Cost per reportable result: a worksheet for lab reagent quotes

To compare lab reagent quotes, work out each one’s cost per reportable result: what you’ll pay, delivered, for the tests you’ll use or lose from its packs, plus any controls and calibrators bought separately, divided by the patient results you’ll report. Dividing a pack’s price by its tests assumes every test becomes a patient result. Some go to controls, calibration and repeats, and any still in a pack when it expires are lost.

Where a pack’s tests go

Unless your lab follows an equivalent procedure that CMS has approved, CLIA requires controls for nonwaived testing at least once each day you test patients. A quantitative test needs two control materials of different concentrations, and a qualitative test needs a negative and a positive control. Some specialties have their own control rules, and the manufacturer’s instructions or your lab’s own procedure may call for more. Controls are tested the same way as patient specimens, so each one uses a test. Their results must meet your lab’s criteria, and the manufacturer’s where they apply, before you report patient results. Repeating a run after a failed control uses more tests. 42 CFR 493.1250 and 493.1256.

Calibration can use tests too. For each test system the rules apply to, CLIA requires calibration at least as often as the manufacturer recommends, and calibration verification using at least a low, a middle and a high value. Verification is due at least every six months. It’s also due whenever a complete change of reagents is introduced, unless your lab can show that changing reagent lots doesn’t affect the range used to report patient results and doesn’t adversely affect control values. Controls are run again before patient testing resumes after a complete change of reagents. 42 CFR 493.1255 and 493.1256. So an order that arrives as two lots can mean an extra calibration verification.

Reagents must be labeled with their expiration date, and CLIA bars using them past it. Testing must also follow the manufacturer’s instructions. 42 CFR 493.1252. Tests left in a pack once its expiration date has passed are lost. If those instructions limit how long a reagent stays stable once it’s opened or mixed, a pack you can’t finish in that time loses the rest of its tests too.

What to ask for on each quote

Ask every supplier for the same terms, in writing:

• Manufacturer, catalog number and tests per pack
• Price per pack, with freight and any charges for cold shipping
• Minimum order
• Dating on arrival, as the minimum time to expiration you’ll accept
• Whether the order ships as one lot
• Whether controls and calibrators are included or quoted separately

If the quotes are for different catalog numbers or pack sizes, ask your lab director to confirm that each one is validated for your test before you compare costs. Our guide to clinical lab supply backorders explains why the same manufacturer and catalog number from another source needs no new validation work. The quote comparison checklist covers delivered totals and unequal packs.

Example: a lower price per test that costs more per result

In this illustrative example, a lab runs a quantitative test on weekdays, with 10 patient samples and two controls a day, so it uses 12 tests a day. The test’s instructions say an opened pack is stable for 28 days, which is 20 run days for this lab. Two quotes arrive for the same reagent in two pack sizes. The lab director has confirmed both are validated for the test, both prices are delivered, and both ship with more dating than the lab needs.

Over four weeks of 20 run days:

A 120-test pack lasts 10 run days, so Quote A loses nothing. A 300-test pack would last 25 run days at 12 tests a day, but its 28 days end after 20, so 60 tests are discarded with every pack. Quote B is 60 cents less per test and 30 cents more per reportable result.

The lab’s volume decides which quote costs less. At 15 patient samples a day, the lab uses 17 tests a day and finishes a 300-test pack in under 18 run days, before its 28 days end. Nothing is discarded, and Quote B costs $3.40 × 17 ÷ 15 = $3.85 per reportable result against Quote A’s $4.00 × 17 ÷ 15 = $4.53.

This example leaves out calibration, repeats and what the lab pays for control and calibrator materials. The worksheet below counts them.

Cost per reportable result worksheet

Fill in one copy for each quote, for the same test and the same period. To count the tests lost, take the tests in each pack and subtract the ones you’ll use before it expires or its opened stability ends.

Cost per reportable result: one quote, one test

Test and supplier: ______
Manufacturer, catalog number, tests per pack: ______
Validated for this test (lab director): ______
Delivered price per pack, with freight: ______
Delivered price per test (pack price ÷ tests): ______
Minimum order and lots per order: ______
Dating on arrival: ______
Stability once opened or mixed: ______

Period: ______
Run days: ______
Patient samples per run day: ______
Controls per run day: ______
Calibration and verification tests: ______
Expected repeats: ______
Controls and calibrators bought separately,
  delivered, for the period: ______
Tests used: (patients + controls) × run days,
  plus calibration and repeats: ______
Tests lost to expiration or opened stability: ______
Cost: (tests used + tests lost) × price per test,
  plus controls and calibrators bought separately: ______
Patient results: patient samples × run days: ______
Cost per reportable result: cost ÷ patient results: ______

Before you approve

Where Manoa fits

Manoa checks each quote’s pack, delivered price and terms before an order goes out, then places the order you approve on your account. Your lab director decides which reagents are validated, and your staff set the run schedule and controls behind each count. Our purchasing examples include a lab approving the price difference on a replacement quote.