Primer on Musculoskeletal Outcome Measures and Instruments

APTA Vision statement

Transforming society by optimizing movement to improve the human experience

Evidence Based Practice (EBP): patient values

are unique preferences, concerns and expectations each patient brings to a clinical encounter and which must be integrated into clinical decisions if they are to serve the patient

Evidence Based practice (EBP)

integration of:

• current best research evidence

• your clinical expertise

• patient values

formulation of an answerable clinical question:

PICO

• patient (or population, or problem)

• intervention (or comparison)

• outcomes

the triple aim

better case, better health, and lower costs

guide to physical therapist practice

Outcomes research: guide to physical therapist practice

“PT determines expected outcomes and engages in outcomes data collection and analysis… statistical reports for internal or external use”

Traditional research

• impairments: ROM, strength

• physiological parameters: HR, radiographs, etc

• function/performance: gait speed, functional performance, return to work

outcomes research

• covers what the patient thinks of the results of the care given

• meant to enhance evaluation, not replace the usual methods

barriers to outcomes research

• attitudes, paradigms, lack of understanding

• time pressures

• unseen value by some *time vs productivity”

“End Result” Idea

the common-sense notion that every hospital should follow every patient it treats, long enough to determine whether or not the treatment has been successful, and then to inquire ‘if not, why not'?’ with a view to preventing similar failures in the future

Ernest Armory Codman, M.D.

• “End result Idea”

• founder of joint commission on accreditation of healthcare organizations

• Codman’s Pendulums

• Codman’s Paradox

• Codman’s triangle

MIPS

Medicare program that awards providers for tracking outcomes

• initial

• discharge pairings

Why use an outcome measure

• impairments measures alone are inadequate

• enhances patient care → assists in goal setting

• substantiates improvement in QOL from our interventions

• may improve shared/clinical decision making

• communication

  • patients

  • physicians/surgeons/referral sources

  • research/standardization for intra-group comparisons

  • scrutiny by 3rd party payers/recognition of external benchmarks

  • ensuing “pay for performance” models

    • standardized outcome measures are one indicator

What makes a quality outcomes instrument

components:

• content

• psychometric (clinimetric) properties

  • reliability, validity, responsiveness

• clinical utility

Content

Type:

• generic, condition-specific, patient specific

• clinician based (CBO)

• patient reported (PRO)

Scale:

• what measures or questions make up the instrument

• how are they scored

Interpretation

• do higher scores indicate a better outcome

• do certain scores pertain to excellent or poor outcomes

clinician based outcomes (CBO)

• measured by clinician

• joint ROM, strength, alignment, stability

• considered “objective” inferring functional ability

patient reported outcomes (PRO)

• patient perceptions of sx’s, abilities, and quality of life

• considered more “subjective”

• emphasis now greater on patient perceptions

psychometric properties: validity

extent to which the instrument measures what it is supposed to measure

psychometric properties: reliability

ability of the instrument to measure something the same way twice (or repeatedly)

psychometric properties: responsiveness

ability of the instrument to change as the status of the patient changes (referred to as “sensitivity to valid change”)

Validity

• Construct (refers to items like pain or disability)

  • Divergent

  • Convergent

• Content (refers to comprehensiveness of scale)

  • Face

• Criterion (correlates with some “gold standard”)

  • predictive

  • concurrent

divergent

two similar tools do not correlate highly if they measure different attributes (i.e. social/emotion vs physical)

convergent

high correlation between two different tools measuring similar attributes

face

inferred from content experts

Reliability: internal consistency

how consistent are the questions in measuring the same outcome

Reliability: test-retest

how close are the results of an instrument given to the same patient on two different occasions

Reliability: inter-observer

how closely does observer 1 agree with observer 2 using the same instrument on the same patient

responsiveness

another psychometric property

• what is the functional status of a patient at a given point in time (baseline)?

• has a patient’s functional status truly changed

• AND, is this change important

• MDC or MCID

MDC: minimal detactable change

error estimate of change of an instrument

MCID, minimal clinically important difference

minimal change in score, indicative of change in function, that is truly important to a patient

MCID

• first described in 1989 (Jaeschke et al)

  • “the smallest difference.. which patients perceive as beneficial and which would mandate,,,, a change in patient management”

• Vary widely, no standard as how to calculate MCID

  • 9 different calculation methods

Global Rating of Change (GRoC)

MDC and MCID

Floor and Ceiling effects

useful measures must provide room for clients to demonstrate improvement or deterioration

ceiling effect

“top out” on scale, achieving normal function when some disability remains

floor effect

“bottom out” on scale, unable to detect a decline in status

patient friendly clinical utility

• time to administer

• clear, concise, easy to understand questions

• patient comfort in answering questions

clinician friendly clinical utility

• staff vs. self administered

• staff effort/cost in administering, recording, and analyzing

• scoring time (30-60 seconds)

Individual Common Barriers

• time

• knowledge

• resources

• competence

• attitude

organizational common barriers

• time and cost

• policy

• culture

individual common facilitators

• positive attitude

• flexibility

• practicality

external common facilitators

• access to resources

• support from colleagues and organization

• guidance in selection, administration, scoring and interpretation

WHO internal classification of Function (ICF) model

Which outcome measure to use?

the WHO ICF framework provides direction and options for choosing a variety of outcomes measures to capture multiple constructs or characteristics

Visual Analog Scale (VAS)

• 100 mm vertical or horizontal line

• continuous line, replaced by continuous boxes

• self—administrated, easy to administer/score

• reliability: test-retest (.71-.99)

• Validity: correlations with McGill Pain Questionnaire, Numeric Pain Rating scale: .30-.95

• Limitations: elderly and less literate populations and errors associated with photocopying/scoring

• Interpretability: score >30mm equal t or greater than “moderate” pain or score > 54mm equal to or greater than “severe” pain

• Responsiveness: MDC 30 mm

Patient Specific Functional Scale (PSFS)

• type: PRO, patient specific

• client asked to identify up 3 to 5 activities at initial visit before their examination

• scale: rates ability to complete each one on 11 pt. scale

  • 0 = unable to perform

  • 10 = able to perform with no problem

• time to administer: 5-15 minutes

• psychometrics: MDC and MCID: 3 points

• comment: not advocated for between-client comparsions

• may be one of most responsive of all health-related quality of life tools