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Outcomes Multi-systemic Impact: Fibromyalgia

Outcomes Multi-systemic Impact: Fibromyalgia. George A Wells Department of Epidemiology and Community Medicine University of Ottawa. Fibromyalgia.

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Outcomes Multi-systemic Impact: Fibromyalgia

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  1. OutcomesMulti-systemic Impact:Fibromyalgia George A Wells Department of Epidemiology and Community Medicine University of Ottawa

  2. Fibromyalgia • chronic musculoskeletal disorder characterized by widespread pain, exquisite tenderness at specific anatomic sites and other clinical manifestations such as fatigue, sleep disturbance and irritable bowel syndrome (Bradley and Alarcon) • ACR 1990 criteria for classifying patients with fibromyalgia: • widespread pain for at least 3 months (pain in left and right sides of body; pain above and below waist; and axial skeletal pain) • tenderness in at least 11 of 18 ‘tender points’

  3. Fibromyalgia … • Controversy: • medicalization of unrelated symptoms • syndrome (occurring with other diseases) • defined disorder • Controversy: • What are the most appropriate outcome measures?

  4. Outcome Measures • Types of outcome measures (Fibromyalgia) • Choosing outcomes • Development and selection of outcomes • Overall response criteria • Minimal clinically important difference • Low disease activity state

  5. Outcome Measures • Types of outcome measures (Fibromyalgia) • Choosing outcomes • Development and selection of outcomes • Overall response criteria • Minimal clinically important difference • Low disease activity state

  6. Types of Outcome Measures(Fibromyalgia) Karjalainen K, et al Multidisciplinary rehabilitation for fibromyalgia and musculoskeletal pain in working age adults Cochrane Collaboration Review 2003 Busch A, et al Exercise for treating fibromyalgia syndrome Cochrane Collaboration Review 2002 Rossy LA, et al A meta-analysis of fibromyalgia treatment interventions Ann Behav Med. 1999

  7. Types of Outcome Measures … Constructs: • Pain • Tender points • Physical function • Global well being or perceived improvement • Self efficacy • Fatigue and sleep • Psychological function • Quality of life

  8. Types of Outcome Measures … Pain • visual analogue scale • ordinal scale • pain drawings • Regional Pain Scale (RPS) (Wolfe, J Rheumatol 2003)

  9. Types of Outcome Measures … Tender points • pain threshold of tender points using dolorimetry • tenderness to thumb pressure

  10. Types of Outcome Measures … Physical function • Self-reported physical function • FIQ Physical Impairment subscale • FHAQ • Musculoskeletal performance • grip strength • hip and knee extension strength • sit and reach test • Cardiorespiratory fitness • submaximal or maximal treadmill or cycle ergometer tests • 6 minute walk

  11. Types of Outcome Measures … Global well being or perceived improvement • physician rated change • FIQ total score

  12. Types of Outcome Measures … Self efficacy • Arthritis Self-efficacy Questionnaire

  13. Types of Outcome Measures … Fatigue and sleep • FIQ fatigue subscale • sleep VAS

  14. Types of Outcome Measures … Psychological function • FIQ subscales for depression and anxiety

  15. Types of Outcome Measures … Quality of life / Generic Functional Status • Short Form 36 (SF36) • Sickness Impact Profile (SIP) • Health Assessment Questionnaire (HAQ)

  16. Fibromyalgia Impact Questionnaire (FIQ) • brief 10-item self-administered instrument • measures • physical functioning • work status • depression • anxiety • sleep • pain • stiffness • fatigue • well-being (Burckhardt, Clark, Bennett, J Rheumatol 1991)

  17. Were you able to: a. Do shopping b. Do laundry with a washer and dryer c. Prepare meals d. Wash dishes/cooking utensils by hand e. Vacuum a rug f. Make beds g. Walk several blocks h. Visit friends/relatives I. Do yard work j. Drive a car [0 Always; 1 Most times; 2 Occasionally; 3 Never]

  18. Of the days in the past week, how many days did you feel good? 1 2 3 4 5 6 7 • How many days in the past week did you miss work because of your fibromyalgia? 1 2 3 4 5 • When you did go to work, how much did pain or other symptoms of your fibromyalgia interfere with your ability to do your job? • How bad has your pain been? • How tired have you been? • How have you felt when you got up in the morning? • How bad has your stiffness been? • How tense, nervous or anxious have you felt? • How depressed or blue have you been? [Questions 4 – 10 assessed using a VAS]

  19. Fibromyalgia Health Assessment Questionnaire (FHAQ) Are you able to (over the past week): a. bending b. dressing c. wash body d. getting in and out of car e. vacuum f. stand up from chair g. reach overhead h. run errands [0 Without any difficulty; 1 With some difficulty; 2 With much difficulty; 3 Unable to do] (Wolfe et al, J Rheumatol, 2000)

  20. Outcome Measures • Types of outcome measures (Fibromyalgia) • Choosing outcomes • Development and selection of outcomes • Overall response criteria • Minimal clinically important difference • Low disease activity state

  21. Choosing Outcomes • objective measurements (validated and accepted to represent appropriate efficacy criteria) • reduced or reversed disease progression • improved quality of life • reduced mortality • clinical global impression (physician, patient) • improved symptomatology of patient • biochemical measures (assessing underlying disease state)

  22. Patients desire the following… 1) to live as long as possible [death] 2) to be normally functioning [disability] 3) to be free of pain, psychological, physical, social and other symptoms [discomfort] 4) to be free of iatrogenic problems from treatments [drug s/e] 5) to remain solvent [destitution]

  23. Identifying the best outcomes … • influence physicians’ decision • combination of outcomes that’s most practical and useful • hard measurement • change in endpoint that would be clinically significant

  24. Identifying the best outcomes …influence physicians’ decision Outcome measurement procedures in routine rheumatology outpatient practice in Canada / Australia ‘How often do you serially use the following assessment techniques for longitudinally monitoring the efficacy of antirheumatic drug therapy in your adult fibromyalgia outpatient practice?’

  25. Identifying the best outcomes …influence physicians’ decision Never Occasionally Usually Always Canada Quality of sleep 11% 11% 28% 50% Fatigue 13% 13% 29% 45% No. tender points 17% 15% 29% 39% Skinfold tenderness 47% 25% 19% 9% Australia Quality of sleep 18% 8% 42% 32% Fatigue 21% 14% 43% 23% No. tender points 38% 22% 30% 10% (Bellamy J Rheumatol 1998, 1999)

  26. Outcome Measures • Types of outcome measures (Fibromyalgia) • Choosing outcomes • Development and selection of outcomes • Overall response criteria • Minimal clinically important difference • Low disease activity state

  27. Criteria for Development and Selection of Outcomes Comprehensive (content validity) - includes appropriate components of health Credibility (face validity) - appears sensible and interpretable Accuracy (criterion validity) - consistently reflects true clinical status of patients Sensitivity to change (discriminant validity) - detects smallest clinically important difference Biological sense (construct validity) - matches hypothesized expectations when compared with other indirect measures

  28. Health Measurement • Reliability • Validity • Sensitivity to Change

  29. Reliability Reflection of the amount of error, both random (mechanical inaccuracy, measurement mistakes) and systematic, inherent to any measurement Determines how reproducible is the scale under different conditions

  30. Reliability The reliability coefficient expresses the proportion of the total variance in the measurements (denominator), which is due to true differences between subjects (numerator)

  31. Reliability • Reproducibility • Test-retest reliability • Intra-rater reliability • Inter-rater reliability • Internal consistencyof a scale (correlation among items composing an instrument)

  32. Reliability: Reproducibility • Intra-class correlation (ICC) (based on ANOVA) • Pearson’s r • Kendall’s index of concordance • Kappa coefficient • Bland and Altman

  33. Reliability: Reproducibility • Other considerations: • Observations as fixed factor • test always done by same observers • same items completed by all • Observations as random factor • observer varies

  34. Reliability: Reproducibility • Other considerations (cont’d): • Observer nested within subject • several subjects evaluated by several observers • no observer common to more than one subjects • One-way ANOVA • subject as grouping factor • multiple observations within each cell as ‘within-subject’ factor

  35. Reliability: Reproducibility • Other considerations (cont’d): • multiple observations k • multiple items on questionnaire • multiple observers • repeated use of an instrument

  36. Reliability: Internal Consistency • Represents the average of the correlations among all items in the measure • All the items should be ‘tapping’ different aspects of the same attribute • items should be moderately correlate with each other • each should correlate with the total scale score

  37. Reliability: Internal Consistency • Item-total correlation • checks homogeneity of scale • correlation of individual item with scale score omitting that item • Pearson correlation (working rule: >0.2) • Split-half reliability • splits scale in half, each half is correlated with the other • Spearman-Brown • Kuder-Richardson 20 • scales with dichotomous items • Cronbach’s aplha • scales with ordinal items • should be >0.70 but <0.90 (item redundancy)

  38. Reliability: Improving IT • Reduce error variance • observer training • elimination of extreme observers • improve scale design • Increase true variance • introduce items resulting in performance nearer middle of scale • modify descriptors on the scale • Increase number of items • as long as items not perfectly correlated

  39. Validity Determine the degree of confidence we can place on inferences made based on the scores from the scale

  40. Validity • Content • cover all domains of interest • sufficient number of items • inferred from experts • Criterion • test against a ‘gold’ standard • Concurrent • gold standard and the new instrument are applied at the same time • Predictive • gold standard is applied in the future

  41. Validity • Construct • if no gold standard exists • based on conceptual definition of construct to be measured • defines hypotheses of what should or should not correlate • Correlational Convergent • instrument tested should correlate with other methods that measure same concept Divergent • instrument should not correlate with other methods that measure different themes

  42. Validity • Construct(cont’d) • Factorial analysis • examines how items measure one or more common themes • analysis forms the questions into groups or factors that appear to measure common themes with each factor distinct from the others • Multi-trait multi-method analysis • method for considering convergent and discriminant validity simultaneously

  43. Validity • Evaluation using: • Correlations • Receiver operator characteristic (ROC) curves • 2x2 tables (sensitivity and specificity)

  44. Sensitivity to Change Ability of an instrument to detect small but clinically important clinical Particularly important where subjective reports of health status is one of the primary outcomes of the trial

  45. Sensitivity to Change • t-test • compares means at baseline and follow-up • Effect-size • relates changes in mean score (from baseline to follow-up) to the standard deviation of baseline score • ROC Curve • Evaluate how a given change score can discriminate between patients who improve from those who do not

  46. FIQ (Burckhardt et al, J Rheumatol 1991) [evidence of reliability and validity] Reliability: test-retest reliability correlations for FIQ items ranged from 0.56 to 0.95 Content validity: assessed by calculating percent missing data: 11% washing by hand item, 20% yard work item, 38% job working items Construct validity: (1) correlational analysis comparing FIQ items/scales to corresponding ones of AIMS: physical functioning item 0.67; pain 0.69; depression 0.73; anxiety 0.76 (2) correlational analysis comparing FIQ items with measures of symptom severity: AIMS impact analog (0.17 to 0.48), AIMS syndrome activity (0.28 to 0.83) and tender points (0.14 to 0.74) (3) factor analysis to determine if items of physical functioning loaded on single factor (eg. 10 items of FIQ loaded on same factor)

  47. FIQ … (Dunkl et al, J Rheumatol 2000) [responsive to perceived clinical improvement] Sensitivity to Change: Patient Global Improvement FIQ mean (sd) Improved 34.11 (17.48) Unchanged 46.92 (15.44) Worsened 57.92 (15.23) (Wolfe et al, J Rheumatol 2000) [FIQ systematically underestimates functional impairment by its handling of activities not usually performed]

  48. 6 Minute Walk (6-MWT) (Pankoff et al, J Rheumatol 2000) [not a valid predictor of cardiorespiratory fitness; sensitive to change; related to FIQ score] Sensitivity to Change: Before After Exercise Exercise p-value 6-MWT, m 487 (75) 565 (58) <0.001 PVO2, ml/kg/min 19.6 (4.5) 21.4 (4.8) 0.001 FIQ Total 47.9 (12.1) 38.0 (12.9) 0.012 FIQ Phys 3.1 (1.7) 2.3 (1.9) 0.0.62 Validity: Correlation of change scores: 6-MWT, PVO2 (r=0.081) 6-MWT, FIQ Total (r=0.592) 6-MWT, FIQ Phys (r=0.245)

  49. Generic versus Specific The use of generic and specific quality of life measures in fibromyalgia patients (Wolfe et al, J Rheumatol 2000) Instruments • Generic: SF-36, HAQ, MHAQ, IHAQ • Specific: FIQ, FHAQ Methods • FM patient (FIQ: Boston 1928, San Antonio 233, US multicenter 333, Beer Sheva 100; HAQ National Data Bank for Rheumatic Diseases 1438; SF-36 Wichita 760) • Rasch analysis (based on item response theory) Results • no functional assessment questionnaire works well • FIQ underestimates functional impairment by handling activities not usually performed • developed FHAQ (subset of HAQ) with appropriate metric propertiesand should function well; need to assess sensitivity to change

  50. Outcome Measures • Types of outcome measures (Fibromyalgia) • Choosing outcomes • Development and selection of outcomes • Overall response criteria • Minimal clinically important difference • Low disease activity state

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