Patient-centric sampling is a design requirement, not a device category. Programs that treat it as a shopping decision pick hardware first, usually something small that photographs well, and discover the mismatch after money is committed to tooling and print. That sequence fails late and it fails expensively.
This paper sets out what the requirement commits a program to, what the published evidence says about patient burden and analytical performance, who carries the validation burden, and how one collection decision propagates through every downstream element of a kit.
What the term commits you to
The Patient Centric Sampling Interest Group describes patient-centric sampling as obtaining high quality biological samples from humans at any time and in any location, with the patient’s needs and comfort at the front of the design. The matrices in scope are broad: blood, plasma, serum, urine, stool and saliva. So are the device categories: samplers, lancets, swabs and urine collection systems. Supera Fulfillment is a sponsor of PCSIG.
Read the definition again and notice what it does not say. It does not say fingerstick. It does not say home. It does not say dried blood. Those are implementations. Patient-centric sampling is the requirement those implementations are trying to satisfy, and several of them satisfy it without a kit at all.
A patient-centric option can be a fingerstick at a retail pharmacy, a collection at a workplace clinic, or a mobile phlebotomist at a kitchen table. All three reduce patient burden. Only one of them needs a kit shipped to a house.
It is also not a route around validation, and it is not cheaper by default. Lower volume means tighter tolerances, more rejected samples and more re-collection. Re-collection is the line item that quietly decides whether a program pencils, and it rarely appears in the model that got the program approved.
What the evidence says about patient burden
The strongest comparison currently published is a Labcorp head-to-head study, Collier and colleagues, released in late 2025, with 41 participants. It evaluated four upper-arm collection technologies alongside fingerstick and standard venipuncture.
Three findings are worth carrying into a program decision.
- No single technology was superior. Correlative results were similar across the upper-arm devices, and selection came down to the intended use population rather than to device performance.
- Reported pain ran from 0.5 to 1.8 out of 10 for upper-arm collection, against 1.5 for venipuncture and 2.5 for fingerstick.
- Roughly 72 percent of participants preferred upper-arm collection. Zero percent preferred fingerstick.
That last figure is the one most programs have not internalised. Fingerstick is the default because it is inexpensive, familiar and easy to source. On the patient experience it is the worst of the three options tested, on both pain and stated preference. If burden is the reason the program exists, defaulting to fingerstick works against the reason the program exists.
The corollary is that no upper-arm device wins on published performance alone. Anyone presenting one as clinically superior to the others is going beyond what the comparison supports. The decision is made on intended use, on the population, and on what the cleared indications actually permit for the configuration in question.
Where the matrix breaks
The single most useful proof point for anyone arguing that capillary blood is not simply venous blood in a smaller tube comes from Labcorp’s own vacuum-assisted device study, published in Diagnostics in mid-2025 with 42 participants. Mean collected volume was 538 microlitres, yield was 97.6 percent, and reported pain was 0.39 out of 10.
Seventeen of nineteen analytes met CLIA limits against venous comparison. Glucose and potassium did not.
Seventeen out of nineteen is a good result and a dangerous one. It is an excellent hit rate unless one of the two failures is your analyte, in which case the program does not work and no amount of packaging design will rescue it. This is why the analyte list has to be settled before the device is chosen, not after.
Microsampling and the hematocrit problem
Dried formats carry a separate and frequently misunderstood issue. Volumetric absorptive microsampling is often described as having solved the hematocrit problem that affects dried blood spots. It solves half of it.
VAMS fixes the volume half. It does not fix the recovery half. The published record on this is not ambiguous:
- The manufacturer has stated that hematocrit did not influence recovery. Independent validation work found otherwise.
- An everolimus evaluation at hematocrit values of 0.20, 0.45 and 0.65 showed bias running from roughly minus 20 percent to plus 31 percent.
- At least one study concluded that VAMS performed worse than dried blood spots in its particular context.
- Extraction solvent choice, water against organic, drives a large share of the outcome.
None of that makes microsampling unsuitable. It makes it a method development question rather than a procurement question. A dried format commits the program to an extraction protocol, and the extraction protocol has to be developed and validated against the actual hematocrit range of the intended population.
Who owns the validation burden
The UK recommendations for the validation and adoption of capillary blood testing within the routine clinical laboratory, published in Annals of Clinical Biochemistry in May 2026, state the position plainly. Accredited laboratories that intend to report capillary results have to run their own comparison studies. Most assay manufacturers do not list capillary blood in their instructions for use. The validation burden therefore sits with the laboratory, not with the device maker.
The practical consequence for a program sponsor is that the laboratory is a gate, not a downstream vendor. A laboratory that has not agreed to validate, and has not scheduled the work, is a laboratory that cannot report results from the kit being designed. Bring the laboratory lead into the room before artwork is commissioned.
On regulatory status, treat every claim as the manufacturer’s statement rather than a settled fact. Cleared indications, intended use and market authorisation vary by configuration and by territory within a single product line, and a device cleared for professional use is not automatically cleared for unsupervised collection by a lay user. Get the status in writing, for the exact configuration, for the exact market, from the manufacturer.
What the collection decision does to the kit
A collection decision is not a component choice. It is the first link in a chain where each element is determined by the one above it:
Matrix and volume, then device, then tube or substrate, then stabiliser, then fill volume, then temperature requirement, then return path, then outer packaging and marking.
This is why late device changes are so costly. Swapping the device after artwork approval changes the tube. The tube changes the stabiliser. The stabiliser can change the temperature requirement. The temperature requirement changes the return path, and the return path changes the outer packaging, the marking and often the carrier service. A change that looks like a single line on a bill of materials rewrites the second half of the program.
The branch with the largest downstream consequence is liquid against dried. Liquid generally carries a stabiliser, a fill volume tolerance and frequently a temperature requirement on the return leg. Dried generally removes the temperature requirement and replaces it with an extraction and recovery question owned by the laboratory. Neither is simpler. They are differently complex, and the complexity lands on different teams.
A sequence that holds up
- Define the analyte list and name the reporting laboratory.
- Confirm the assay runs on the intended matrix at the volume a real person produces on a cold morning, not the volume on the device datasheet.
- Confirm the laboratory will validate, and on what timeline.
- Select the device against the intended use population and the cleared indications, not against photographs.
- Fix the stabiliser and the fill volume tolerance.
- Derive the temperature requirement from the stabilised sample rather than from habit.
- Design the return path and confirm the shipping classification it falls under.
- Only then commit artwork, tooling and print.
Steps one through three are where programs are actually won or lost, and they are the three most often compressed because they produce nothing anyone can photograph.
When not to build a kit
If patient burden is not the binding constraint on the program, do not build a kit. A kit solves access and burden. It does not solve enrolment, it does not solve adherence on its own, and it does not solve a marketing problem.
If the analyte fails on the intended matrix, the program does not exist yet, regardless of how far the packaging design has progressed.
If the laboratory will not commit to validation, the program does not exist yet either.
Patient-centric sampling is worth doing where burden is the thing standing between a patient and a result. It is not worth doing because a device is appealing, or because a competitor launched one.
Related reading: what patient centric sampling actually means covers the fit question in shorter form. Capillary collection or venipuncture covers the choice once self-collection is established as a fit. DBS and VAMS microsampling covers the dried formats in detail, and how to choose a preservation medium covers what stabilises the sample after it leaves the patient.
