Symptom Status and Functional Status Outcomes - Wiley Online Library

Symptom Status and Functional Status Outcomes: Humanistic Outcomes in Obesity Disease Management Mary E. Ropka

Introduction Obesity is a complex, chronic health problem that is associated with increased mortality, morbidity, and health care costs, as well as decreased life quality (1– 6). “The pathway to obesity is a complex journey,” involving biologic and genetic, emotional, social, and cultural factors (7). Changes in the U.S. health care delivery system, including managed care or disease management approaches, necessitate the development of systems that can be used to assess quality of care and demonstrate accountability in the health care of obese populations. Inherent in this is the identification of outcome, intermediate, and process measures (8,9). Disease management outcome measures must meet identified standards for scientific validity, relevance, and feasibility as outlined in the charge to the Team on Developing Obesity Outcomes and Learning Standards (TOOLS) Task Force of the North American Association for the Study of Obesity (NAASO) (10). The purpose of this paper is to recommend obesity disease management outcome measures to assess symptom status and functional status of populations in outcomes research evaluating the effectiveness of the management of obesity (grades I to III).

Clarifying Outcome Measures for Obesity Disease Management Disease management “. . . refers to the use of an explicit systematic population-based approach to identify persons at risk, intervene with specific programs of care, and measure clinical and other outcomes” (11). It is important to keep in mind that many existing clinical outcome measures were

Department of Health Evaluation Sciences, School of Medicine and School of Nursing, University of Virginia, Charlottesville, Virginia. Address correspondence to Mary E. Ropka, Ph.D., RN, FAAN, Division of Health Services Research & Outcomes Evaluation, Department of Health Evaluation Sciences, UVA Health System, Box 800821, [FedEx: Blake Center, 4th Floor, Room 400B], 1224 West Main Street, Charlottesville, VA 22908. E-mail: [email protected] Copyright © 2002 NAASO

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developed for use in population-based epidemiological surveys or clinical trials, and therefore may not be appropriate for monitoring individual patients clinically or for disease management purposes (11). Obesity outcome measures evolved from a singular focus on traditional medical clinical outcomes associated with obesity. They include 1) clinical events, such as myocardial infarction or cerebrovascular accident; 2) biologic or physiological measures, such as hypertension or hypercholesterolemia; and 3) mortality. Encouraged by increased demands of patients for involvement in decisions about their own health care, escalating health care costs, and wider availability of sophisticated computerized information systems, outcomes measures have expanded beyond mortality and morbidity. They now include at least two additional areas: humanistic outcomes and economic outcomes. Humanistic outcomes include 1) symptom status, 2) functional status, and 3) quality of life (QOL), whereas economic outcomes include 1) direct costs and 2) indirect costs. Humanistic outcomes are also referred to as “patient-oriented” outcomes, reflecting their importance to patients. Clarifying Humanistic or Patient-Oriented Outcomes To properly evaluate humanistic (or patient-oriented) outcomes, long-standing confusion regarding first the conceptualization and then the measurement of symptom status, functional status, and QOL must be clarified. They must first be distinguished from each other by clear conceptual definitions. Conceptualization. Symptom status is defined as: “. . . a patient’s perception of an abnormal physical, emotional, or cognitive state” (13). Functional status is defined as “a multidimensional concept characterizing the ability to perform those activities people do in the normal course of their lives to meet basic needs, fulfill usual roles, and maintain their health and well-being” (14). Overall QOL is defined as subjective well-being or satisfaction with life. Symptom status and functional status are distinct from QOL and from each other.

Symptom Status and Functional Status Outcomes, Ropka

Figure 1: Relationships among measures of patient outcomes in a health-related quality of life conceptual model (13). (Reproduced with permission: Wilson IB, Cleary PD. Linking clinical variables with health-related quality of life: a conceptual model of patient outcomes. JAMA. 1995;273:59 – 65.)

The Health Status model proposed by Wilson and Cleary (13,15,16) helps clarify symptom status, functional status, and QOL outcomes while acknowledging the complexity of their inter-relationship (Figure 1). The major factors included in their health status model are 1) biologic and physiological factors; 2) symptom status; 3) functional status; 4) general health perceptions; and 5) overall QOL. The Health Status Model helps to clarify the distinction between symptom status, functional status, and QOL by identifying them explicitly as separate entities and giving clear definitions for each, which enables their separate measurement. They represent a continuum of increasing biologic, social, and psychological complexity. At the biologic end of the continuum, measures are relatively simple, such as albumin or weight, whereas at the other end, measures, such as physical functioning and general health perceptions, are more complex. Wilson and Cleary emphasize that the arrows in their figure indicate dominant relationships and do not imply that other relationships do not exist (13). Biologic and physiological factors, which focus on function of cells, organs, and organ systems, have commonly been conceptualized, measured, and applied in routine clinical practice and clinical research. Examples related to obesity include 1) diagnoses, such as diabetes mellitus and atherosclerosis; 2) laboratory values, such as cholesterol and hemoglobin A1c; 3) measures of physiological function, such as the graded step test; and 4) physical exam findings, such as weight and blood pressure. Measurement. Next, symptom status, functional status, and QOL must be operationalized in terms of how they are measured. These concepts have mistakenly been used inter-

changeably in clinical research and health services research, as well as related publications and presentations. For example, the same instruments, the Sickness Impact Profile (SIP) and Medical Outcomes Study (MOS) Short Form (SF-36), have been reported in different studies to measure health status, functional status, QOL, or health-related QOL. (17,18) In addition, a number of these same instruments combine measurement of symptoms, function, and other aspects of life quality in one instrument and are used in their entirety without distinguishing which concepts are actually being measured by which items or subscales. Understanding overall QOL as a summary measure is also fundamental to sorting out this confusion. General measures of well-being and life satisfaction, in other words, overall QOL, are not as strongly correlated with life circumstances such as symptoms or function as one might expect. An example is the paraplegic who reports his or her overall quality of life as high. Patients change their expectations and aspirations as life circumstances evolve, which may be part of coping or adaptation. Furthermore, as evident in Figure 1, overall QOL is more distant from interventions than symptom status or functional status, and it is influenced by many things. Thus, it may not be as sensitive an outcome measure as symptom status or functional status.

Why Are Symptom Status and Functional Status Essential Outcomes for Obesity Disease Management? Because obesity involves both biologic and behavioral etiologies and management that is largely carried out on a OBESITY RESEARCH Vol. 10 Suppl. 1 November 2002

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daily basis by the patient, symptom status and functional status provide important complements to traditional clinical outcomes measures— clinical events, biologic measures, and mortality. How patients feel—symptom status—and what they do—functional status—are highly valued by patients, their families, and purchasers of health care (19). Symptom status and functional status measures describe or characterize what the patient experiences as a result of obesity and its treatment. They are important because they are closely related to how people with obesity get through life each day. Obesity therapeutic interventions increasingly focus on improving patient function and well-being, in addition to short-term weight loss, decreased adverse clinical events, and lower mortality. Both symptom status and functional status are also related to adherence with other therapeutic interventions. Symptom status and functional status can be equally sensitive or more sensitive to clinically important changes in response to obesity disease management than traditional clinical variables because they are able to detect important patient-oriented differences not tapped by biologic or other traditional clinical outcomes. Studies of the relationship between symptoms and specific dimensions of functional status suggest that symptoms and biologic variables are correlated with function, but do not fully explain function (13,15,16). New or adapted symptom status and functional status measures need to be developed for the following uses: 1) monitoring patient populations for disease management purposes as opposed to those instruments used for screening in population-based epidemiological surveys, such as the Center for Epidemiological Studies–Depression instrument (20), or 2) following the response of individuals in clinical trials, such as the Hamilton Depression Scale (21,22).

Symptom Status Outcomes Symptom Status in Obesity Symptom status, defined earlier as “a patient’s perception of an abnormal physical, emotional, or cognitive state,” expands the focus from specific cells and organs to the entire body, and thus to the person’s experience as a whole. Symptom reports “. . . are expressions of subjective experiences that summarize and integrate data from a variety of disparate sources” (13). Symptoms are best measured by patient self-report and not by family or health-care provider proxy. Evaluation of symptoms and their meaning is related to patient decisions to seek health care, subsequent health care use, and costs of health care. Symptoms commonly associated with obesity include dyspnea, hip and knee pain, low back pain, fatigue, sleep disturbance, and depression. Past approaches to measuring symptom status suffer from several shortcomings when the goal is to evaluate obesity disease-management outcomes, including 1) fit, 2) completeness, 3) impact, and 4) spectrum. In terms of fit, the 44S


symptoms that have been included were not necessarily those that are most relevant to obesity and its treatment. Completeness has been sacrificed because evaluation of symptom status was limited to symptoms that were already part of existing functional status, health status, or QOL instruments regardless of whether they included all symptoms relevant to obesity or side effects relevant to its treatment. For example, SF-36 subscales only address vitality and pain (18). In terms of impact, earlier approaches to measuring symptom status have tended to include only the dimension of severity or intensity. They have neglected to assess other dimensions of the symptom experience—frequency, duration, or impact of the symptom—that reflect how much the symptom bothered the person or how it interfered with his or her life. Some instruments that assess symptoms measure frequency, some measure duration, some impact, and some distress, but few symptom measures consider these characteristics of the symptom experience in combination. Because symptom status, functional status, and QOL are different concepts, any one should not be embedded in a measure of the other so that symptoms, function, and QOL are kept distinct. Finally, symptoms have been evaluated in a limited spectrum of obese patients, most frequently those with morbid obesity and not those with moderate obesity. This does not provide an understanding of the experience nor evaluate the health care outcomes of a large segment of the obesity disease-management population—those with moderate obesity. To address these prior shortcomings and improve evaluation of obesity symptom status, clinimetric factors that should be considered when developing obesity-specific symptom status outcome measures are summarized in Table 1. Potential Strategies to Develop Obesity-Specific Symptom Status Outcome Measures Three potential strategies are identified to assure obesityspecific symptom status outcome measures. Option 1: develop a new condition-specific measure for obesity. Disadvantages of this approach are that it is expensive and timeconsuming, and clinimetric development of instruments for clinical and research purposes is a long-term process and not a short-term event. While this approach may work for the more distant future, it does not provide an obesity outcome measure to meet more immediate needs. Option 2: adapt an existing general (non-obesity) symptom measurement instrument by restricting it to symptoms relevant to obesity. An example of such an instrument is the Memorial Symptom Assessment Scale (MSAS), which was developed to measure symptom status in cancer patients (22). This could be accomplished in a relatively timely fashion. Option 3: use attribute- or dimension-specific subscale(s) that focus on symptoms from emerging obesity condition-specific instruments. Examples of obesity-specific instruments include the 1) Impact of Weight on Quality of Life Questionnaire


Table 1. Clinimetric or measurement considerations: obesity-specific symptom status and functional status

Clinimetric issues Generic- vs. condition-specific or attributed measures Symptom dimensions—severity, frequency, duration, bothersomeness or distress Reporter—patient, family, health care provider Time frame—now, last week, past month Perspective—most severe (toxicity) vs. most common Frequency of measures—burden/cost if too often vs. precision/missing events if too infrequent; set timing vs. event-driven Timing of measures—set interval vs. event-driven Administration mode—mail, phone interview, written, in person oral interview Interpretation of change in outcomes with different response sets— VDS vs. VAS Readability levels/literacy

Time to complete—burden if too long Cultural competence

TOOLS recommended approach for obesity-specific symptom status outcomes*

TOOLS recommended approach for obesity-specific functional status outcomes*

Condition-specific or attributed measures Distress or bothersomeness dimension, if limited to one

Condition-specific or attributed measures Not applicable

Patient self-report

Patient self-report

During the last week or past month

During the last week or past month

Most common or usual for patient

Most common or usual for patient

Need to balance the cost and precision; timing depends on study situation

Need to balance the cost and precision; timing depends on study situation

Set interval

Set interval

Appropriate to study circumstances and research question

Appropriate to study circumstances and research question

VDS

VAS more problematic

Appropriate for study sample VAS response sets difficult for some samples Simple and brief Appropriate for study sample

Appropriate for study sample VAS response sets difficult for some samples Simple and brief Appropriate for study sample

* Should be consistent with other study measures so they can be compared. TOOLS, Team on Developing Obesity Outcomes and Learning Standards; VDS, verbal descriptor scale; VAS, visual analogue scale.

(IWQOL) (23–26); 2) Obesity-Related Well-Being (ORWELL97) (27); 3) Swedish Obese Subjects Intervention Trial Battery (28 –31); and 4) global health-related QOL Measure and Health State Preferences assessment (32). To be used at the subscale level, it is important for the subscale to have been tested clinimetrically to establish reliability, validity, and sensitivity to clinically meaningful changes at the subscale level as well as the scale level. In general, because instrument development is a long and complex process, it is preferable to use or adapt existing instruments rather than to develop them de novo.

TOOLS Recommendations for Obesity Symptom Status Outcome Measurement The TOOLS recommendation at this time is to adapt an existing non-obesity symptom outcome instrument used in other chronic diseases or conditions, such as cancer (Option 2). Based on best evidence, clinical judgment, and patient preference, this should identify and include important obesity-related symptoms, such as dyspnea, lower extremity (hip and knee) pain, low back pain, fatigue/decreased energy, sleep disturbance, anxiety, and depression (33). The MSAS is an example of such an instrument (22). For each OBESITY RESEARCH Vol. 10 Suppl. 1 November 2002

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Table 2. Symptom status: example of adapting the Memorial Symptom Assessment Scale (MSAS) for obesity Instructions: We have listed eight symptoms below. Read each one carefully. If you have had the symptom during the past 3 months, let us know how OFTEN you had it, how SEVERE it was usually, and how much it DISTRESSED or BOTHERED you by circling the appropriate number. If you DID NOT HAVE the symptom, make an X in the box marked DID NOT HAVE. IF YES, How often did you have it?

IF YES, How SEVERE is it usually?

IF YES, How much did it DISTRESS or BOTHER you?

DURING THE PAST THREE MONTHS, Did A Did you have any of the not Almost Very Not little Quite Very following symptoms? have Rarely Occasionally Frequently constantly Slight Moderate Severe severe at all bit Somewhat a bit much Low back pain Joint pain or stiffness (including hips, knees & back) Shortness of breath or difficulty breathing General fatigue, tiredness, weakness Chest pain, pressure, palpitations or other discomfort in the chest Sleep disturbance Anxiety Depression

▫

1

2

3

4

1

2

3

4

0

1

2

3

4

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1

2

3

4

1

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3

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0

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1

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▫ ▫ ▫ ▫

1 1 1 1

2 2 2 2

3 3 3 3

4 4 4 4

1 1 1 1

2 2 2 2

3 3 3 3

4 4 4 4

0 0 0 0

1 1 1 1

2 2 2 2

3 3 3 3

4 4 4 4

symptom that is experienced by the person, the MSAS asks him or her to rate three dimensions: 1) frequency, “how OFTEN did you have it?”; 2) severity, “how SEVERE was it usually?”; and 3) distress, “how much did it DISTRESS or BOTHER you?”. Frequency is rated as rarely, occasionally, frequently, or almost constantly. Severity is rated as slight, moderate, severe, or very severe. Distress is rated as not at all, a little bit, somewhat, quite a bit, or very much. This same MSAS format can be used to evaluate obesity-specific symptoms (See Table 2 for an example). Two alternative recommendations were also considered. First, employ one of the obesity-specific instruments that are currently under development. Even though they have the advantage of being condition-specific, this is suggested as a secondary recommendation because the instruments are all still in the early stages of development. In addition, each has disadvantages. The IWQOL includes a 13-item health subscale (23,24). In addition to being new, the ORWELL97 suffers from limited and unfocused content (27). The Swedish Obese Subjects Intervention Trial Battery is very psychosocial-oriented and lengthy (28). It includes a 9-item General Health Rating Index, 38-item Mood Adjective Checklist, the Hospital Anxiety and Depression Scale, and 20 items from the SIP. Content of the new global healthrelated QOL Measure and Health State Preferences is diverse and lengthy with 55 items (32). Second, when the outcomes assessment goal is to provide in-depth evaluation of one specific obesity-related symp46S


tom, an existing instrument that focuses on that symptom can be used in addition to the core symptom measure. Based on clinical expertise and review of the literature, symptoms relevant to obesity are dyspnea, lower extremity pain, low back pain, fatigue, sleep disturbance, anxiety, and depression. Examples of symptom-specific instruments that should be considered to measure these are listed in Table 3.

Functional Status Outcomes Functional Status in Obesity Like symptom status, functional status is an important point of integration for understanding patient health-related experiences and effectiveness of interventions and is highly valued by patients. Functional status is defined as “. . . a multidimensional concept characterizing the ability to perform those activities people do in the normal course of their lives to meet basic needs, fulfill usual roles, and maintain their health and well-being” (14). Although the same instrument, for example, the MOS SF-36 or the SIP, has mistakenly been reported in prior research to measure both functional status and quality of life, functional status should be distinguished from QOL in that “. . . functional status may be one component of health and quality of life, or a predictor of both. These concepts are not identical. . . ” (51,52). Measures of function “. . . assess the ability of the individual to perform particular defined tasks” (53). Symptom status is


Table 3. Suggested outcome measures for specific symptoms Obesity-specific symptoms

Symptom-specific instrument suggestions

Dyspnea Lower extremity joint (hip and knee) pain

Chronic Respiratory Questionnaire Dyspnea Score (34) Musculoskeletal Outcomes Data Evaluation and Management System (MODEMS) [http://www.aaos.org/wordhtml/outcomes/question.htm] (35) Western Ontario and McMaster Osteoarthritis Index (WOMAC) (36–41) Owestry Low Back Pain Disability Questionnaire (for specialty, high disability) (42) Roland-Morris Disability Questionnaire (for primary care, low disability) (42) MODEMS (35) Schwartz Fatigue Scale (43–45) Profile of Moods States (POMS): Fatigue/Energy Subscale (43) Pittsburgh Sleep Quality Index (46) Medical Outcomes Study (MOS): Sleep Scale (47) POMS: Anxiety Subscale (48) Spellberger Stalt-Trait Anxiety Scale (49) POMS: Depression Subscale (48) Beck Depression Inventory (50)

Low back pain

Fatigue Sleep disturbance Anxiety Depression

different from functional status and can be an important determinant of functional status. A minimum of four dimensions commonly measured in functional status are most relevant to obesity management. They are physical functioning, role functioning, emotional functioning, and social functioning. It is especially important to include those dimensions of functional status that are valued by patients in addition to those important to healthcare providers, employer insurance purchasers, and society. When evaluating obesity disease-management outcomes, past approaches to measuring functional status suffer from shortcomings in three major areas: 1) focus (scope), 2) sensitivity, and 3) completeness. In terms of focus, when instruments such as the SIP, SF-36, or Quality of WellBeing Scale are used in their entirety, their content is not restricted to functional status but includes a potpourri of symptom, function, and health perception scales or items (14,17,53). This results in conceptual confusion and measurement errors. Sensitivity is a problem with some functional status measures because they only assess physical disability, as reflected by Activities of Daily Living or Instrumented Activities of Daily Living scales, and thus fail to detect functional status changes until disability is extreme. Examples include the Barthel Index and Katz Index of Independence in Activities of Daily Living (54,55). Completeness is compromised by instruments that do not reflect the full range of functional status dimensions—physical, emotional, role, and social. To redress these prior limitations and improve future measurement of obesity-specific functional status, clinimetric factors that should be considered are summarized in Table 1.

Potential Strategies to Develop Obesity-Specific Functional Status Outcome Measures Three potential strategies for developing obesity-specific functional status outcome measures are identified. Option 1: develop a new condition-specific functional status outcome measure. This approach has the same disadvantages as discussed for developing a new obesity-specific symptom status outcome measure: cost and timeliness. Option 2: adapt an existing generic functional status instrument to include only those subscales that target the most important obesity-specific functional status dimensions—physical functioning, emotional functioning, role functioning, and social functioning. This approach requires the use of instruments that have been validated at the subscale level. Option 3: adopt the attribution approach suggested by Roland and Morris (56), in which items from a previously validated generic instrument are rewritten with attribution to a specific condition. For TOOLS, the attribution approach adds an appropriate phrase to existing items— “because of your obesity” to the stem statement or “by obesity” to the response set. Both Options 2 and 3 can be accomplished in a timely fashion. TOOLS Recommendations for Obesity-Specific Functional Status Outcome Measurement The TOOLS recommendation to measure functional status as an outcome in obesity disease management is to adopt a combination of the second and third options. For Option 2, select MOS SF-36 subscales that reflect the four functional status dimensions most relevant to obesity—physical, emotional, role, and social functioning (not the SF-12 or SF-20). OBESITY RESEARCH Vol. 10 Suppl. 1 November 2002

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The following MOS SF-36 subscales should be included: Physical Activities; General Mental Health; Role Activities (Physical Factors); Role Activities (Emotional Factors); and Social Functioning (18,57). Neither the Vitality Subscale nor the Pain Subscale should be included as functional status measures because they reflect symptom status rather than functional status. For Option 3, adapt the items in each subscale using the attribution approach. Add the appropriate attribution phrase to each subscale item, “because of your obesity” to the statement and “by obesity” to the response set. In addition, modified instructions indicate that the patient should respond related to his or her obesity or its treatment.

Summary Appropriate evaluation of obesity disease-management outcomes should include symptom status and functional status in addition to the traditional biomedical outcomes of mortality, morbidity, and clinical events. This requires 1) clarifying the concepts symptom status, functional status, and quality of life; 2) adapting or developing self-report instruments that measure symptom status and functional status outcomes and yet meet expected scientific standards of validity, relevance, and feasibility; and 3) finding parsimonious outcomes measures that are appropriate for disease management purposes rather than clinical trials or basic research. References 1. Mokdad AH, Serdula MK, Dietz WH, Bowman BA, Marks JS, Koplan JP. The spread of the obesity epidemic in the United States, 1991–1998. JAMA. 1999;282:1519 –22. 2. Must A, Spadano J, Coakley EH, Field AE, Colditz G, Dietz WH. The disease burden associated with overweight and obesity. JAMA. 1999;282:1523–9. 3. Lean ME, Han TS, Seidell JC. Impairment of health and quality of life using new US federal guidelines for the identification of obesity. Arch Intern Med. 1999;159:837– 43. 4. Yanovski SZ, Yanovski JA. Drug therapy: obesity. N Engl J Med. 2002;346:591– 602. 5. Blair SN, Nichaman MZ. The public health problem of increasing prevalence rates of obesity and what should be done about it. Mayo Clin Proc. 2002;77:109 –13. 6. Whitaker RC. Understanding the complex road to obesity in early adulthood. Ann Intern Med. 2002;136:923–5. 7. McTigue KM, Garrett JM, Popkin, BM. The natural history of the development of obesity in a cohort of young U.S. adults between 1981 and 1998. Ann Intern Med. 2002;136:857– 64. 8. Connors A. The transformation of medicine: the role of outcomes research. Obes Res. 2002;10(Suppl 1):3S–5S. 9. Bolmey A. Outcome measures in the health-care industry: an elusive goal. Obes Res. 2002;10(Suppl 1):10S–13S. 10. Wolfe A. Economic measures. Obes Res. 2002;10(Suppl 1): 58S– 62S. 11. Epstein RS, Sherwood LM. From outcomes research to disease management: a guide for the perplexed. Ann Intern Med. 1996;124:832–7. 48S


12. Lyons H, O’Mahoney L. The Measurement and Management of Clinical Outcomes in Mental Health. New York: Wiley; 1997, p. 36. 13. Wilson IB, Cleary PD. Linking clinical variables with healthrelated quality of life. A conceptual model of patient outcomes. JAMA. 1995;273:59 – 65. 14. Leidy NK. Functional status and the forward progress of merry-go-rounds: toward a coherent analytic framework. Nurs Res. 1994;43:196 –202. 15. Wilson IB, Cleary PD. Clinical predictors of declines in physical functioning in persons with AIDS: results of a longitudinal study. J Acqur Immune Defic Syndr. 1997;16:343–9. 16. Wilson IB. Clinical understanding and clinical implications of response shift. Soc Sci Med. 1999;48:1577– 88. 17. Bergner M, Bobbitt RA, Carter WB, Gilson BS. The Sickness Impact Profile: development and final revision of a health status measure. Med Care. 1981;19:787– 805. 18. Ware JF, Snow KK, Kosinski M, Gandek B. SF-36 health survey: Manual and Interpretation Guide. Boston: Health Institute, New England Medical Center; 1993. 19. Fontaine KR. Weight loss and health—relate quality of life. Am J Man Care. 2001;7:926 –7. 20. Radloff LS. The CES-D Scale: a self-report depression scale for research in the general population. Appl Psychol Meas. 1977;1:385– 401. 21. Potts MK, Daniels M, Burnam A, Wells KB. A structured version of the Hamilton Depression Rating Scale: evidence of reliability and ease of administration. J Psychiatr Res. 1990; 24:335–50. 22. Portenoy RK, Thaler HT, Kornblith AB, et al. The Memorial Symptom Assessment Scale: an instrument for the evaluation of symptom prevalence, characteristics and distress. Eur J Cancer. 1994;30A:1326 –36. 23. Kolotkin RL, Head S, Hamilton M, Tse CK. Assessing Impact of Weight on Quality of Life. Obes Res. 1995;3:49 – 56. 24. Kolotkin RL, Head S, Brookhart A. Construct validity of the Impact of Weight on Quality of Life Questionnaire. Obes Res. 1997;5:434 – 41. 25. Samsa GP, Kolotkin RL, Williams GR, Nguyen MH, Mendel CM. Effect of moderate weight loss on health-related quality of life: an analysis of combined data from 4 randomized trials of sibutramine vs. placebo. Am J Man Care. 2001; 7:875– 83. 26. Kolotkin RL, Crosby RD, Williams GR, Hartley GG, Nicol S. The relationship between health-related quality of life and weight loss. Obes Res. 2001;9:564 –71. 27. Manucci E, Ricca V, Barciulli E, et al. Quality of life and overweight:the Obesity Related Well-being (Orwell 97) Questionnaire. Addict Behav. 1999;24:345–57. 28. Sullivan M, Karlsson J, Sjo¨stro¨m L, et al. Swedish obese subjects (SOS)—an intervention study of obesity. Baseline evaluation of health and psychosocial functioning in the first 1743 subjects examined. Int J Obes Relat Metab Disord. 1993;17:503–12. 29. Larsson U, Karlsson J, Sullivan M. Impact of overweight and obesity on health-related quality of life—a Swedish population study. Int J Obes Relat Metab Disord. 2002;26:417– 24.


30. Kaukua J, Pekkarinen T, Sane T, Mustajoki P. Healthrelated quality of life in WHO Class II-III obese men losing weight with very-low-energy diet and behavior modification: a randomized clinical trial. Int J Obes Relat Metab Disord. 2002;26:487–95. 31. Ryden A, Karlsson J, Persson LO, Sjo¨ stro¨ m L, Taft C, Sullivan M. Obesity-related coping and distress and relationship to treatment preference. Br J Soc Clin Psychol. 2001;40: 177– 88. 32. Mathis SD, Williamson CL, Colwell HH, et al. Assessing health-related quality-of-life and health state preference in persons with obesity: a validation study. Qual Life Res. 1997; 6:311–22. 33. Ropka ME, Spencer-Cisek P. PRISM. Priority Symptom Management Project Phase I: assessment. Oncol Nurs Forum. 2001;28:1585–94. 34. Guyatt GH, Townsend M, Keller J, Singer J, Nogradi S. Measuring functional status in chronic lung disease: conclusions from a randomized control trial. Respir Med. 1991; 85(suppl B):17–21;discussion 33–7. 35. Anonymous. Choosing the Right AAOS Outcomes Questionnaire. Chicago, IL: American Academy of Orthopedic Surgeons, 2000. 36. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol. 1988; 15:1833– 40. 37. Ehrich EW, Davies GM, Watson DJ, Bolognese JA, Seidenberg BC, Bellamy N. Minimal perceptible clinical improvement with the Western Ontario and McMaster Universities osteoarthritis index questionnaire and global assessments in patients with osteoarthritis. J Rheumatol. 2000;27:2635– 41. 38. McConnell S, Kolopack P, Davis AM. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC): a review of its utility and measurement properties. Arthritis Rheum. 2001;43:453– 61. 39. Angst F, Aeschlimann A, Steiner W, Stucki G. Responsiveness of the WOMAC osteoarthritis index as compared with the SF-36 in patients with osteoarthritis of the legs undergoing a comprehensive rehabilitation intervention. Ann Rheum Dis. 2001;60:834 – 40. 40. Angst F, Aeschlimann A, Stucki G. Smallest detectable and minimal clinically important differences of rehabilitation intervention with their implications for required sample sizes using WOMAC and SF-36 quality of life measurement instruments in patients with osteoarthritis of the lower extremities. Arthritis Rheum. 2001;45:384 –91.

41. Jones JG, Leighton F. Comparison of WOMAC with SF-36 for OA of the knee or hip. Ann Rheum Dis. 2002;61:182–3. 42. Fairbank JC, Couper J, Davies JB, O’Brien JP. The Oswestry low back pain disability questionnaire. Physiother Res Int. 1980;66:271–3. 43. Schwartz AL. The Schwartz Cancer Fatigue Scale: testing reliability and validity. Oncol Nurs Forum. 1998;25:711–7. 44. Schwartz AL, Meek P. Additional construct validity of the Schwartz Cancer Fatigue Scale. J Nurs Meas. 1999;7:35– 45. 45. Schwartz AL, Meek PM, Nail LM, et al. Measurement of fatigue determining minimally important clinical differences. J Clin Epidemiol. 2002;55:239 – 44. 46. Buysse DJ, Reynolds CF, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatr Res. 1989;28: 193–213. 47. Hays RD, Steward AL. 14. Sleep Measures. In: Steward AL, Ware JF, eds. Measuring Functioning and Well-Being: The Medical Outcomes Study Approach. Durham, NC: Durham University Press; 1992:449. 48. McNair DM, Lorr M, Droppleman LF. Profile of Mood States. San Diego, CA: EDITS Press; 1971. 49. Speilberger CD, Gorusch RL, Lushene RE. Manual for the State-Trait Anxiety Inventory. Palo Alto, CA: Consulting Psychologists Press; 1983. 50. Beck AT, Steer RA, Garbin MG. Psychometric properties of the Beck Depression Inventory: twenty-five years of evaluation. Clin Psychol Rev. 1988;8:77–100. 51. Murdaugh C. Patient outcomes research: examining the effectiveness of nursing practice. The State of the Science Conference. Rockville, MD: United States Department of Health and Human Services Publications; 1991, pp. 91– 6. 52. Strickland OL. Challenges in measuring patient outcomes. Nurs Clin North Am. 1997;32:493–512. 53. Kaplan RM, Bush JW. Health-related quality of life measurement for evaluation research and policy analysis. Health Psychol. 1982;1:61– 80. 54. Fortinksy RH, Granger CV, Seltzer GB. The use of functional assessment in understanding home care needs. Med Care. 1981;19:489 –97. 55. Katz S, Akpon CA. Index of ADL. Med Care. 1976;14(suppl 5):116 – 8. 56. Roland M, Morris R. A study of the natural history of back pain. Part I: development of a reliable and sensitive measure of disability in low-back pain. Spine. 1983;8:141– 4. 57. Jenkinson C, Stewart-Brown S, Petersen S, Paice C. Assessment of the SF-36 version 2 in the United Kingdom. J Epidemiol Community Health. 1999;53:46 –50.


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