the data collected from the study:Drug Depression AcuteT Dataset

(Links to an external site.)

Part 2:

1. Before administering the treatments (the drugs) the researchers wanted to compare the distribution of AcuteT for each treatment group. Why do you think this is important?
2. UseArt of Stat(Links to an external site.)or other statistical tool calculate and report the following statistics for the AcuteT variable for each of the three treatment groups.
   • Mean
   • Standard Deviation
   • Median
   • IQR
3. Below is a graphical summary of theAcuteTvariable for the three treatment groups.What is the name of the type of graph is shown in the graphical summary. Image Description of the Graphical Display:
   • For the Imipramine treatment group, we see the lines at 47, 131, 166, 212, and 322, then three circles with the highest at 428.
   • For the Lithium treatment group, we see the boxplot lines at 48, 113, 173, 211.75, and 294, and a circle at 441.
   • For the Placebo group, we see lines at 70, 140, 163.5, 246, and 339, with two circles, the highest being at 512.
4. Describe and compare the shapes of each distribution in the graph.
5. Describe and compare the centers of each distribution in the graph.
6. Describe and compare the variability (spread) of each distribution in the graph.
7. Are there any outliers in any of the treatment groups? If so are they individuals who have been depressed for a short amount of time or a long amount of time? How long or short?
8. Use your answers from part 2 to write one or two sentences that describes if you believe the three treatment groups are mostly similar and comparable or very different from one another, when it comes to AcuteT.