NPI registry status
Active
2026 NPPES data Gastroenterology Physician NPI 1649294661 M.D.
Verify on CMS → Mark Chapman, M.D.
Gastroenterology Physician in New York, New York.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 16,601 in Gastroenterology Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
207
Medicare Part D claims · 44 beneficiaries · Gastroenterology Physician avg: 833
Compiled from official public sources by the PlainDoctor editorial team.
What the federal data shows
Mark Chapman, M.D. filed 207 Medicare Part D claims in 2023 as a Gastroenterology Physician in New York, New York.
- 207
- Part D claims, 2023
Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) - no proprietary rating or editorial opinion is applied.
Mark Chapman, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
207 49th percentile higher than 49% of 1,370,886 prescribers
Each bar is a band; taller bars hold more prescribers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source CMS Medicare Part D Prescriber Public Use File · 2023
◑
Board-eligible specialty (heuristic, not verified)
Mark Chapman, M.D. 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).
What does the federal data show about Mark Chapman, M.D.?
Quality data not reportedPrimary specialty
Gastroenterology Physician
Medicare Part D claims
207 75% vs specialty avg
Specialty distribution in New York
How Gastroenterology Physician compares to other specialties among New York providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Gastroenterology Physician. Verify directly:
How MIPS and board certification work
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).
Mark Chapman, M.D. appears in the CMS NPPES registry as a Gastroenterology Physician provider holding M.D. credentials at 12 E 86TH ST, New York, NY, 10028, with a listed phone of (212) 861-2000. NPI 1649294661 was issued on 07/26/2006.
Medicare Part D records for calendar year 2023 show 207 prescription claims written by this provider, covering 44 Medicare beneficiaries and totaling roughly $1.1 million in drug spend.
Gastroenterology Physician is a mid-sized specialty nationwide, with 16,601 enrolled providers across 54 states and an average of 833 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
Provider Details
| NPI | 1649294661 |
|---|---|
| Specialty | Gastroenterology Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 07/26/2006 |
License & disciplinary context - New York NYSBPMC 2023 annual report
Aggregate state board data only, NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across all ~100K New York medical licensees in 2023 - they are NOT specific to Mark Chapman, M.D.. To verify Mark Chapman, M.D.'s current license status, search the NYSBPMC public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.
312
Total board actions, New York 2023
Across 302 cases
3.12
Actions per 1,000 licensees
New York statewide rate
probation
Most common action type
89 cases
NYSBPMC publishes annual disciplinary statistics as part of public-record reporting under each state's Administrative Procedure Act. See the full breakdown by action type and year on the New York disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
207
Total Claims
$1.1M
Total Drug Cost
44
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 329
- Total Day Supply
- 9,455
- Generic Drug Cost
- $30K
- Antibiotic Claims
- 11
Patient Demographics
- Average Patient Age
- 73.7 years
- Avg HCC Risk Score
- 1.50
- Gender Split
- 68% female / 32% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Mark Chapman, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Stelara
Stelara
33 claims
- Mesalamine
Mesalamine
18 claims
- Mercaptopurine
Mercaptopurine
14 claims
- Omeprazole 13
Omeprazole
13 claims
- Humira(Cf) Pen 12
Humira(Cf) Pen
12 claims
- Linzess 11
Linzess
11 claims
| Drug | Claims |
|---|---|
| Stelara Ustekinumab | 33 |
| Mesalamine | 18 |
| Mercaptopurine | 14 |
| Omeprazole | 13 |
| Humira(Cf) Pen Adalimumab | 12 |
| Linzess Linaclotide | 11 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Gastroenterology Physician Overview
How Mark Chapman, M.D. fits within the Gastroenterology Physician landscape nationally.
16,601
Gastroenterology Physician Providers in US
54
States with Gastroenterology Physician
833
Avg Claims per Provider
Mark Chapman, M.D.'s 207 claims are below the specialty average of 833.
Nearby Gastroenterology Physician Providers in New York
Other clinicians with the same primary specialty enrolled in New York, drawn from the same CMS NPPES roster as Chapman.
Dr. Elie Abadie
MD
Brooklyn, NY
Dr. Hafsa Abbas
MD
Flushing, NY
Dr. Naeem Abbas
MD
Valley Stream, NY
Dr. Uzma Abbasi
M.D.
Oneida, NY
Amro Abdellatief
New York, NY
Compare Gastroenterology Physician nationally: see state-by-state distribution →
Before you book an appointment
Use this federal record as your verification checklist, not as a recommendation.
- Confirm the NPI record is current in the official CMS registry, providers update their own NPPES details, and moves can lag. Verify this NPI
- Check the active license and any disciplinary history with the New York medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Gastroenterology Physician peer on Medicare volume and prescribing patterns. Compare providers
Medicare Part D and MIPS figures describe practice patterns in federal programs only, they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.
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Frequently Asked Questions
What is Mark Chapman, M.D.'s specialty? ▼
Mark Chapman, M.D. specializes in Gastroenterology Physician and practices in New York, New York. Credentials: M.D..
How much does Mark Chapman, M.D. prescribe under Medicare Part D? ▼
In 2023, Mark Chapman, M.D. wrote 207 Medicare Part D claims totaling $1.1M in drug costs for 44 beneficiaries.
Where is Mark Chapman, M.D. located? ▼
Mark Chapman, M.D. is located at 12 E 86TH ST, New York, NY, 10028. Phone: (212) 861-2000.
What is Mark Chapman, M.D.'s NPI number? ▼
Mark Chapman, M.D.'s National Provider Identifier (NPI) is 1649294661, issued on 07/26/2006.
How many Gastroenterology Physician providers are there in the US? ▼
There are 16,601 Gastroenterology Physician providers across 54 states in the US. The average Gastroenterology Physician provider writes 833 Medicare Part D claims per year.
What drugs does Mark Chapman, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Mark Chapman, M.D.'s most frequently prescribed drugs include Stelara, Mesalamine, Mercaptopurine. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Mark Chapman, M.D. accept Medicare? ▼
Mark Chapman, M.D. appears in CMS Medicare data with 207 Part D claims and 44 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Mark Chapman, M.D.'s credentials? ▼
Mark Chapman, M.D.'s NPI is 1649294661 with credentials M.D.. 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
View source datasets and methodology notes
- 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
Compiled from official public sources by the PlainDoctor editorial team.
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.