This article assesses the effect of systemic lupus erythematosus (SLE) on the shealth-related quality of life (HRQOL) and employment of persons with this condition. Far more than impaired health status can affect an individual’s quality of life. The term “health-related quality of life” is used to connote the decrement in an individual’s quality of life specifically attributable to a decrease in health status. The article presents evidence on employment because this plays a crucial role in determining the quality of life of most Americans of normal working age. However, evidence is also presented with respect to other domains of activity, because most people work to live but not many live to work.
This article assesses the effect of systemic lupus erythematosus (SLE) on the health-related quality of life (HRQOL) and employment of persons with this condition. Far more than impaired health status can affect an individual’s quality of life. The term “health-related quality of life” is used to connote the decrement in an individual’s quality of life specifically attributable to a decrease in health status. The article presents evidence on employment because this plays a crucial role in determining the quality of life of most Americans of normal working age. However, evidence is also presented with respect to other domains of activity, because most people work to live but not many live to work.
Conceptualizing the effect of SLE on HRQOL is far more difficult than for rheumatoid arthritis (RA), let alone osteoarthritis (OA) or other nonsystemic musculoskeletal conditions. In RA, as opposed to OA, one has to take into account the effect of profound fatigue beyond the obvious effect of symmetric joint involvement and joint destruction. Symptoms like fatigue that are invisible to the observer may lead others to discount the effects of the condition. The disconnect between what others perceive and what the person with RA perceives may be a source of psychological disturbance. Also, the uncertainty associated with an uneven course of illness can also take a toll on the individual, not least because it makes planning for the future difficult. In SLE, some of the same issues arise, but may be amplified because of the range of manifestations that may occur, adding complexity to invisibility of some symptoms and uncertainty of course.
Thus, measuring the effect of SLE on HRQOL may be a daunting challenge. It is nevertheless a propitious time to take stock. There is good evidence that improved treatment of SLE has resulted in decreased mortality associated with the condition, turning a frequently fatal condition into one in which concern about quantity of life has segued into a concern about its quality.
Reflecting decreased mortality, the literature on the effect of SLE on quality of life and employment has grown substantially in recent years. For example, a comprehensive literature review on employment and SLE searched for articles on this topic from 1950 onward, but the earliest found was from 1994 and only another 8 were published before the end of the 1990s. Since 2000, 18 more have appeared, with 11 of these published after 2005.
However, the most important reason to take stock of the effect of SLE on quality of life and employment is that, for the first time in memory, new treatments may be imminent, particularly as the biologic era in rheumatology expands to encompass SLE. By estimating the effect of SLE on quality on life now, it will be possible to evaluate the effect of these new treatments as they diffuse into practice in the years to come.
A framework for discussing HRQOL in general is provided so that, from a review of some of the literature on HRQOL on SLE, the reader can see how groups of studies address the different elements in the framework. Often, literature reviews encompass studies across the elements without clarifying how these studies relate to the elements. The framework outlined incorporates integrative activities such as employment as the end result of a process that begins with the onset of SLE (or at an even earlier stage, the risk factors for onset), placing the studies of employment in the same framework as the remainder of the HRQOL literature.
Special attention is paid to the effect of SLE on employment among all of the integrative activities because SLE is typically diagnosed early in the career of those with the condition, perhaps limiting their ability to establish careers and, even if this is not the case, preventing them from gaining the kind of traction in work that normally occurs in the absence of a severe chronic disease.
Health-related quality of life
Throughout the course of their disease, individuals with SLE face considerable physical, psychological, and social challenges. As long-term survival in SLE has become commonplace, measures that move beyond mortality or medical morbidity to capture the patient’s perspective have become a critical aspect of appraising outcomes. Instruments that measure HRQOL attempt to characterize this subjective experience of illness. Rheumatologists have pioneered the measurement of HRQOL, dispelling notions that HRQOL is somehow not as important or valid as other traditionally used clinical end points. In fact, a growing body of literature demonstrates that HRQOL is a useful and valid end point for incorporation into clinical research and practice, and should be used alongside physician assessments and laboratory studies.
In SLE, considerable research has accumulated regarding HRQOL. This section defines the theoretical concepts underlying HRQOL and then, using a well-defined model, discusses what is known regarding HRQOL in SLE. The section ends with a brief discussion of the tools available to measure HRQOL in SLE, and recommends a general approach to selecting a measure for use in clinical practice or research studies.
Defining HRQOL
Although there is no universally accepted definition of HRQOL, the last several decades of scientific research suggest that it should be viewed as a multidimensional construct. This approach ensures that health status and quality of life are examined distinctly, with quality of life representing a more global view of the patients’ social and psychological environment that may influence the response to illness.
In 1995, Wilson and Cleary put forth what is now a classic model that emphasizes the multidimensional inputs to HRQOL ( Fig. 1 ). Although more than a decade old, the model is still useful in thinking about the relationships among the conceptual areas represented. The model begins with biologic and physiologic variables, which, in the case of SLE, might reflect factors such as an individual patient’s genetic predisposition to disease, autoantibody production, and organ manifestations. Second, the model contains symptom status, which relates the patient’s perception of his or her symptoms. In SLE, this would include the physical, cognitive, and emotional symptoms experienced by the patient. Third, functional status is assessed, which incorporates physical, psychological, and social functioning. These preceding domains are related to the fourth concept, general health perceptions, which entail a subjective synthesis of the preceding factors in the model. Finally, the last domain is overall quality of life, a global concept that may incorporate notions such as life satisfaction and overall ratings of quality of life. The model’s structure implies causal relationships between these content areas, with the dominant direction of causation proceeding from left to right. (The Wilson and Cleary model of HRQOL is remarkably similar to the Nagi model of work disability, more recently amended by Verbrugge and Jette, in which pathology, eg, SLE, begets impairment, eg, neuropsychiatric symptoms, which in turn beget functional limitations, eg, executive function, before affecting employment. The Nagi model is used in employment or work disability research. For space reasons, and because HRQOL would certainly include employment, this article focuses on the Wilson and Cleary HRQOL model.)
The next section breaks down the components of the Wilson and Cleary model, highlighting examples of research in SLE that have examined the relationships between the relevant domains.
Biologic and physiologic variables and symptom status
The relationship between biologic and physiologic variables and symptoms (the patient’s subjective physical, emotional, or cognitive state) is perhaps the most familiar concept to physicians and others involved in the clinical care of SLE. However, even this relationship proves surprisingly complex. Providers who care for patients with SLE intuitively realize this; in some patients, perceived symptoms correlate well with physician and laboratory assessments of disease activity. However, patients frequently experience symptoms in the absence of detectable disease activity, or have no symptoms in the face of obvious disease activity.
Although a patient’s subjective report of symptoms correlates globally with formal disease activity measurements made by a physician, the correlation is only modest. This discrepancy is perhaps best illustrated by examining the growing literature on the validity of self-report measures of disease activity, such as the Systemic Lupus Activity Questionnaire (SLAQ). For many items on the SLAQ, patient reports of symptoms correlate only weakly with physician assessments. For example, for skin disease the correlation coefficient comparing patient-reported symptoms with physician assessments was 0.34, for arthralgia/arthritis 0.50, and for myalgia/myositis 0.27. In a validation study for the SLE Symptom Checklist (SSC), physician assessments of disease activity (as measured by the SLE Disease Activity Index [SLEDAI] or the physician global assessment) correlated only weakly to patient symptoms. Similarly, several studies have documented significant differences between patient and physician assessments of disease activity. For example, in the LUMINA cohort, 58% of patients had a significant disagreement regarding their disease activity compared with their physicians’ assessments.
Given that known biologic and physiologic parameters seem to only modestly affect individual perceptions of symptoms in SLE, what other factors have a role? As depicted in Fig. 1 , a variety of things are postulated to influence the perception of symptoms. In SLE, a few studies have attempted to further investigate these influences. Adams and colleagues found a relationship among psychological factors (stress, depression, anxiety, and anger) and SLE symptoms in a small study of 41 patients, particularly among a group whom they termed “stress responders.” Similarly, in a study that followed 23 patients with SLE prospectively every 2 weeks for up to 40 weeks, Ward and colleagues demonstrated that changes in depression and anxiety scores were correlated with simultaneous changes in patients’ global assessments of their SLE activity. Other studies have also found that assessment of disease status by patients is influenced by their psychological well-being.
Beyond understanding the multidimensional inputs into HRQOL, these findings have broader implications for patient care and medical care. Addressing the symptoms that patients experience requires a comprehensive approach that reaches beyond overt biologic and physiologic parameters. Similarly, in trying to understand the effects of costs associated with SLE, and why these differ significantly among patient groups, factors beyond assessments of disease activity must be considered.
Functional Status
The next central area depicted in the Wilson and Cleary model is functional status. Functional status can be considered broadly as a patient’s ability to perform a variety of activities, and encompasses not only physical function but also social role and psychological function. In Fig. 1 , symptoms are one important influence on functional status, but a variety of other inputs are often present. Again, for clinicians, this may be intuitive; 2 patients with similar SLE symptoms may have vastly different functioning. Social support, levels of helplessness, illness-related behaviors, environment, and access to medical care are just some of factors that may influence functional outcomes.
Decrements in functional status in SLE have been well documented. All domains of function seem to be influenced by the disease, although some seem more affected than others. Reductions in physical function in SLE are substantial compared with individuals with other chronic medical conditions (hypertension, diabetes, depression, myocardial infarction) and the general population, although they seem less severe than in RA. In the LUMINA cohort, Alarcon and colleagues demonstrated that a variety of factors influence physical functioning in SLE beyond disease activity: lower socioeconomic status assessed at baseline predicted poorer physical functioning, as did higher degrees of helplessness, abnormal illness-related behaviors, and lower social support. Similarly, other studies have demonstrated that poor social support was associated with lower functional status.
Social functioning, which is defined by normative behaviors in social situations, is also severely affected by SLE compared with the general population and to those with other chronic medical conditions; impairments in SLE are similar to those in individuals with depression. In addition to higher disease activity, lower socioeconomic status, higher levels of helplessness, abnormal illness-related behaviors, and poorer social support all predict lower social functioning.
Using a novel measure set, valued life activities (VLAs; a wide range of life activities deemed to be important by the individual), that moves beyond the basic functional status items examined in the studies mentioned earlier, Katz and colleagues demonstrated significant impairments in SLE. Discretionary VLAs, such as leisure activities, social activities, and hobbies were more severely affected by SLE than obligatory VLAs, such as basic self-care, driving a car, or using transit. Although disease-related factors played a role, additional factors such as low educational attainment or cognitive impairment also influenced VLA impairment.
Reductions in psychological functioning in SLE are also substantial. Understanding the factors contributing to poor psychological function in SLE is complex, given that the disease itself has neuropsychiatric manifestations with direct effects on mood (eg, cerebrovascular accidents, cortical inflammation, and seizures). Studies evaluating the relationship between disease activity and psychological functioning are mixed, and comparisons are difficult because findings seem to depend on the disease activity measure that was assessed. For example, several studies using the SLEDAI found no significant relationship with the psychological functioning domain of SF-36, although a study using the Mexican version of the SLEDAI did find a relationship. Most, but not all, studies that have used the British Isles Lupus Activity Score (BILAG) or the Systemic Lupus Activity Measure (SLAM) seem to demonstrate some relationship between disease activity and psychological functioning. In the LUMINA cohort, even after disease activity is accounted for, lower socioeconomic status, higher degrees of helplessness, abnormal illness-related behaviors, and poorer social support seem to have a role in psychological functioning.
The Wilson and Cleary model has directionality, implying that biologic and physiologic parameters are among the factors that lead to symptoms, and symptoms are among the factors that lead to decrements in functional status. Although the predominant causal relationships therefore run from left to right in the model, there may be instances in which reverse relationships also exist (eg, depression leading to altered biologic or physiologic variables). Painting a more accurate picture regarding the multidimensional inputs into functional status will require further research; however, the growing literature cited earlier supports the view that a broad-based, multidisciplinary approach is required to characterize and understand functional impairments in SLE.
General Health Perceptions and Overall Quality of Life
As patients subjectively respond to the previous factors discussed in the model (symptoms, functional status, individual characteristics, and the environment), the more global concept of general health perceptions emerges. One of the fascinating aspects of subjective assessments of general health relates to their powerful predictive value. Numerous studies have demonstrated that self-rated health is a predictor of mortality, even when specific health status indicators and other relevant covariates that are known to predict mortality are taken into account.
In SLE, studies have demonstrated that a significant proportion of patients rate their general health as poor. For example, in a study using 3 large observational cohorts, individuals with SLE were more likely to rate their health as poor (47%) compared with individuals with RA (37%) or COPD (40%). Whether or not these ratings are associated with mortality in SLE, as they are in a variety of other chronic health conditions, requires further investigation, although preliminary data from one small study in Brazil found that self-rated health was among the predictors of mortality in a group of 63 patients.
The studies discussed earlier illustrate the validity of the Wilson and Cleary model, and suggest that it provides a useful framework for thinking broadly about the concept of HRQOL in SLE.
Measuring HRQOL in SLE
The previous section illustrates the multidimensional inputs into the concept of HRQOL. With this framework in mind, how should HRQOL in patients be assessed? Several measures have been developed during the last several decades that attempt to measure HRQOL in SLE. However, commonly used instruments cover a variety of different domains ( Table 1 ). Although there are several types of measures that conform to the general rubric of HRQOL, this article focuses on 2 main categories: generic HRQOL measures and SLE-specific measures. Other measures, such as utility-based measures (which incorporate preferences and are commonly used for economic evaluations), individualized measures (which allow patients to weigh the importance of items in their own life), and dimension-specific measures (which focus on a single area of HRQOL such as fatigue or depression) are not discussed here.
| Measures | No. of Items | Domains | Scores Derived | Item Responses | Score Range | Administration | Time to Complete |
|---|---|---|---|---|---|---|---|
| SLE-specific measures | |||||||
| Lupus Quality of Life (L-QoL) | 25 | Overall effect of SLE and its treatment on patient | Count of symptoms | Yes/no | 0–25 | Self-completed | <5 min |
| SLE Symptom Checklist (SSC) | 38 | Checklist of disease and treatment related physical symptoms | Count of symptoms | Yes/no, followed by 4-point response for yes responses | 0–38 | Self-completed | <10 min |
| SLE Quality of Life (SLEQoL) | 40 | 6 (physical functioning, activities, symptoms, treatment, mood, self-image) | Summary score | 7-point response | 40–280 | Self-completed | Not reported |
| Lupus Quality of Life (LupusQoL) | 34 | 8 (physical health, emotional health, body image, pain, planning, fatigue, intimate relationships, and burden to others) | Subscale scores for the 8 domains | 5-point response | Scores are standardized to range 0–100 | Self-completed | <10 min |
| Generic instruments | |||||||
| Medical Outcomes Study Short Form (SF-36) | 36 | 8 (physical function, physical role function, vitality, bodily pain, mental health, emotional role function, social function, general health perceptions) | Subscale scores for the 8 domains. 2 summary scores (Physical and Mental Component Scores) | Mixture of 3, 5 and 6-point response scales | Scores are standardized to range 0–100 | Self-completed to interviewer-administered | 10–15 min |
| Quality of Life Scale (QOLs) | 16 | 5 (material and physical well-being, relationships, social/community/civic activities, personal development and fulfillment, recreation) | Total score | 7-point scale | 16–112 | Self-administered or interview-administered | 5 min |
| European Quality of Life Scale (EuroQoL) | 5 | 5 (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) and VAS for overall general health | 3 scores: a profile (5-digit descriptor indicating extent of problems in each domain), a population preference-weighted index, and VAS | 3-level response and a VAS | Profile score: 5-digit descriptor (lists scores ranging from 1 to 3 for all 5 dimensions, eg, 33,333). Index score: −0.11 to 1 | Self-completed | 2 min |
| Sickness Impact Profile (SIP) | 136 | 2 domains, 12 categories (sleep and rest, eating, work, home management, recreation and pastimes, ambulation, mobility, body care and movement, social interaction, alertness behavior, emotional behavior, communication) | 12 category scores, 2 domain scores and a total score | Respondents check items that describe them on a given day; items weighted to reflect the relative severity of each statement | 0–100 | Self-completed or interviewer-administered | 20–30 min |
| WHOQoL-Bref | 26 | 4 (physical health, psychological health, social relationships, environment) and overall quality of life and health | 4 domain scores, raw scores can then be transformed to 0–100 scale | 5-level response | 0–100 | Self-completed or interview-administered | 10 min |
Generic Instruments
A variety of generic measures are available and several have been validated in SLE ( Tables 1 and 2 ). Generic HRQOL measures generally include a variety of domains. For example, the most commonly used generic HRQOL instrument in SLE, the Medical Outcomes Study Short Form 36 (SF-36), incorporates physical functioning, role limitations because of physical problems, bodily pain, general health, social functioning, mental health, role limitations because of emotional problems, and vitality.
| Measures | Construct Validity | Internal Consistency | Test-retest Reliability | Floor and Ceiling Effects | Responsiveness |
|---|---|---|---|---|---|
| SLE-specific measures | |||||
| L-QoL | `✓ | ✓ | ✓ | ||
| SSC | ✓ | ✓ | ✓ | ✓ | |
| SLEQoL | ✓ | ✓ | ✓ | ✓ | ✓ |
| LupusQoL | ✓ | ✓ | ✓ | ✓ | |
| Generic instruments | |||||
| SF-36 | ✓ | ✓ | ✓ | ✓ | ✓ |
| QOLs | ✓ | ✓ | ✓ | ||
| EuroQol | ✓ | – | ✓ | ✓ | ✓ |
| SIP | ✓ | ✓ | ✓ | ||
| WHOQoL-Bref | ✓ | ||||
Generic instruments have significant advantages but also notable disadvantages. A benefit is that they allow comparison of the HRQOL in one condition to other related conditions or to population norms, something that has been useful in documenting that SLE has similar or worse HRQOL decrements compared with other severe chronic conditions. In addition, many generic instruments have undergone validation testing and may be available in different languages. The major drawback to generic instruments in SLE is that they may not capture symptoms or issues that are specific to the disease, and, therefore, may have reduced sensitivity to detect meaningful changes over time. For example, there is some literature to suggest that the SF-36 is insufficiently sensitive to change in longitudinal studies, and may lack domains that are particularly relevant to a population with SLE, such as fatigue or sleep. In contrast, results from recent clinical trials show that the instrument may respond to change over the short-term, findings that emphasize the need to carefully examine the psychometric properties of an instrument before using it in different demographic groups, regions, or settings.
Generic instruments have been used for some time in observational studies of SLE, but the addition of these measures routinely to clinical trials is a new development. Many recent studies, including trials investigating treatment with dehydroepiandrosterone, mycophenolate mofetil versus oral cyclophosphamide, abetimus sodium, and belimumab have included HRQOL measures (and all used the SF-36 in addition to other measures). These trials demonstrated that generic HRQOL measures may demonstrate responses to treatment that are not necessarily captured with traditional disease activity and damage assessments. As the use of these instruments increases, further information about their psychometric properties and how to interpret improvements or decrements in scores related to specific therapies will likely be forthcoming. Therefore, several groups have recommended the use of HRQOL measures as routine end points in SLE studies in the future.
SLE-specific Instruments
To date, 4 SLE-specific HRQOL instruments are available, although additional measures are in development (see Table 1 ). As opposed to generic instruments, these measures were designed to measure HRQOL among individuals with SLE, and therefore focus on the specific challenges and issues important to patients with the disease. Some were developed with structured input from patients regarding how the disease has affected their lives. For example, McElhone and colleagues performed 30 face-to-face recorded interviews with patients as the first step in developing items for the LupusQoL. Instruments such as this are likely to capture the concepts relevant to individuals with SLE more accurately. However, because notions of HRQOL can vary significantly among persons from different demographic groups or from different countries, further validation work is needed before application in settings where the instruments have not been tested.
As illustrated in Table 2 , preliminary validation work has been done for some of these instruments in defined populations, although further work is needed. Such measures will likely have a place in SLE studies in the future, although as mentioned earlier, their use precludes comparing HRQOL across conditions or in the general population.
Choosing an HRQOL Measure in SLE
The previous 2 sections outline a conceptual overview of HRQOL in SLE and briefly discuss available instruments and their characteristics. This section summarizes the relevant issues in selecting an HRQOL instrument for use in clinical practice or research.
There are 4 questions to consider when selecting an instrument:
- 1.
Are the domains covered by the instrument relevant to the question or use at hand? As illustrated in Table 1 , available HRQOL instruments in SLE cover a variety of different domains. Given the complexity and multiple inputs to HRQOL (see Fig. 1 ), available measures are unlikely to capture all relevant concepts. Increasingly, SLE researchers are using several instruments concomitantly (generic instruments and disease-specific instruments) in clinical trials and population-based studies.
- 2.
Have sufficient validation studies been performed to assure that the instrument is psychometrically sound (valid, reliable, and responsive)? As illustrated in Table 2 , HRQOL instruments currently used in SLE have undergone varying degrees of testing. Even if such testing has been performed, it is important to remember that validation of HRQOL instruments is always a work in progress. A single validation study in a particular demographic group or region does not always seamlessly apply to other populations. Generally, the more validation studies available demonstrating similar psychometric properties, the more likely that the instrument will behave similarly in future applications.
- 3.
Are there floor and ceiling effects that are relevant? A ceiling effect is when individuals with the best score may still have substantial HRQOL impairment that is not captured by the instrument. Alternatively, a floor effect is when patients with the worst score may deteriorate further (see Table 2 ). In some cases, this lack of variability can seriously compromise the usefulness of the measurement.
- 4.
What resources are available to assess HRQOL? All HRQOL instruments are subjective; that is, in attempting to capture the patient’s perspective, they must be reported by the patient. Several methods are available to achieve this objective. Commonly used methods include in-person interviews, telephone interviews, and self-completed questionnaires. Therefore, choosing an instrument entails careful assessment of resources (in-person interviews are most expensive, self-completed questionnaires less expensive, and telephone interview methods somewhere in between) and yield (methods based on in-person and telephone interviews generally have higher response rates, whereas self-completed questionnaires have lower response rates). Attention to whether the instrument has been validated using the chosen administration route is also important (see Table 1 ).
Employment
Although, as indicated at the beginning of this article, work may not be central to the lives of all persons of working age, it is often the portal to activities that are central. For example, it may provide the resources to travel or to partake in hobbies. It is also crucial to the accumulation of assets that can provide for an adequate standard of living in retirement. In the HRQOL scheme developed by Wilson and Cleary, employment would be captured by the functional status domain. Because of the integrative set of skills necessary to sustain employment, it would be categorized in the subdomain of social role participation.
The literature on work loss associated with chronic disease in general emanates disproportionately from medical researchers rather than labor market analysts. The latter tend to be more precise in defining employment in a manner consistent with national unemployment statistics, with the consequence that not all the studies use the same terms to estimate the employment rate and to provide consistent inclusion and exclusion criteria. However, the level of precision may not matter in SLE because the effect of this condition on employment is so great.
Fig. 2 , from the review article by Baker and Pope, summarizes the employment results from 23 studies. In all of the studies, the average age of the persons with SLE was between 34 and 47 years, usually the age range at which employment rates peak because almost all people have completed their education. The late 40s is the age at which most of us have achieved seniority in jobs but have not yet been subjected to age-related job displacement. It is therefore telling that, on average, only 46% of persons with SLE reported being employed. The largest study was from Germany, and reported one of the lowest employment rates. The next 4 largest studies used similar methods and reported employment rates of between 46% and 54%, consistent with the overall results. The overall results, disproportionately affected by the other large studies, indicate that slightly less than half of working age adults with SLE are employed.
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