Aug. 18, 2010

A Self-Assessed Lupus Organ Damage Instrument

Development and initial validation of a self-assessed lupus organ damage instrument
Authors: Costenbader KH, Khamashta M, Ruiz-Garcia S, Perez-Rodriguez MT, Petri M, Elliott J, Manzi S, Karlson EW, Turner-Stokes T, Bermas B, Coblyn J, Massarotti E, Schur P, Fraser P, Navarro I, Hanly JG, Shaver TS, Katz RS, Chakravarty E, Fortin PR, Sanchez ML, Liu J, Michaud K, Alarcón GS, and Wolfe, F. (2010). 
Arthritis Care & Research 62: 559 - 568.

What is the topic?
When a person has a flare of lupus disease activity, the main goal of most treatments is to bring the inflammation under control. However, after the flare dies down, there may be some damage left, which is important to know about. By predicting the kind of damage that some people are more prone to, steps might be taken to prevent this damage. Also, some chronic symptoms, which patients have been told they need to “live with” because they are caused by damage, might be treatable if more attention is paid to them. The SLICC Damage Index (SDI), a 42-item questionnaire that physicians use to assess damage, was developed for this purpose and has been found to be useful in many studies about lupus.  

Use of the SDI, however, may not always be practical or possible. Therefore, researchers developed the Lupus Damage Index Questionnaire (LDIQ) for patients to fill out so that wider studies can be done where SDI evaluation from a physician is not available.  

What did the researchers hope to learn?
The researchers hoped to learn whether a lupus damage questionnaire, filled out by lupus patients instead of their doctors, would be accurate and/or useful.  

Who was studied?
1211 people with lupus, at least 19 years of age, participated in the study. 21 rheumatologists from 13 academic lupus medical centers also participated so that the answers could be compared.  

How was the study conducted?
The study was conducted in three parts by researchers at Brigham and Women’s Hospital and University of Alabama at Birmingham. First, an initial version of the patient questionnaire was developed. This was called the LDIQ and had 55 questions similar to the SDI, but written in understandable language, avoiding medical terms. This form was filled out by 37 people with lupus and their rheumatologists completed the SDI separately without knowing their patients’ LDIQ responses. Second, after comparing the patients’ and doctors’ responses, a revised version of the LDIQ was sent to 569 patients at lupus clinics in the U.S., Canada, and U.K.; in most of these cases, rheumatologists completed the SDI separately during an office visit without knowing their patients’ LDIQ responses. Third, the LDIQ was sent to 605 community-based lupus patients located through the National Data Bank for Rheumatic Diseases (NDB). These patient responses were compared to their responses to two other questionnaires that have already been tested and widely used (SF-36 and Systemic Lupus Erythematosus Activity Questionnaire).   

The patients were not identified during the analysis of the results to protect their privacy. For each question on the LDIQ, patient responses were recorded as one of the following based on comparison with physician responses to the SDI: true-positive, true-negative, false-positive, or false-negative. In other words, if the answer was positive and it matched the physician’s answer, it was called “true-positive.” If the answer was negative and it did not match the physician’s answer, it was considered “false-negative.” Although it cannot be assumed that the physician was always correct, when an answer did not match that of a patient, most of the items being looked at were specific, objective medical diagnoses. This increases the odds that the physician would be correct. Here, the goal was to develop a questionnaire without unnecessary medical terminology that would optimize the chances that a patient could accurately report these medical diagnoses, and respond as closely as possible to the answers their doctors would give. These results were then analyzed to determine how close the patients’ responses were to those of the physicians, and what factors might be associated with specific kinds of LDIQ responses.      

What did the researchers find?
The lupus patients who participated in the study were mostly women who had lupus for 10-16 years.

For the initial LDIQ, there was about 94% agreement among responses from patients and doctors. After those results were looked at, several items on the initial LDIQ were revised in the hopes of improving the similarity of responses.  

The revised LDIQ took patients less than 10 minutes to complete. This was a much larger study, involving a large group of doctors and their patients. There was at least 86% agreement among patients’ responses on this revised version of the LDIQ and physicians’ responses to the SDI, which was a very good result for this broader population. The main areas where the agreement was less close included: nerve damage (neuropathy), decreased kidney function, damage to the joints, and hair loss. Agreement was low for items about heart attacks, loss of body tissue, digestive problems, and surgery.  

In the community-based part of the study, there was only a little less agreement in responses, with an average agreement of 81%. 

The most common kinds of damage reported by patients using the LDIQ were in the nerves and muscles. The most commonly reported items were nerve damage (neuropathy), followed by damage from arthritis in the hands, and cataracts in the eyes. 

What were the limitations of the study?
The LDIQ was assessed using responses from physicians as the Gold Standard. However, the physicians may not have always had access to complete medical records and can also make mistakes since they are human.

What do the results mean for you?
The results demonstrate that the LDIQ may be reliably used to get a fairly accurate idea of organ damage across a broad range of people with lupus. Since some community-based physicians may not be familiar with the SDI, and might not have interest in participating in a given study, a patient-based initiative could add valuable information about lupus in larger groups of people and the LDIQ may be appropriate to use in such studies. It should be assumed that the data obtained in this way is unlikely to be perfect, but it has been shown that the data are pretty close to what you would get by polling doctors.

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