Dec. 02, 2011

Interview-Driven, Patient-Reported Lupus Damage

Brief index of lupus damage: a patient-reported measure of damage in systemic lupus erythematosus
Yazdany J, Trupin L, Gansky SA, Dall’era M, Yelin EH, Criswell LA, and Katz PP. (2011).  Arthritis Care & Research (Hoboken) 63: 1170-1177.

What is the topic?

It is important for both doctors and patients to understand lupus-mediated damage, which can affect a number of parameters including physical functioning, health care utilization, and disability. Such damage has traditionally been determined by a physician with the use of the Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology Damage Index (SDI). Use of the SDI, however, is most often limited to research settings and requires administration by a physician trained to complete this extensive questionnaire. 

As people with lupus have become increasingly educated about their disease and involved in their medical care, input from patients about their condition has become increasingly important and useful. Recently, the Lupus Damage Index Questionnaire (LDIQ) was developed for this purpose and captures the spectrum of knowledge acquired from the SDI in a patient-reported questionnaire. 

This study describes the development of the Brief Index of Lupus Damage (BILD), which parallels the spirit of the LDIQ, but differs in that it is administered by an interviewer as opposed to being a written questionnaire like the LDIQ. The BILD was developed as a telephone interview to capture the essential information gleaned from the SDI, but was modified to include only non-technical language. 

What did the researchers hope to learn?

The researchers hoped to learn about the validity of the BILD by comparison to the LDIQ and SDI. 

Who was studied?

798 people with lupus were recruited to participate in the study from a variety of sources.

How was the study conducted?

Patients obtained from two primary sources participated in the study to evaluate the validity of the BILD, a new patient-reported measure that estimates organ damage in people with lupus. 

One population of 81 patients included those who visited the University of California at San Francisco Lupus Center or the San Francisco General Hospital Lupus Clinic between February and September 2009 or between December 2010 and February 2011. These patients, called the “clinical sample,” were given the BILD questionnaire via telephone about four months prior to their next clinic visit, at which time they completed the LDIQ while in the waiting room. During the clinic visit itself, a rheumatologist filled out the SDI. In this way, results from the BILD, LDIQ, and SDI could all be compared against each other.

A second population of 717 patients included those recruited to the study via university-based and community-based rheumatology clinics, as well as non-clinical sources such as support groups, conferences, and other forms of media. These patients, called the “LOS sample,” are part of an ongoing effort known as the Lupus Outcomes Study (LOS). During their annual LOS telephone interview, these patients were given the BILD, and also answered questions about demographic information, quality of life, health status, health care utilization, disease activity, and employment status. 

For this study, the SDI was considered the “gold standard,” meaning that the validity of new outcome measures like the BILD can be determined by statistical comparison with the results of the SDI. In order to help determine the validity of the BILD, its results were compared statistically to those of the LDIQ and the SDI. 

What did the researchers find?

The observed agreement between the BILD and the SDI ranged from 75%-100%, while that between the LDIQ and the SDI (for those items retained in the BILD) ranged from 77%-100%. The entire set of responses from the BILD was statistically similar to those of the SDI. The same was true for the LDIQ and SDI.

Both samples included participants that were mostly women. Compared to the LOS sample, patients in the clinical sample were younger, had been diagnosed with lupus more recently, and included a larger proportion of patients that were ethnic minorities. The LOS sample participants had moderate disease activity over the past four years and scored typically on a questionnaire about physical functioning (that is, typical for a patient with a chronic condition and worse than scores from people in the general population). Fewer than half of the LOS patients were employed and about a third reported experiencing work disability. 

Among the LOS sample, the acceptability of the BILD was very high, with only four items that more than 1% of people did not respond to. Higher BILD scores (indicating greater damage) were associated with the following: a) increased age; b) greater proportion of sample respondents with incomes below poverty; c) greater proportion of respondents indicating poor health status and work disability; d) greater proportion of sample respondents unemployed; e) longer disease duration; f) more hospitalizations; g) a greater number of physician visits for lupus over the past five years; and h) lower scores on a quality of life questionnaire. Advanced statistics indicated that the strongest indicators of disease damage included disease duration and poverty. There was no clear relationship between disease-related damage and ethnicity/race or sex. 

What were the limitations of the study?

This study did not evaluate the reliability of the BILD. For example, future studies should test the BILD for how similar consecutive scores on the same test (from the same individuals) are, especially when the BILD is administered by different interviewers. In addition, the BILD should be administered to a larger, more ethnically diverse group of lupus patients to help determine whether BILD scores may differ by ethnicity. 

What do the results means for you?

The BILD can be a useful tool in studying lupus disease-related damage, especially in community settings where there may be fewer physicians who are also researchers trained in using the SDI. Since the BILD does not duplicate every item on the SDI, it is not intended to replace it. However, the BILD can provide valuable information than can help differentiate between patients with low or high degrees of disease damage and may allow or facilitate earlier interventions.


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