Seizure: July 2012
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Readers' choice
Each month our Seizure Reviewers read the summaries of the articles in the latest issue of Seizure. They then decide which one should be readers' choice.
Using Rasch measurement theory to assess three depression scales among adults with epilepsy
- Elizabeth Reisinger Walker - Rollins School of Public Health, Emory University, 1518 Clifton Rd., Atlanta, GA 30322, United States
- George Engelhard Jr. - Division of Educational Studies, Emory University, 1784 North Decatur Road, Suite 240, Atlanta, GA 30322, United States
- Nancy J. Thompson - Rollins School of Public Health, Emory University, 1518 Clifton Rd., Atlanta, GA 30322, United States
Abstract
People with chronic conditions, such as epilepsy, are at a high risk for depression; however depression is often under-recognized and undertreated. Depression scales, including one specific to people with epilepsy, have been used for screening in this population, although none have been assessed with Rasch measurement theory. This study used Rasch analyses in order to evaluate and compare the psychometric properties of the modified Beck Depression Inventory, the Patient Health Questionnaire, and the Neurological Disorders Depression Inventory for Epilepsy in a sample of people with epilepsy and depression who participated in an intervention designed to reduce depressive symptoms. A secondary purpose was to assess item functioning across time. The sample includes 44 participants in the Project UPLIFT program who completed the assessments before and after taking part in the intervention. Results of the Rasch analysis indicate that the three depression scales functioned as intended. There was good overall targeting between the items and the sample, acceptable model-data fit, and good reliability of separation for persons, items, and time. The participants experienced a significant decrease in depressive symptoms from pre-test to post-test. This study illustrates the value of using model-based measurement with the Rasch model to combine items across the three depression scales. It also demonstrates an approach for analyzing and evaluating the results of small-scale intervention programs, such as the UPLIFT program.
Why we chose this article
By – Helen Lowe – Seizure reviewer
Helen is a PhD student who has a background in both psychological and health sciences research. She has both a research interest in, and personal experience of epilepsy.
Aim of the study?
The aim of the study was to use an analysis technique (Rasch measurement theory) to compare the contents of three depression measures (scales) in a sample of people diagnosed with epilepsy, in order to see whether they match their purpose.
How was the research carried out?
The assessment of the scales took place as part of a larger study, which was trying to see if symptoms of depression could be reduced. The contents of three different scales aimed at measuring symptoms of depression were assessed. Two were depression scales are ones which can be used with individuals with or without epilepsy, and one is a scale designed specifically for use with people with epilepsy (PWE).
What did the researchers find out?
The PWE’s depression scores reduced after they took part in the study aimed at reducing the symptoms. The scales were found to be appropriate measures of depression in the group of PWE diagnosed with depression. It was suggested that if one scale missed out a key symptom of depression, than another picked it up. Therefore using a combination of the different scales for detecting symptoms of depression in PWE is important.
Why is this research important to people with epilepsy?
This research highlights the possibility of having depression alongside epilepsy. Being aware of the possibility of having depression may help PWE come to terms with depression being a possible cause of some of their symptoms. This may help PWE consider speaking to a healthcare professional such as a neurologist, an epilepsy nurse or their GP in order to discuss these symptoms and gain help.
Why I like this study
The research is of relevance to a wide variety of PWE. As the authors highlight, depression is the most common psychiatric disorders associated with epilepsy. This research makes PWE and healthcare professionals more aware of this. It reassures PWE that if they are experiencing depressive symptoms than that it is not uncommon, they are not alone. It also reassures PWE that there are tests available and possible ways of helping them to reduce their symptoms.
Interview with the author
Name: Elizabeth Reisinger Walker, MPH, MAT, George Engelhard, Jr., PhD, Nancy Thompson, PhD, MPH
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| Elizabeth Reisinger Walker | George Engelhard, Jr | Nancy Thompson |
How did you become interested in epilepsy?
Elizabeth: I became interested in epilepsy as a Master’s student. I initially worked on the WebEASE project, which is an online epilepsy self-management program. I then also became involved with the Project UPLIFT program described in the paper. I am drawn to the stories of people with epilepsy, and the power of sharing those stories. My dissertation research on epilepsy and support has developed out of this interest.
George: I typically work on measurement issues related to educational achievement testing. Liz enrolled in an advanced research seminar with me at Emory University, and we found that many of the current advances in psychometrics offered opportunities to improve assessment practices related to the measurement of depression among people with epilepsy.
Nancy: Right before I started my doctorate in psychology, my mother had a stroke and developed epilepsy. During the second year of my doctoral program, a close friend got a traumatic brain injury and also developed epilepsy. As a result, I minored in neuropsychology and have worked extensively with brain injury.
What issues inspired you to carry out this research?
People with epilepsy have very high rates of depression, which is a significant health burden that affects quality of life and individuals’ ability to manage their condition. However, depression in people with epilepsy often goes undiagnosed and untreated. Nancy became interested in finding a way to reach people with epilepsy, and developed the UPLIFT program. During its development, different epilepsy colleagues kept suggesting different depression measures, with little agreement. Therefore, we used three different measures, to be certain we would be able to accurately identify and measure symptoms of depression. Elizabeth and George decided it would be valuable to examine these common measures of depressive symptoms using an analytic technique that, to our knowledge, had not yet been used for people with epilepsy.
Did you involve people with epilepsy when you were designing the study?
Although people with epilepsy were not involved in the design of this current analysis, they were integral in the development of Project UPLIFT, which is the program from which the data in this study were collected. People with epilepsy provided valuable information that shaped the program before its pilot testing and evaluated the measures used in the study.
What methods did you use and why?
We used a technique, called Rasch measurement models, to examine three commonly used scales that measure depressive symptoms. This technique allowed us to place both the people with epilepsy who participated in the study and the questions from the scales along a common ruler, to see where people and questions fell on a continuum from low to high depression. For example, a question about feelings of frustration would be low on the continuum and a question about hurting one’s self would be high on the continuum.
There have been many recent advances in measurement, and Rasch measurement models are emerging as one of the key methodological tools for understanding quality of life in many areas. We are very excited about the transition of these new methods from theory into practice.
What did you find out?
Overall, the questions from the depression scales were spread across the continuum, indicating that they measured symptoms from low to high depression. The questions also matched up well to the spread of people with epilepsy across the continuum. None of the scales covered the full range of depression on their own, however. This means that each scale had gaps in measuring depression.
What impact do you think your findings will have on the diagnosis/treatment/care?
The results from this study indicate that more than one depression scale may be needed to fully gauge the scope of depressive symptoms in people with epilepsy. For example, a short depression screening measure could be followed up by a longer scale.
What further research is needed in this area?
Additional use of Rasch analyses could provide information about: 1) how and why individuals respond in certain ways to the different questions about depressive symptoms; 2) how scales could be revised to better assess depression in people with epilepsy; 3) how well these scales measure depression compared to a structured psychological interview, which is the gold-standard for diagnosing depression; and 4) ways in which symptoms overlap between depression and epilepsy. Future research on additional indices of quality of life among people with epilepsy using Rasch measurement can provide evidence-based information for understanding the well-being of people with epilepsy, and the efficacy of various support services.
What other research are you involved with at the moment?
Elizabeth: For my dissertation, I interviewed and surveyed people with epilepsy and their primary support providers to see what support is provided and how that support influences depression and self-management.
Nancy: I am continuing to conduct research on Project UPLIFT. I have just completed one study showing that it can be used to prevent, as well as to treat, depression. I am just beginning a study of Project UPLIFT for people with Cystic Fibrosis. I am also evaluating the reduction in fatal crashes as a result of Georgia’s graduated licensing law over the 10 years since its implementation.
George: I plan to continue working on the translation of theoretical advances in measurement in the human sciences into practical and useful measures for understanding and improving quality of life.
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