PASS – A new pass for outcome research

Patient acceptable symptom state (PASS) is defined as the highest level of symptom beyond which the patient considers themselves in a state of well-being.

Research methodology for PASS:

Step 1: Selection of an outcome measuring tools related to the desired outcome (Pain VAS, BASDAI for ankylosing spondylitis, womac for osteoarthritis)

The criteria for selecting an outcome measuring tools should that 

• Its output should be a numerical variable
• It should be able to appropriately measure the disease activity according to the required outcome

Step 2: The patient should be taught to fill the above outcome measuring tool and they should be also asked the yes or no question that is mentioning their satisfaction in continuing in the current symptom scale in the future period. 

The score of the outcome measuring tool will be correlated with the yes or no reply of the patient. A yes by the patient defines the patient to be in remission and the associated score of the outcome measuring tool is defined as the remission score of the patient. A no by the patient defines the patient to be in flare and the associated score of the outcome measuring tool is defined as the flare score of the patient.

The statistical approach used to derive the PASS scores for disease state

The 75th percentage approach: The cut-point corresponding the 75th percentile of the score for improvement in the patient who reported improvement by the anchoring question.Receiver operating characteristic (ROC) curve method: This method allows for choosing the threshold that is the best compromise between sensitivity and specificity for each outcome criterion.

Outcome expected: We could define a disease state-wise scores for an outcome measuring tool.

Application of PASS:

• Used in clinical trials to define their endpoints in terms of PASS scores.
• The development of PASS scores can be used in clinical practice guidelines to taper the drug dose modifications and other interventions.

PASS scores can be used to define the state of diseases in health economics 

• modelling

The disadvantage of PASS: huge sample sizes have to be used to ensure the robustness of the PASS cut points.

-Mr. Aby Paul