2026 NPPES data Geriatric Medicine (Internal Medicine) Physician NPI 1639178445 D.O.
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GRANT BARNUM, D.O.

Geriatric Medicine (Internal Medicine) Physician in LAKE OZARK, Missouri. CMS National Plan and Provider Enumeration System profile including specialty classification, practice address, and Medicare prescribing data when reported.

Federal data — no proprietary rating. PlainDoctor publishes the actual CMS NPPES and Medicare records — NPI registration, specialty, practice location, and prescribing data — without a composite score or editorial opinion on top. Every field traces to a federal source.
Prescribing volume
187
Medicare Part D claims · 30 beneficiaries · Geriatric Medicine (Internal Medicine) Physician avg: 4K
What the federal data reveals: GRANT BARNUM, D.O. is a Geriatric Medicine (Internal Medicine) Physician ([object Object]) practicing in LAKE OZARK, Missouri with a Medicare Part D prescribing footprint of 187 claims across 30 beneficiaries .

What stands out: GRANT BARNUM, D.O. filed 187 Medicare Part D claims in 2023 across LAKE OZARK, Missouri. Every figure on this page comes straight from federal CMS records, with no proprietary rating applied.

Board-eligible specialty (heuristic — not verified)

GRANT BARNUM, D.O. practices in an ABMS-board-eligible specialty but we don't have enough CMS-participation signals to confirm active board-certified status. Consult CertificationMatters.org (the official ABMS public lookup).

GRANT BARNUM, D.O. at a glance

Quality data not reported

NPI registry status

Active

Issued 07/14/2005

NPI 1639178445

Primary specialty

Geriatric Medicine (Internal Medicine) Physician

Niche

4,161 US NPIs in this specialty

Medicare Part D claims

187 96% vs specialty avg

2023 prescription claims

Specialty avg: 4,450

Specialty distribution in Missouri

How Geriatric Medicine (Internal Medicine) Physician compares to other specialties among Missouri providers

Missouri providers

Geriatric Medicine (Internal Medicine) Physician share within Missouri

1. Geriatric Medicine (Internal Medicine) Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Geriatric Medicine (Internal Medicine) Physician share within Missouri

Specialty board-certification context

Estimated specialty board-certified rate — Geriatric Medicine (Internal Medicine) Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Geriatric Medicine (Internal Medicine) Physician ABMS/AOA estimate

Est. board-certified rate (Geriatric Medicine (Internal Medicine) Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Geriatric Medicine (Internal Medicine) Physician) — ABMS / AOA estimate

The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.

Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).

GRANT BARNUM, D.O. is a Geriatric Medicine (Internal Medicine) Physician provider practicing in LAKE OZARK, Missouri, according to the CMS National Plan and Provider Enumeration System (NPPES). Credentials: D.O.. NPI: 1639178445. This profile includes practice location, specialty classification, and organizational affiliations from the CMS provider registry. Provider information is self-reported to CMS and updated monthly.

GRANT BARNUM, D.O. appears in the CMS NPPES registry as a Geriatric Medicine (Internal Medicine) Physician provider holding D.O. credentials at 1870 BAGNELL DAM BLVD, LAKE OZARK, MO, 65049, with a listed phone of (573) 365-2318. NPI 1639178445 was issued on 07/14/2005. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what BARNUM most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 187 prescription claims written by this provider, covering 30 Medicare beneficiaries and totaling roughly $3K in drug spend. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy.

Geriatric Medicine (Internal Medicine) Physician is a narrow specialty nationwide, with 4,161 enrolled providers across 52 states and an average of 4,450 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.

Practice Address

1870 BAGNELL DAM BLVD
LAKE OZARK, MO 65049

Provider Details

NPI 1639178445
Specialty Geriatric Medicine (Internal Medicine) Physician
Credentials D.O.
Gender Male
NPI Issued 07/14/2005

Medicare Part D Prescribing Data

CMS Medicare Part D prescriber-level data for calendar year 2023.

187
Total Claims
$3K
Total Drug Cost
30
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
296
Total Day Supply
8,468
Generic Drug Cost
$2K

Patient Demographics

Average Patient Age
78.4 years
Avg HCC Risk Score
1.36
Gender Split
60% female / 40% male

Top Prescribed Drugs (Medicare Part D)

Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.

Drug Claims
Risperidone
28
Atorvastatin Calcium
25
Gabapentin
15
Omega-3 Acid Ethyl Esters
14
Omeprazole
14
Tamsulosin Hcl
14

* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.

Geriatric Medicine (Internal Medicine) Physician Overview

How GRANT BARNUM, D.O. fits within the Geriatric Medicine (Internal Medicine) Physician landscape nationally.

4,161
Geriatric Medicine (Internal Medicine) Physician Providers in US
52
States with Geriatric Medicine (Internal Medicine) Physician
4,450
Avg Claims per Provider

GRANT BARNUM, D.O.'s 187 claims are below the specialty average of 4,450.

Nearby Geriatric Medicine (Internal Medicine) Physician Providers in Missouri

Other clinicians with the same primary specialty enrolled in Missouri, drawn from the same CMS NPPES roster as BARNUM.

Compare Geriatric Medicine (Internal Medicine) Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is GRANT BARNUM, D.O.'s specialty?
GRANT BARNUM, D.O. specializes in Geriatric Medicine (Internal Medicine) Physician and practices in LAKE OZARK, Missouri. Credentials: D.O..
How much does GRANT BARNUM, D.O. prescribe under Medicare Part D?
In 2023, GRANT BARNUM, D.O. wrote 187 Medicare Part D claims totaling $3K in drug costs for 30 beneficiaries.
Where is GRANT BARNUM, D.O. located?
GRANT BARNUM, D.O. is located at 1870 BAGNELL DAM BLVD, LAKE OZARK, MO, 65049. Phone: (573) 365-2318.
What is GRANT BARNUM, D.O.'s NPI number?
GRANT BARNUM, D.O.'s National Provider Identifier (NPI) is 1639178445, issued on 07/14/2005.
How many Geriatric Medicine (Internal Medicine) Physician providers are there in the US?
There are 4,161 Geriatric Medicine (Internal Medicine) Physician providers across 52 states in the US. The average Geriatric Medicine (Internal Medicine) Physician provider writes 4,450 Medicare Part D claims per year.
What drugs does GRANT BARNUM, D.O. prescribe most often?
Based on 2023 Medicare Part D data, GRANT BARNUM, D.O.'s most frequently prescribed drugs include Risperidone, Atorvastatin Calcium, Gabapentin. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does GRANT BARNUM, D.O. accept Medicare?
GRANT BARNUM, D.O. appears in CMS Medicare data with 187 Part D claims and 30 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify GRANT BARNUM, D.O.'s credentials?
GRANT BARNUM, D.O.'s NPI is 1639178445 with credentials D.O.. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.

Data Sources

Provider Directory
CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
Specialty Classification
NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
Prescribing Data
CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
Limitations
Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.

See our complete data methodology for details on how we collect and process government data.

Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).

Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology