Clinical Trials - Sensitivity, Specificity, Validity & More.

When it comes to issues and complaints of the human body, the musculoskeletal system, and movement apparatus, we at BodyLab, Osteopathy and Physiotherapy, Rehabilitation and Training Zurich are the pros.

Whether with or without a doctor's referral, patients come to us hoping for our help and support.

First, our mission is to pinpoint exactly where and in which structure the issue lies. Medical diagnoses often only describe the general area (or not even that). For instance, a lumbar spine syndrome or lumbago merely tells you that there is trouble, discomfort, or pain in the lower back. Similarly, epicondylitis (tennis elbow) says nothing about its root cause. The issue could be muscular (raising the question of which muscle and where exactly), in the tendon, or at the bone-tendon junction. The examples are endless...

An examination always starts with an in-depth anamnesis: capturing your subjective issues and pain. Where is the pain, when does it trigger, what relieves it or feels good? Is it unilateral or bilateral? Are there radiating sensations, paresthesias? What is the timeline and progression since it started? Was there a triggering event like trauma or overload? What do your daily activities, job, and hobbies look like, and what can you still do versus what is no longer possible? Previous illnesses, injuries, surgeries, and nutritional habits are also of key interest.

In addition, we look at your social and family history (family background, stress-to-capacity ratio of your system), whether medications are necessary or being taken, and we screen for yellow and red flags—all crucial points to uncover, as we will see later.

During this very process, the osteopath or physiotherapist is already formulating various hypotheses based on their deep knowledge and clinical experience.

Through clinical reasoning, functional and movement examinations, and various diagnostic tests, the hypotheses and complaints gathered during the anamnesis are objectified.

As the old saying goes, "If you measure nonsense, you get nonsense." Therefore, it is absolutely vital to use the right, adequate tests, otherwise they are completely useless. Let us break this down for you.

To understand this, imagine a comparison: If you went fishing in a lake (like Lake Zurich) with a wide-meshed net, you would only catch very large fish or perhaps none at all, leading you to believe there are only big fish in that lake. Which, of course, is false. The net simply wasn't sensitive or valid enough for that lake to catch the smaller fish.

Therefore, after the anamnesis, sharp clinical reasoning must guide our thinking:

• What do I want to measure?

  Am I measuring/testing correctly?

  Do I have the ideal measuring instrument?

• Sensitivity / Specificity / Validity

-> Note: It is essential to work with the hypothesis from the anamnesis!!

Measuring instruments and orthopedic or manual clinical tests can be categorized by several key criteria:

1. Sensitivity

2. Specificity

3. Validity

4. Reliability

This is why a comprehensive anamnesis followed by a working hypothesis (therapeutic diagnosis) is so immensely important to select the right clinical test!

Sensitivity

The sensitivity (also known as the true positive rate) of a diagnostic test tells us how likely a positive test result is in a person who actually has the issue. More precisely, it shows the proportion of affected patients in whom the condition is actually detected by the test.

The higher the sensitivity of a test, the more reliably it detects the condition.

Specificity

The specificity of a test indicates how likely a negative test result is in healthy individuals (without the disease or injury).

So, it gives the probability that those who are healthy and do not suffer from the condition are correctly identified as healthy by the test.

Validity

Validity tells us whether a test actually measures what it is designed to measure. A test is valid when it successfully targets and measures the intended variable.

Reliability

Reliability represents the accuracy and consistency of a test. This means whether a test would yield the same result when repeated under identical conditions (reproducibility).

A test is reliable when repeated applications produce the highest possible similarity, ensuring the result is not just a product of chance.

Objectivity

Objectivity refers to how independent the test results are from external conditions and distorting third-party factors.

Responsiveness

This is the sensitivity to change. It determines the ability of a measurement to detect important clinical changes over time—essential for tracking your therapeutic progress!

 Note: Higher sensitivity (towards 100%) is only achieved by reducing thresholds; however, this comes at the expense of specificity!!

As you can easily see, isolated, disconnected clinical tests make little sense and yield no real results or insights. This is a major pitfall for inexperienced therapists! Furthermore, too many tests can provoke and irritate injured structures, which might prevent a clear result from being determined.

Thus, the right diagnostic tests should be selected based on the hypothesis formulated during the anamnesis and clinical reasoning—and they must be executed correctly. This also means a therapist must know the strengths and limitations of a clinical test, and what its purpose is! Is it positive when pain is triggered? Or is an abnormal range/play of motion a positive sign? Or is a diminished or absent reflex a positive sign?

Clinical tests should also be performed in the correct sequence to ensure optimal interpretation.

Clinical Tests: Optimal Sequence and Process

1. Screening Test (High Sensitivity)

   -> to rule out pathology when they are negative

2. Validating Test (High Specificity)

   -> A negative result should mean that the cause is indeed not present

3. Excluding Test (High Specificity)

4. Provoking or Reducing Test

5. Mechanical Test

At the start, a test with high sensitivity and specificity for the respective structure should be used to see if there is an issue. This should be followed by a test with high validity to target that exact structure! Excluding or provoking tests complement the examination, and mechanical tests verify the results.

Scientific Studies of Medical Clinical Tests

As therapists, we believe in constantly evaluating and critically questioning our own thinking and actions.

Literature continuously features studies and publications testing the accuracy and validity of clinical tests. A gold standard on manual examination tests is the book "Orthopedic Physical Examination Tests: An evidence-based Approach" by Chad E. Cook and Eric J. Hegedus.

You should always verify, control, and document your results through objectification. With a little practice and experience, this takes no time at all!

Here is our selection of highly practical tests for various issues—perfect for daily therapeutic practice:

Goniometer: For measuring Range of Motion

Muscle Function Testing: Manual measurement of muscle strength

Visual Analog Scale (VAS): For pain assessment, for example

Coping Strategies Questionnaire: To capture pain coping mechanisms

Short-Form McGill Pain Questionnaire:To evaluate pain

Disabilities of the Arm, Shoulder and Hand (DASH or Quick DASH): Assessing arm complaints and capabilities

Shoulder Pain and Disability Index: Assessing shoulder complaints

Berg Balance Scale: An insightful test for balance

POMA Tinetti Test: To identify fall risk

Dynamic Gait Index: Assessing balance while walking

Timed Walking Tests: Objectively measuring locomotion

Timed Up and Go Test: Rising, walking with a turn

Sharp Purser Test: Checking upper cervical spine stability

Borg Scale: How strenuous is this for you? Measuring subjective exertion

6-Minute Walk Test: Has performance improved?

The 3-Minute Step Test: The ultimate fitness check

Conconi Test: Determining aerobic capacity

Goal Attainment Scale (GAS): Objectively measuring subjective goals

Chedoke McMaster Stroke Assessment: Post-stroke evaluation

Trunk Impairment Scale: Trunk stability post-stroke

You can find more practical clinical tests on the website of the IGPTR Interest Group Physiotherapy Rehabilitation.

Through objective measurements, therapy results and progress can be clearly tracked and documented. Changes that might go unnoticed by you or your therapist can be captured through adequate testing.

To recap: Carefully consider which clinical tests or measuring instruments you want to use for which specific issue. These tests are not universally valid for every single problem!

Test results are not set in stone; they are continuously reassessed, even during treatment. This ensures therapeutic interventions are constantly evaluated and adapted through retesting and close observation of your progress!

As you can see, the human body and manual medicine are complex—but that is what makes it so exciting. It is absolutely worth choosing an engaged, highly competent therapist.

Because, as we know: if you measure nonsense, you get nonsense.

If you need us, we are here for you!

Your BodyLab Team, your specialists for physical injuries

Osteopathy and Physiotherapy | Rehabilitation and Training

Zurich Altstetten

References

Orthopedic Physical Examination Tests: An evidence-based Approach

Chad E. Cook, Eric J. Hegedus

2008 by Pearson Education Inc., Upper Saddle River, New Jersey 07458

IGPTR Interest Group Physiotherapy Rehabilitation