Why Chiropractic Research

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Why Chiropractic Research ?

• To improve the science of chiropractic
• To improve the profession of chiropractic
• To add to mankinds store of knowledge

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Handling Uncertainty

• So, clinical observations should be based on
  sound scientific principles, including ways to
  reduce systematic and random errors.
• These principles are as important to clinicians
  who wish to make the best clinical decisions as
  they are to researchers who will produce the
  evidence.

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Figure 4.2
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Bias vs. Chance
Figure 1.2
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Reliability and Validity

• Reliability is consistency
• Lack of reliability is a problem with random
  error
• CHANCE
• Validity is TRUTH
• Lack of validity is a problem with systematic
  error
• BIAS

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Reliability and Random Error (chance)

• Observer (inter and intra)
• Subject
• Instrument

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Validity and Systematic Error (bias)

• Observer
• Subject
• Instrument

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Measurement Scales and Types of Variables

• Categorical
• Nominal (sex, blood type)
• Ordinal (ranked)
• Continuous (BP, Temp)
• Interval
• Ratio

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Scales of measurement are commonly broken down
into four types

• (1) nominal,
• (2) ordinal, (3) interval, (4) ratio.

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FUNDAMENTAL PROPERTIES OF MEASUREMENT SCALES

•  
• DIFFERENCE
• Tells only that one object differs from another
• MAGNITUDE
• Tells not only that one object is different from
  another, but also what objects contain more of
  the underlying construct than others. The
  intervals between adjacent units on the scale
  might not be equivalent.
• EQUAL INTERVALS
• Tells exactly how much more or less of the
  underlying construct the objects possess. The
  intervals between adjacent units on the scale are
  equivalent.
• TRUE ZERO POINT
• Tells how much (in the absolute sense) of the
  underlying construct an object possesses.

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Prevalence and Incidence

• Prevalence proportion of a defined population
  that has a condition at a given point in time
  (cross-sectional study)
• Incidence proportion of a defined population
  that develops a condition over a defined period
  of time. (longitudinal study)

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Powering the RCT

• Pilot RCT 5-10 participants per group
• Research question re study methods
• Full Scale RCT usually 40 or more per group
• No magic number
• Depends on effect size, variability, other
  factors
• Research question re treatment effectiveness
• P-values
• Statistically significant if the p-value is lt
  0.05
• More stringent if plt0.01

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Observational Studies

• Not designed to answer cause effect questions
• So why not just do RCTs?
• Unethical unless less-invasive studies indicate
  plausible association
• RCT methodology sometimes a difficult fit
• Usual care vs. a lab setting
• Treating a condition vs. optimizing health
• Outcomes measures how to measure better than
  okay
• Dose/response

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Cross-sectional studies

• Exposure and Outcome assessed at the same time
• Cannot determine chronology
• Useful as early study to investigate phenomena
• A made-up example Surveyed people under
  chiropractic care engage in more vigorous forms
  of exercise than do people not under chiropractic
  care
• What can we conclude?

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Summary

• Sample size affects the probability of detecting
  a difference if there is one
• Sample size affects the probability that a
  difference between samples reflects a real
  difference in the underlying population, not just
  a random occurrence
• All studies and all kinds of studies comprise the
  evidence base

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Clinical vs Basic Research

• Basic investigates physiological mechanism(s) by
  which chiropractic works WHY and HOW
• Clinical investigates actual effects on
  patients IF, WHEN and WHOM
• Both are necessary but each requires specialized
  skills to conduct.

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Evidence base congruent with our practice and
philosophy
Refined RCTs
Pre-exp./preliminary
Current
Other Observational
Case Reports
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To build a stronger baseWhat works best for
whom?

• Case reports on chiropractic care
• Observational studies
• Population based
• Practice based
• Preliminary and pilot studies to refine questions

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What do we need to see in case reports?

• Publication in indexed peer-reviewed journals
• Reports of chiropractic care
• Details on techniques
• Details on frequency and duration
• Use of outcome assessments
• Reliable, valid, responsive
• Measure the outcome of interest

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Levels of evidence
Meta-
Analyses RCTs Other Experimental Quasi-Experimenta
l Observational Case reports/Clinical observations
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OUR levels of evidence
Meta-Analyses RCTs Other Experimental Quasi-Experi
mental Observational Case reports/ Clinical
observations
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Evidence-Based Practice definitions

• . . . integrating individual clinical expertise
  with the best available external clinical
  evidence from systematic research.

(Sackett, 1996)
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Another definition. . .

• the conscientious use of current best evidence
  in making decisions about the care of individual
  patients

(ORourke, 1997)
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So
What is EVIDENCE?

• Informationfacts!
• not opinions
• not beliefs
• not theories or philosophy

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Use of chiropractic chief complaints

• Over 94 (closer to 99) of chiropractic
  patients chief complaints involve
  musculoskeletal pain, usually spine-related back
  pain, neck pain and headache. (Hurwitz et al
  1998 Hawk, Long et al 2000)

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Efficacy Studies of Chiropractic

• Efficacy means that it works under
  idealcontrolledconditions
• Randomized controlled trials are the gold
  standard for assessing efficacy

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Problems with our evidence base

• Reductionist model of health
• RCTsreductionist model developed for
  pharmaceuticals
• Lack of observational studies
• Chiropractic does not equal SMT

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Definitions

• Clinical Outcome
• A change in health status after exposure to a
  health care delivery system
• Outcomes Measures
• a procedure or method of measuring a change in
  patient status over time
• Evaluates effectiveness of treatment
• In a broad sense, assesses quality of care

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Outcomes Definitions

• An outcomes-based clinical setting has two
  essential elements
• Outcomes assessment Collection and recording of
  information relative to health processes
• Outcomes management Using information in a way
  that enhances patient care.

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What do outcomes measures measure?

• different types of measures
• clinical
• health status
• quality-of-life
• work/role
• health care utilization
• patient satisfaction

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Clinicians Uses of Outcome Measures

• Evaluate effect of care over time
• Indicate point of maximum therapeutic improvement
• Uncover problems related to care (e.g.
  non-compliance)
• Document improvement to patient, Dr. and 3rd
  parties

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Outcomes criteria

• Utility is it useful?
• Reliability is it dependable?
• Validity does it do what it is supposed to?
• Sensitivity can it identify patients with a
  condition?
• Specificity can it identify those that do not
  have the condition?
• Responsiveness can it measure differences over
  time?

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General Health vs. Condition Specific Measures

• General measure relevant to individuals rather
  than specific condition
• Specific measure that is tailored to a
  particular condition
• Both are necessary for a complete picture

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Patient Satisfaction Questionnaires

• Becoming the quality yardstick
• Can be general or specific

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Case-management

• Outcomes should be measured at appropriate
  intervals during case management, depending on
  nature of the condition, and patient progress.

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Summary

• Measure the outcome of your care.
• It is relatively easy with established
  instruments.
• Gives a more accurate assessment than
  seat-of-the-pants.
• You are going to have to do it anyway.

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p-values (pprobability)

• A statistical value that indicates the
  probability that the observed pattern is due to
  chance alone
• How confident we can be in the conclusion
• this result was significant at plt0.05
• Statistically speaking, and all other things
  being equal, we could expect this result to occur
  by chance no more than 5 times in every 100
  trials
• Example Test 100 coins by flipping each one 100
  times
• One coin comes up heads 73 times
• We suspect this is not an ordinary fair coin
• It is possible for an ordinary coin to get this
  result by chance
• Want to know the probability that a fair coin
  would result 73/100 heads
• How confident are we that this is not a fair coin?

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Determinants of power

• Define what constitutes a true difference
• Determine acceptable levels of Type I and Type II
  errors
• ? in one means ? in the other (tradeoff)
• Calculate the necessary sample size
• Recruit, allowing for losses
• This should be thoroughly described in any
  Methods section!

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The power of a RCT

• The probability of correctly concluding that A is
  not equal to B
• If there is a difference, the probability that
  you will statistically detect it
• 1 - p(failing to detect a true difference aka
  Type II error)
• Sample size needed to power a RCT must be
  calculated a priori, and depend upon
• Expected or clinically important difference
• Acceptable p-value (Type I error probability)
• Acceptable power (1 Type II error probability)

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Sample size calculations

• When a small difference between groups is
  considered clinically important
• A larger sample size is needed
• Setting the significance at .01 instead of .05
• This is increasing the rigor of the study
• Less willing to accept Type I error
• A larger sample size is needed
• To increase the odds of recognizing an actual
  difference (lower the Type II error)
• This is increasing the power of the study
• A larger sample size is needed

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Once again

• Sample size affects the probability of detecting
  a difference between groups if there is one
• Sample size affects the probability that a
  difference between samples reflects a real
  difference in the underlying population
• Not just a random occurrence

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Propositions

• Propositions state the nature of the relationship
  between variables (concepts).
• An hypothesis is a statement about the expected
  relationship between two or more concepts that is
  based on a theory and that can be tested.

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Chiropractic Proposition I

• Between subluxation and health
• The gt the quantity, quality, severity of
  subluxations, the lt health.

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Chiropractic Proposition II

• Between adjustment and subluxation
• The gt the quantity, (etc) of adjustment, the lt
  subluxation.

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Chiropractic Proposition III

• Between adjustment and health
• The gt the quantity, (etc) of adjustment, the gt
  the health.

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Chiropractic vs. Spinal Manipulation

• Chiropractic is a profession
• Study requires sociologic, historic, economic and
  health services methods
• Spinal manipulation is a family of treatment
  procedures
• Study requires epidemiologic and physiologic
  methods

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Chiropractic Theory and Clinical Epidemiology

• Subluxation assessment performance
• Adjustment treatment performance
• Health outcome performance

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Basic Principles

• Populations vs. samples
• Bias (systematic error)
• Chance (random error)

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Populations and Samples
Figure 1.3