Why Group Comparisons Need In-House Lab Diagnostic Mix

Case Snapshot

VizVet reviewed 17 practices in one veterinary management group composed of practices owned by several different owners for the trailing twelve months ending July 2026. Fifteen practices were included in the updated In-House Lab comparison. The reported ratios ranged from 5.5% to 58.3%, even though the group benchmark was 20.0%. That spread is too wide to interpret as purchasing performance alone.

The full cohort spread

Figure 1. Reported In-House Lab COGS for the 15 included practices, with the 20.0% benchmark and 22.4% pooled cohort result.

The benchmark, cohort, and median are all mathematically valid. None of them establishes why an individual practice is high or low. A practice can appear favorable because manual diagnostics add substantial revenue with little product cost. Another can remain high after mix is considered, pointing to analyzer pricing, utilization, reagent cost, or mapping.

Six Practices with PIMS Diagnostic Detail

Six practices had enough PIMS item detail to classify In-House Lab revenue by methodology. Manual diagnostics ranged from 3.2% to 76.3% of revenue. POCT ranged from 4.5% to 44.1%. Analyzer diagnostics ranged from 18.1% to 80.4%. The blended ratios therefore compared materially different services.

Figure 2. Revenue mix for the six practices with PIMS diagnostic detail. The label beside each practice shows its reported blended In-House Lab COGS.

Three comparisons change the interpretation

• Practice A is manual-heavy. Manual diagnostics were 76.3% of its In-House Lab revenue. Its 5.5% ratio therefore does not represent the same service mix as the other practices.

• Practices N and I are POCT-heavy. POCT represented 41.2% and 44.1% of their revenue, yet their blended ratios were 33.4% and 20.9%. Mix narrows the question but does not answer it.

• Practices O and J are analyzer-heavy. Analyzer revenue represented 76.5% and 80.4%, but blended COGS was 58.3% at Practice O and 22.1% at Practice J. Similar mix does not guarantee similar economics.

Interpretation guardrail: Diagnostic mix explains why some practices should not be compared at the blended-account level. It does not excuse every variance. Once two practices have similar mix, a large remaining difference becomes more actionable.

The Manual Diagnostic Denominator Effect

The review recalculated In-House Lab COGS after removing manual diagnostic revenue from the denominator while leaving recorded costs unchanged. This is an analytical sensitivity, not a replacement accounting ratio. It shows how much low-product-cost revenue influenced the blended result.

Figure 3. Reported blended COGS compared with the analytical sensitivity after removing Manual Diagnostic revenue from the denominator.

What the Adjustment Reveals

• Practice A's apparently exceptional 5.5% result becomes 23.1% after manual revenue is removed. Most of the apparent advantage came from service mix.

• The cohort rises only 2.4 points because manual diagnostics are unevenly concentrated. A cohort-level adjustment can hide a much larger practice-level effect.

• Practice O remains high at 60.2%. Its 3.2% manual share cannot explain the result, so pricing, utilization, reagent cost, analyzer commitments, inventory control, mapping, and data completeness warrant review.

• Practice M remains above the benchmark after adjustment. Manual revenue softened its reported percentage, but it did not create the whole variance.

What the Group Can and Cannot Conclude

No practice in the review booked complete In-House Lab costs by modality. Revenue mix can explain why the blended ratios differ, but it cannot confirm whether POCT kits or analyzer reagents are purchased, used, and priced effectively.

A Better Group Comparison Sequence

VizVet Management View

A group benchmark should start an investigation, not finish one. Blended In-House Lab COGS identifies outliers but combines three operating models. The supplemental structure allows a group to determine whether an apparent variance comes from diagnostic mix or persists within a comparable modality. That distinction improves purchasing, pricing, utilization, inventory, and equipment decisions.

Bottom line: The useful comparison is not simply 6301 divided by 5301. It is Manual versus Manual, POCT versus POCT, and Analyzer versus Analyzer, supported by consistent mappings and complete periods.

Data Basis and Analytical Limits

The case uses a COGS benchmark review from one veterinary management group composed of practices owned by several different owners for the trailing twelve months ending July 2026. Practices use publication labels that do not match the source aliases. The updated report included practices with one month of missing cost while retaining that month's revenue and called out those exceptions. Practice A's 5.5% result includes an August 2025 month without recorded 6301 cost, so it may be understated even before the manual-diagnostic sensitivity.

Manual, POCT, and Analyzer shares were inferred from PIMS item revenue. No reviewed practice booked complete In-House Lab cost by modality. The manual sensitivity removes revenue but leaves small manual consumable costs in COGS, so adjusted ratios are slightly overstated. Analyzer includes items not clearly identified as Manual or POCT in the source analysis.

External Reporting Remains Intact

The VizVet Supplemental In-House Lab revenue accounts 5311, 5312, and 5313 roll up to 5301 In-House Lab Revenue. The corresponding COGS accounts 6311, 6312, and 6313 roll up to 6301 In-House Lab COGS for Datalink and other external reporting.