WWW-Proficiency Testing

In the olden days, WWWWW was not a sign of a stuck "W" key, and was not an aberration of www.  It was the journalist code for :who, what, where, when, and why". 
Proficiency Testing (aka EQA) exists in two formats: Regulated - required and often from a required source, and Voluntary - selected for internal reasons.  In most countries PT/EQA is primarily voluntary, in large part because there is no regulation and equally important accreditation is spotty and infrequent. 
There is not only room for both formats,  at the individual laboratory level, the best solution is probably a combination of the two. 
We usually don't have a lot of influence or decision making over the Regulated structure, but we have tons of choice for the Voluntary.

I want to focus on www - who, what, and why, for Voluntary Accreditation - although maybe not in that order.

Why.
Voluntary PT provides a process for quality monitoring, competency testing, and continuing education.  Three very good reasons to be having PT in place in your laboratory. 
Quality monitoring and competency testing roll come together.  If an individual technologist is allowed to test the PT sample in a manner consistent with the laboratory's routine procedure, then performance on PT relates to competency.  If the PT procedure deviates from the routine, then we call that a "waste of time".

If a laboratory is performing around 1 PT sample for every 1000 clinical samples, PT has sufficient power to detect system error.  If the ratio is closer to 1:2500 then the utility of system error detection is near nil. 
For the smaller laboratory, PT reviews are often the only consistent and regular access to continuing education material.

Monitoring PT is a useful and easy quality indicator.  Is someone noticing and informing others when performance is on-target?  Is someone noticing and informing other AND following up when it is not? 

Of all the reasons for doing PT, probably the worst (at the individual level) is for "inter-laboratory comparison".  This is only useful for bureaucrats and statisticians.  Inter-laboratory comparison is probably the single greatest killer of laboratory quality that was every created.  All it does is promotes "gaming" (repeat testing, over-testing,  deceptive practices, like sending PT samples to reference laboratories). 
If you are performing the tests competently then does it matter if other laboratories are doing the same or not?  If you have opportunities for improvement, does it make it better if some other laboratories are having the same problems.  "I know our results are junk, but so are those of 5 other laboratories".

What.
PT samples should look like and more importantly act like true clinical samples.  This is especially true in microbiology and chemistry, and immunohistochemistry. 
Every time I give a presentation I get the same comment.  "You should disguise all your samples so that they have a patient name and medical insurance number.  That way we wouldn't know they come from CMPT.  Actually there were studies on enteric PT done in Japan in the '80s that looked at that.  At that time no significant differences in performance were detected.  But there is almost nothing that would prevent each laboratory to consider a disguising program.
In my experience, lyophilized samples rarely look like and more importantly act like true samples. 
But maybe I am biased.
To the extent possible, having a PT program for each type of sample and each test is desirable.  Usually it is not possible.


Who.
This is the beauty of volunteer PT.  You get to pick your provider. 
1- Do they provide you with the samples you need? 
For larger laboratories, you probably will need to work with 2 or 3 providers to get the volumes that you need.
2 - Will they provide you with extra samples so that you can do competency assessment for multiple technologists at the same time?
3 - Will they ensure their shipping dates, so that someone in the laboratory knows when to expect the samples?
4 - Are they an inspected group (certified or accredited) so that you can have confidence they are working at the same level of quality and competence as you are, or at least at the level that you would want to be?
5 - Is the quality of their continuing education material at the level that will be beneficial in your laboratory>
6 - Is their costing reasonable?

So, for me the right answer is, even if you are not an accredited laboratory, if laboratory quality is important to you, then  PT offers valuable quality monitoring and education.  If you work in a small or intermediate laboratory, you probably can get all the support that you need from one supplier.  If you are working in a larger laboratory, there are clear advantages to working with 2 or maybe 3 suppliers to get the samples and education information that you need.

If laboratory quality is not very important to you, then probably you are not visiting this site.