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Rheumatoid arthritis (RA) is a chronic and progressive inflammatory musculoskeletal disease (1–3), affecting approximately 2.1 million Americans (4). The course of the illness can result in joint destruction, impaired psychological and social functioning, as well as increased mortality (2–5). Economically, the disease is responsible for $4.2 billion in medical costs annually (6). Annual indirect costs (primarily due to premature disability) are estimated to be between $13,180 and $65,880 per patient. Indirect costs are estimated to be higher than direct costs due to the disability experienced by the majority of RA patients within 10 years of disease onset (7). Significant resources have been devoted to developing new treatments in an effort to reduce the impact of RA at the individual and societal levels. Accompanying this effort is the need to accurately assess changes in different aspects of patients' health including physical function and health-related quality of life (HRQOL) due to disease activity and therapeutic efficacy.
Health-related quality of life refers to those aspects of human life and activities that are generally affected by health conditions or health services (8). Many instruments have been applied to measure the HRQOL of patients with RA. These instruments are categorized as generic (e.g., the Medical Outcomes Study Short-Form 36 [SF-36]) (9) or disease-specific (e.g., Arthritis Impact Measurement Scale [AIMS]) (10, 11).
Unlike disease-specific instruments, generic instruments contain general health questions that allow for comparisons across diseases (12). However, generic instruments often do not include items that are uniquely relevant to patients with different diseases. Consequently, they tend to be less responsive than those that are disease-specific (3, 13, 14). Yet, few RA disease-specific HRQOL instruments have been developed. Well-validated instruments, such as the Health Assessment Questionnaire (HAQ) Disability Index, which have been used extensively in clinical trials, (15) measure functional status, not the broader and more inclusive construct of HRQOL. Further, HRQOL instruments that are in use were initially developed over 20 years ago (e.g., the AIMS), limiting the extent to which they may completely address current vernacular and patterns of daily life for patients with RA. This is especially pertinent given the new realities of more aggressive and early management of RA in the 1990s with costly interventions that could potentially possess unique adverse effects. Further, such instruments may not be sufficiently sensitive or responsive to detect relatively small changes in HRQOL associated with newly developed clinical interventions (16). Thus valid, reliable, and sensitive RA-specific HRQOL instruments are needed as new therapeutic advances that could potentially reduce the impact of disease on patients' overall health are introduced.
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In order to allow for a comprehensive representation of HRQOL issues specific to rheumatoid arthritis, the items of the CSHQ-RA were derived from a rich item pool that incorporated past HRQOL instruments validated in RA samples; an analysis of transcripts from several patient focus groups that enabled the instrument to capture, in patients' current vernacular, their perceptions and concerns; and the input of expert clinicians to verify the clinical relevance of items. Psychometric properties were tested among patients diagnosed with RA.
The CSHQ-RA was developed to assess the broader impact of RA on patients' HRQOL. Recognition of the importance of assessing multidimensional aspects of HRQOL has been demonstrated in both the Arthritis Impact Measurement Scales 2 (AIMS2) (21) and the Multidimensional Health Assessment Questionnaire (46) Yet, unlike many of the RA instruments, the CSHQ-RA employs a consistent response format (i.e., a 5-point Likert scale) throughout all 33 items, along with a single, non-varying (e.g., “at this moment,” “in the past week,” “in the future”) timeframe of reference in an effort to increase reliability and validity. Further, to reduce the chances of attribution error, respondents are instructed to answer each question by considering only how RA has impacted various aspects of their HRQOL. However, it is recognized that such a statement does not rule out the possibility of patients including secondary or unrelated influences that impact HRQOL, such as pain or fatigue.
In the development process, an effort was made to reflect current issues, such as the use of a computer keyboard (versus a typewriter), worry associated with being able to afford RA medications, and concern over the side effects of treatments. Creating an instrument based on input from RA patients at the present time was also intended to address specific attributes of newer RA therapies and their effects, with questions exploring the frequency of fatigue and worry over the long-term consequences of RA, such as disability and joint destruction. Although further testing is necessary, it is hoped that the CSHQ-RA will offer both researchers and clinicians a more comprehensive view of patients' health than traditional clinical outcomes. This is especially important given that physiologic measures, while providing valuable information, often correlate poorly with areas that are of greatest interest to patients such as functional capacity and well-being (47).
There are several limitations to the present study. First, it should be noted that generalizability is limited to patients who are white, college educated, and physically able to complete the questionnaire. Yet, the preponderance of females in the sample is consistent with the typical demographics of this disease (4). Furthermore, in an effort to stay within a short test-retest period, only the first 350 patients who responded to the invitation were included in the study, introducing the possibility of selection bias. Due to the cross-sectional nature of the study sensitivity and responsiveness to changes in patients' perceived health status of the CSHQ-RA were not determined in this study.
Another potential limitation of the CSHQ-RA, in its current form, is that not all domains believed to be potentially relevant to health-related quality of life were included in the final instrument. For example, items intended to assess social well-being were either eliminated or not separated from other subscales as a result of factor analysis. Yet, this domain has been identified as an important area in HRQOL assessment (48–50). Reasons for this occurrence could include a poor choice of initial items representing social well-being, or the incorporation of this construct within items included in other domains. Further development of the instrument focusing on the social domain is currently being undertaken.
Six supplemental questions were designed to assess the frequency of side effects caused by RA treatment. Currently, there is considerable debate concerning the appropriateness of including side-effects as a part of HRQOL assessment. For example, 3 of the 5 responders from the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Quality of Life Guidance Committee (51) agreed that side effects may impact HRQOL but should be considered as separate. However, different drugs have very different toxicity profiles (52), requiring an exhaustive list in order to cover all possible side effects. Therefore, the side effect questions are offered in the present study as supplements that could potentially provide important clinical information.
The CSHQ-RA is a disease-specific health-related quality of life instrument for rheumatoid arthritis that with high internal consistency and reproducibility. The instrument is intended to reflect modern options available to RA patients, including aggressive and costly treatment choices with potent (even unknown or newly emerging) toxicities. Further justification for the development of a new instrument is that the CSHQ-RA is intended to be both multidimensional and disease-specific. These factors allow the CSHQ-RA to assess elements of patients' HRQOL that are not captured by commonly used disease-specific instruments, such as the HAQ, which measures only functional status. The CSHQ-RA may similarly offer advantages over generic HRQOL measures such as the MOS SF-36 that can be relatively insensitive to changes in health states of patients with specific clinical conditions. Additional aspects of reliability (i.e., test-retest) and validity (e.g., convergent and divergent validity) of the CSHQ-RA have been reported elsewhere (53) and are being submitted for full publication.