Other Ambulatory Health Care Services (U.S.) — Rollup Primer

NAICS 2022 code 6219. A Histometrics primer for public- and private-market investors.

NAICS = North American Industry Classification System, the U.S. government's standard for grouping businesses by their primary activity. This is a NAICS industry group (4-digit) — one level below the subsector 621 (Ambulatory Health Care Services) and one level above the two 5-digit industries it contains. "Ambulatory" simply means care delivered without an overnight hospital admission.

1. Overview

6219 is the leftover drawer of outpatient medicine. Within ambulatory (walk-in / same-day) care, the government already files physician offices under 6211, dentists under 6212, other practitioners under 6213, outpatient centers under 6214, medical and diagnostic labs under 6215, and home health under 6216. Every ambulatory activity that fits none of those named codes lands in 6219 — Other Ambulatory Health Care Services.

What lands there is genuinely miscellaneous. The group holds exactly two members, and they have almost nothing in common:

• 62191 — Ambulance Services. Emergency (911) and non-emergency medical transport, by ground and by air, with treatment delivered en route. An essential, recession-resistant transport-and-treatment business with hard economics.
• 62199 — All Other Ambulatory Health Care Services. Itself a residual bucket, splitting into blood and organ banks (621991 — a few large, capital-heavy, heavily regulated operators) and a long tail of miscellaneous outpatient services (621999 — drug testing, health screening, remote cardiac monitoring, case management, and a dozen other small niches).

For an investor the honest headline is that 6219 is not a market you can buy — it is a classification bracket. Its two children run on unrelated economic engines, answer to unrelated regulators, respond to unrelated demand curves, and are held by unrelated — and mostly non-investable — owners. Pooling them creates no single margin profile, no shared unit of output, and no obvious public vehicle. The distinctive value of a rollup view is therefore the contrast: which side is bigger, which is growing, who owns each, and how (if at all) an outside investor can get exposure.

Reported federal receipts for the whole group were about $65.6 billion (2022) [1]. As Section 3 explains, that figure materially understates the real economic system on both sides.

2. What's inside — the two children and how they differ

The lead table below is the point of this page: the two members side by side. All share and per-unit figures are computed from our ground-truth federal statistics for the group and its children [1][2][5][6][7][8].

EMS = emergency medical services. Now the same split in numbers:

CR4 = combined revenue share of the four largest firms; HHI = Herfindahl-Hirschman Index (sum of squared market shares — lower means less concentrated).

The one-line contrast. By dollars, 62199 is more than twice the size of 62191 (~69% vs. ~31% of group receipts). But by employment the two are close (~54% vs. ~46%) — a sign that ambulance work is more labor-intensive per dollar of revenue (crews standing ready 24/7), while much of 62199's revenue flows through capital-heavy plasma and organ operations. Both children are dominated by owners you cannot buy on a stock exchange, but for opposite reasons: 62191 because the plurality of the activity is tax-funded municipal and fire-based EMS; 62199 because its high-value core is either nonprofit (blood/organ) or a scatter of sole-proprietor shops.

Why they are filed together (and why that's misleading). NAICS is a residual hierarchy: once every named ambulatory activity is assigned, ambulance transport and "everything else ambulatory" fall into the leftover 4-digit group. That is an accounting convenience, not a market. The rest of this primer treats the two children as distinct opportunity sets under one label.

3. How big it is

Our ground-truth federal figures for NAICS 6219 combine the 2022 Economic Census (receipts, firms, concentration) with 2023 County Business Patterns (CBP: establishments, employment, payroll). The two survey programs cover different years, so the blocks are not a single snapshot [1][2].

That works out to average pay of roughly $58,700 per worker and average receipts of about $6.2 million per firm — small-business economics on average, but stretched across two very different shapes. (For reference, the children run ~$52,000/worker on the ambulance side and ~$65,000/worker on the miscellaneous side [6][8].)

Reading the concentration. The group HHI of 143.3 is lower than either child's (62199 is 161.4; 62191's own HHI is suppressed in the federal data, but its CR4 of 35.4% is nearly double the group's 19.3%, so it is plainly the more concentrated of the two). Combining two industries whose leaders don't overlap dilutes every firm's share, so the group looks more fragmented than either part — which is just another way of saying no single company is large across "6219" as a whole. U.S. antitrust agencies treat a market above 1,800 HHI as "highly concentrated" [9]; at 143.3 this group sits more than an order of magnitude below that line. The 10,627 firms are essentially the two children added together (3,002 + 7,638), a handful of multi-site ambulance and plasma operators over a very long tail of single-site shops.

Undercount and scope caveats — read before quoting the $65.6 billion. The two children are undercounted in large but opposite ways:

1. Government EMS is missing (62191 side). The Census counts private employer businesses and generally excludes government-owned establishments, so tax-funded municipal, fire-department, and volunteer EMS — the plurality of U.S. 911 response — never appears in these receipts [3]. Treat the ambulance portion as the private, for-profit footprint only.
2. The profit lives next door, and the small operators fall out of frame (62199 side). The high-value step — turning collected plasma into immunoglobulin and other medicines — is booked as pharmaceutical manufacturing (NAICS 325414), not here; nonprofit blood centers and organ procurement organizations price on cost recovery, not margin; and the employer-business frame excludes sole proprietors without payroll, so much of the miscellaneous long tail is undercounted [4].
3. No fine-grained federal splits or growth series at this level. Our ground-truth data give no ambulance-vs-blood-vs-miscellaneous margin, pricing, or growth breakout, and no official growth rate for 6219 — the "direction of travel" above is qualitative, drawn from the child primers. Where a value is suppressed we do not state one.

Treat ~$65.6 billion as a floor for the collection-and-services layer, with the true economic system — plasma medicines especially, plus the whole government-EMS system — materially larger once adjacent activity is added.

4. The investable universe — where value concentrates across the children

There is no exchange-traded fund (ETF) and no clean public proxy for NAICS 6219, and none for either child. Value concentrates in very different, and mostly indirect, places on each side. Figures below are recent reported scale, not recommendations; tickers are reserved for this and the how-to-invest section.

Side 62191 — Ambulance: a thin but newly opened public window over a mostly private base. Public markets were essentially closed to this industry until Global Medical Response (NYSE: GMRS) — the largest U.S. EMS provider, parent of American Medical Response — listed in May 2026, creating the first near-pure-play option [3]. Adjacent public exposure runs through DocGo (Nasdaq: DCGO), a technology-enabled mobile-health firm, and ModivCare (Nasdaq: MODV), which coordinates non-emergency medical transportation rather than operating ambulances. The bulk of the industry is private or public-sector: air-medical leader Air Methods (lender-owned after a 2023 restructuring), the employee-owned Acadian Ambulance, Denmark's Falck, private-equity roll-ups such as Priority Ambulance, and — the largest single share of 911 response — municipal, fire-based, and volunteer EMS, which is not investable [3].

Side 62199 — All Other: value sits up-/downstream (blood/organ) or scattered across niches and diversified parents (miscellaneous). On the blood/organ side, the banks themselves are largely nonprofit and unbuyable, so ownable value is adjacent — plasma and plasma-medicine makers (CSL, Grifols, Takeda, ADMA Biologics), collection equipment (Haemonetics), and organ-preservation technology (TransMedics, XVIVO) [4]. On the miscellaneous side, value sits inside the code but scattered — focused names such as iRhythm (remote cardiac monitoring), CorVel (case management), and Concentra (occupational health), plus small segments of diagnostics, device, and managed-care majors — with most of the industry held privately by PE roll-ups [4].

The synthesis. Across the whole group, you are always buying a slice, never "the industry": a single leveraged operator (ambulance), a biologics manufacturer whose collection centers happen to fall in the code (plasma), or a niche med-tech or services roll-up (miscellaneous). No instrument gives you 6219 as a whole, and none should — the parts don't move together.

5. How the money works

The group runs on at least three unrelated economic engines; there is no common unit of output for 6219.

• Ambulance (62191) — a cost-of-readiness transport business. Owners earn the spread between what they collect per transport and the cost of standing ready to respond around the clock. Revenue = transports × net collections per transport, billed by level of service plus loaded mileage; the key operating metric is unit-hour utilization (transports per staffed ambulance-hour). Payer mix is destiny: government payers (Medicare, Medicaid) are the volume majority and reimburse below cost, cross-subsidized by commercial insurance, self-pay, and municipal subsidies [3].
• Blood and organ banks (621991, inside 62199) — feedstock and cost-recovery. Nonprofit blood centers charge hospitals a per-unit cost-recovery fee on sticky multi-year contracts; for-profit source-plasma networks pay donors and sell plasma as a raw-material feedstock into high-margin medicines; organ procurement organizations are cost-reimbursed regional monopolies measured in organs recovered, not dollars [4].
• Miscellaneous services (621999, inside 62199) — transactional service fees. Revenue is fundamentally volume × price per test, screening, monitoring study, or case, paid by employers, payers/Medicare (via reimbursement codes), per-member-per-month contracts, or consumers. The main cost is clinical labor; the interpretation/software layer can be high-margin [4].

The one economic sentence that spans the group: almost everything here is priced by someone other than a walk-in customer — a government fee schedule, a hospital contract, an employer, or a downstream drug maker — so revenue quality turns on payer mix and contract terms, not on retail demand.

6. What drives demand

• Aging population and chronic disease are the one genuine common thread, lifting both children — more 911 calls and interfacility transfers on the ambulance side, and more transfusion candidates, arrhythmia detection, screening, and coordinated care on the 62199 side. The U.S. 65-and-older population reached 61.2 million (18.0%) in 2024 [10].
• Ambulance-specific: a large, economically insensitive baseline of accidents and acute events, plus growth in scheduled interfacility and dialysis transport as hospital networks centralize specialty care [3].
• Blood/organ-specific: immunoglobulin (IG) demand is the single biggest growth driver anywhere in the group, pulling plasma volumes higher; blood demand is essential but flat-to-soft; organ demand vastly exceeds supply, with preservation technology expanding usable volumes [4].
• Miscellaneous-specific: hiring levels and regulatory mandates (e.g., transportation drug testing) set testing volume, while cannabis liberalization is a genuine headwind to pre-employment marijuana screening [4].

Demand is broadly defensive on both sides, but stable demand does not guarantee stable margins — those are set by reimbursement and payer mix, not volume.

7. Regulation

Regulation here is set by the activity, not the shared code, and the two children face almost entirely separate regimes:

• Ambulance (62191): the Medicare Ambulance Fee Schedule (CMS) is the reference every payer negotiates around, with rural/urban add-ons that Congress must periodically renew; the No Surprises Act bans balance billing for air ambulances but explicitly excludes ground ambulances; and state licensing plus exclusive service areas control who may run 911 in a jurisdiction [3].
• Blood and organ banks (621991): the FDA's Center for Biologics Evaluation and Research regulates blood and plasma (a biologics license is required for source-plasma operators), while organs are regulated separately by HRSA's Organ Procurement and Transplantation Network, and selling organs is a federal crime under the National Organ Transplant Act [4].
• Miscellaneous services (621999): workplace drug testing follows SAMHSA/DOT rules, lab steps fall under CLIA, cardiac monitors need FDA clearance, reimbursement is governed by CMS coding, and billing exposure runs through the Anti-Kickback Statute, False Claims Act, and Stark law [4].

The common denominator is that all of it is high-compliance — but an investor must underwrite the specific regime, because a fact learned on one side (biologics licensure, ambulance fee schedules, workplace-testing rules) rarely transfers to the other.

8. Competitive dynamics and consolidation

Both children are consolidating, for different reasons and by different mechanisms.

• Ambulance (62191): fragmented with a consolidating top — the largest four private firms hold ~35% of revenue [5] over a long tail, and competition is for contracts (municipal 911 franchises, hospital and nursing-home transport), not for walk-in customers. Private equity has been the consolidator for a decade (GMR itself is a KKR construction), while tax-funded fire and municipal EMS cap any one firm's national reach [3].
• All Other (62199): two consolidation stories under one roof — plasma is a global oligopoly (CSL, Grifols, Takeda, Octapharma) competing on center footprint and manufacturing scale, nonprofit blood centers merge to survive declining volume against high fixed costs, and the miscellaneous long tail is a roll-up playground where PE consolidates occupational health, drug-testing administration, case management, and screening [4].

At the group level the arithmetic of consolidation is muted: the largest four firms take only 19.3% of 6219 revenue [1], because the biggest ambulance operators and the biggest blood/plasma and services firms are entirely different companies. Federal agencies (FTC, DOJ, HHS) have specifically scrutinized healthcare roll-ups and private-equity ownership, so the consolidation thesis carries policy risk on both sides [4].

9. Risks

Shared across the group:

• Reimbursement and pricing pressure — government payers and hospital/employer contracts set most prices, and cuts flow straight to margin.
• Labor — chronic shortages of EMTs and paramedics (ambulance) and of technicians, nurses, and care managers (62199), on the largest cost line.
• High compliance and enforcement exposure — biologics, EMS licensure, workplace-testing, and billing/coding rules, with live False Claims Act risk on the services side.
• "Residual-bucket" measurement risk — because 6219 (and 62199 within it) is a catch-all whose activity spills into pharmaceutical manufacturing, labs, physician offices, hospitals, and government budgets, it is hard to size or benchmark as an investment theme.
• Public-company mismatch — a listed name can look like ambulance, blood/organ, or ambulatory-services exposure while most of its earnings come from unrelated pharmaceuticals, devices, or managed care. Separate the relevant segment before valuing it.

Concentrated on 62191: below-cost government reimbursement; policy cliffs (Medicare add-ons need re-legislating); ground-ambulance surprise-billing reform that could cap cross-subsidizing commercial charges; and heavy private-equity leverage [3].

Concentrated on 62199: chronic blood-donor shortages and structural transfusion-volume decline against fixed costs; IG demand/pricing cycles and company leverage; the multi-year federal overhaul of the organ-transplant system; reimbursement cuts for monitoring names; cannabis-driven erosion of drug testing; and debt-funded roll-up integration risk [4].

10. How to invest, and the outlook

Public routes are thin and side-specific. For the ambulance side, Global Medical Response (NYSE: GMRS) is the only large near-pure-play — but understand it as a leveraged, thin-margin, KKR-controlled market leader — with DocGo (Nasdaq: DCGO) and ModivCare (Nasdaq: MODV) as adjacent exposure [3]. For the 62199 side, exposure is indirect: plasma and plasma-medicine makers (CSL, Grifols, Takeda, ADMA), collection equipment (Haemonetics), and organ-preservation tech (TransMedics, XVIVO) on the blood/organ side; focused names such as iRhythm (remote cardiac monitoring), CorVel (case management), and Concentra (occupational health) on the miscellaneous side [4]. There is no ETF at the group or child level, and no instrument that buys "6219."

Private routes hold most of the group. On the ambulance side the private market is the industry — PE healthcare-services funds, direct ownership or roll-up of regional operators, and municipal-contract operators. On the 62199 side the accessible private assets are for-profit plasma collection networks and cord-blood storage (blood/organ), and PE buy-and-build in occupational health, drug-testing administration, case management, and screening (miscellaneous). Diligence differs by segment: contract duration, transport volume, payer mix, staffing, and leverage (ambulance); licensing, donor supply, referral/coding practices, denial rates, and integration track record (62199).

Outlook (editorial judgment). 6219 is a doubly residual bracket — a leftover industry group whose larger member is itself a leftover bucket — and it should be read as such. The commercially favored trajectories are, on the ambulance side, a defensive top line supported by aging demographics but constrained by policy and payer mix; and on the 62199 side, vertically integrated plasma and organ-preservation technology plus recurring-contract care management and occupational health, against a flat-to-declining nonprofit blood core and soft drug testing. The single lesson the concentration data teach — group CR4 of 19.3% and HHI of 143.3, both below either child — is that no company is large across "6219" as a whole. This is a set of niches to mine one at a time, on the correct side, not a market to buy wholesale.

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Sources

1. U.S. Census Bureau, 2022 Economic Census — Concentration of Largest Firms, NAICS 6219 (group receipts ~$65.619B; firms 10,627; CR4 19.3%, CR8 28.1%, CR20 39.8%, CR50 50.2%; HHI 143.3). Histometrics ground-truth federal statistics for this level. https://data.census.gov/table/ECNSIZE2022.EC2200SIZECONCEN
2. U.S. Census Bureau, County Business Patterns 2023 — NAICS 6219 (establishments 17,193; employees 387,030; annual payroll ~$22.716B; Q1 payroll ~$5.644B). Histometrics ground-truth federal statistics for this level. https://www.census.gov/programs-surveys/cbp.html
3. Histometrics primer for NAICS 62191 — Ambulance Services (this group's transport child), which carries the full sourcing: CMS/MedPAC on the Ambulance Fee Schedule and add-ons; the No Surprises Act ground-ambulance exclusion; EMS ownership-mix and payer/reimbursement data; and Reuters/GMR/KKR on the 2026 NYSE IPO. See that primer's numbered Sources list.
4. Histometrics primer for NAICS 62199 — All Other Ambulatory Health Care Services (this group's residual child), which carries the full sourcing for blood/plasma (CSL, Grifols, Takeda, ADMA, Haemonetics), organ procurement and preservation (TransMedics, XVIVO, HRSA/OPTN, NOTA), and the miscellaneous niches (iRhythm, CorVel, Concentra; SAMHSA/DOT, CMS/CPT, FCA enforcement). See that primer's numbered Sources list.
5. U.S. Census Bureau, 2022 Economic Census — Concentration of Largest Firms, NAICS 62191 (receipts ~$20.3B; firms 3,002; CR4 35.4%; HHI suppressed). https://data.census.gov/table/ECNSIZE2022.EC2200SIZECONCEN
6. U.S. Census Bureau, County Business Patterns 2023 — NAICS 62191 (5,556 establishments; 179,939 employees; ~$9.31B annual payroll). https://www.census.gov/programs-surveys/cbp.html
7. U.S. Census Bureau, 2022 Economic Census — Concentration of Largest Firms, NAICS 62199 (receipts ~$45.296B; firms 7,638; CR4 20.5%; HHI 161.4). https://data.census.gov/table/ECNSIZE2022.EC2200SIZECONCEN
8. U.S. Census Bureau, County Business Patterns 2023 — NAICS 62199 (11,637 establishments; 207,091 employees; ~$13.407B annual payroll). https://www.census.gov/programs-surveys/cbp.html
9. U.S. Department of Justice & Federal Trade Commission, 2023 Merger Guidelines, Guideline 1 (HHI thresholds), 2023. https://www.justice.gov/atr/merger-guidelines/applying-merger-guidelines/guideline-1
10. U.S. Census Bureau, "Older Adults Outnumber Children..." (2025) — 65+ population 61.2M / 18.0% (2024). https://www.census.gov/newsroom/press-releases/2025/older-adults-outnumber-children.html