Reading POCTS - RT4
Point of Care Test kits (POCT) - Level 1 Certification
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.
Let's start with how to read POCTs
WHAT POCT RESULTS LOOK LIKE
POCT result are made up of a series of lines that develop when a specimen is introduced to the strips. To read the test is simple. You are looking for missing test lines. If a test line is missing, the specimen likely contains drug and/or drug metabolite.
Reading POCTs is easier when some basic rules are followed.
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.
WHY WAIT 5-MINUTES - THE WINDOW OF ACCURACY
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.
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.
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.
RECORD AN IMAGE OF THE POCT
After reading a POCT result, you may want to consider taking a picture of the POCT with a copy of the donor's ID card or a copy of the result form. The definition of reliability is the ability to rely on the result you provide. Without a copy of the POCT result, there is no evidence that a POCT was read correctly or even performed.
IMPORTANT: Images of non-negative results sent to the lab, can be discarded once the lab report is received provided chain of custody is maintained.
Keep a look out for cheaters
This workbook does not cover specimen collection and you should refer to your collector training for all collection procedures. avoided if this rule is followed. This section is designed to help you spot suspect donors and understand what can happen.
LOOK AT THE LINES
Every time a donor walks out of the bathroom, look at the temperature and lines. What you should see over time is a consistent line development. The lines should be "underdeveloped" at this point. In fact, the lines should remain underdeveloped until the sample begins to cool. Test lines can take up to five minutes to develop.
If you notice a sample that has fully developed lines at 98 degree, you may want to consider collecting another sample.
Case: From time to time, we receive calls from collectors that claim the specimen was negative, however when sent to the lab, it confirms positive for one or more drugs at high levels. This happens when the donor performs a partial sample submission. The donor places a small amount of negative urine (or other liquid) in the cup and allows the lines to develop before providing an authentic sample. Newer collectors can be caught by this technique.
Solution: Some collectors use a primary collection cup and transfer the sample to the test cup after collection. This method prevents pre-testing. If that is not an option, using a SVT strip (specimen validity test) may help identify old urine or non-biological substances.
LOOK AT THE SAMPLE
Some donors try to present fake urine or other substances as their specimen. If you have collected specimens for years, you probably have a good eye for suspect samples. But if you are newer to testing, this may not be a honed skill yet.
END OF READING POCTS