Reading POCTS

Point of Care Test kits (POCT)

Reading a POCT is simple...in theory.  If there is a red test line present beside the drug abbreviation and there is a red control line present beside the letter C, the result for that assay is negative. If the red test line is missing, then it is positive.

 

Simple enough right? Well, if you have run POCTs before then you know it is not always that simple.  This section is designed to help you better understand what is going on and what you can control.

The Basics on how to read POCTs​

POCT result are made up of a series of lines that develop when a specimen is introduced to the strips. Reading a POCT is simple. You are looking for missing test lines. If a test line is missing, the specimen likely contains drug and/or drug metabolite.

Interpretation of Results

RULE ONE
WAIT 5-MINUTES 
- THE WINDOW OF ACCURACY 


This is the most important rule that will help eliminate a vast majority of the issues POCT users experience. So many problems can be avoided if this rule is followed.

If you do not have the ability to wait 5-minutes on every test, there are some precautions that can be taken to help minimize result inaccuracy. But keep in mind, if you do not wait 5-minutes, you will very likely reduce the accuracy of your testing program.

IMPORTANT: Certain assays may run slower for certain donor samples than others. These outlier tests can cause false readings. Always wait at least 5 minutes to read positives. The window of accuracy for urine POCTs is 5-minutes after collection yet no longer than 55-minutes. For oral POCTs the greatest accuracy is 10-minutes after sample introduction to the POCT strips yet no longer than 60-minutes.  

IMPORTANT ORAL: In oral fluids collection and testing, NEVER ask the donor to spit directly into the POCT housing. Spitting directly into the POCT housing can flood the test, cause invalid, false positives and even false negative results.

 

The Window of Accuracy for most urine POCTs 5-55 minutes after a donor sample has contacted the POCT strips.  Oral Fluid POCT generally take longer to flow and may alter this timeline by 5 minutes. (10-60 minutes post introduction).  Reading POCT results outside of this window can result in reduced POCT accuracy.

RULE TWO
READ ONE POCT STRIP AT A TIME

Attempting to read a multi-assay POCT quickly can sometimes be challenging. Trying to read one assay when staring at all of the assays can create an optical illusion of a test line when the test line is actually missing. We have noticed that the occurrence of this optical illusion appears to worsen when reading POCTs all day. It can also get worse when:

 

  • All or most of the test and control lines are light.

  • The missing test line is a center strip, not a first or last strip. 

A good method to use when reading a POCT with light lines is to read each strip one at a time. Using two pieces of paper, block out all but one POCT strip at a time as shown in the example to the right.

 

IMPORTANT: Any line, regardless of intensity should be considered negative.

RULE THREE
READ THE RESULT, DON'T GUESS AT IT

 

If after RULE ONE and RULE TWO, you remain unsure about the result, it is best to send the sample to a lab for confirmation testing. If not using a confirmation lab, consider retesting the original sample using a new POCT and wait 10 minutes before attempting to read the second POCT result.

IMPORTANT: NEVER GUESS at results. Make sure you are confident with the interpretation before recording the POCT outcome.