NPI registry status
Active
2026 NPPES data Geriatric Psychiatry Physician NPI 1518987478 M.D.
Verify on CMS → William Clark, M.D.
Geriatric Psychiatry Physician in Laurel, Mississippi.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 785 in Geriatric Psychiatry 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
410
Medicare Part D claims · 47 beneficiaries · Geriatric Psychiatry Physician avg: 2K
Generic prescribing
94%
generic claims · 6% brand-name · higher generic rates reduce patient out-of-pocket costs
Source: CMS Medicare Part D Prescriber Public Use File, 2023
Compiled from official public sources by the PlainDoctor editorial team.
What the federal data shows
William Clark, M.D. filed 410 Medicare Part D claims in 2023 as a Geriatric Psychiatry Physician in Laurel, Mississippi, prescribing 94% generic.
- 410
- Part D claims, 2023
- 94%
- generic prescribing
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.
William Clark, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
410 Top 38% higher than 62% 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)
William Clark, 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 William Clark, M.D.?
Quality data not reportedPrimary specialty
Geriatric Psychiatry Physician
Medicare Part D claims
410 74% vs specialty avg
Specialty distribution in Mississippi
How Geriatric Psychiatry Physician compares to other specialties among Mississippi 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 Geriatric Psychiatry 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).
William Clark, M.D. appears in the CMS NPPES registry as a Geriatric Psychiatry Physician provider holding M.D. credentials at 1603 OLD AMY RD, Laurel, MS, 39440, with a listed phone of (601) 428-7100. NPI 1518987478 was issued on 07/20/2006.
Medicare Part D records for calendar year 2023 show 410 prescription claims written by this provider, covering 47 Medicare beneficiaries and totaling roughly $29K in drug spend, split 6% brand-name and 94% generic by claim count.
Geriatric Psychiatry Physician is a narrow specialty nationwide, with 785 enrolled providers across 46 states and an average of 1,586 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 | 1518987478 |
|---|---|
| Specialty | Geriatric Psychiatry Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 07/20/2006 |
Brand vs generic prescribing mix · Generic-heavy
William Clark, M.D. - brand share 6.0%
Geriatric Psychiatry Physician average
6% brand-name claims vs 94% generic, on 410 2023 Medicare Part D claims.
The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
410
Total Claims
$29K
Total Drug Cost
47
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 481
- Total Day Supply
- 14,142
- Brand vs Generic
- 6% brand / 94% generic
- Brand Drug Cost
- $11K
- Generic Drug Cost
- $18K
Patient Demographics
- Average Patient Age
- 72.9 years
- Avg HCC Risk Score
- 1.77
- Gender Split
- 53% female / 47% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What William Clark, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Buprenorphine-Nalo…
Buprenorphine-Naloxone
68 claims
- Quetiapine Fumarate
Quetiapine Fumarate
44 claims
- Duloxetine Hcl
Duloxetine Hcl
42 claims
- Trazodone Hcl
Trazodone Hcl
32 claims
- Mirtazapine 22
Mirtazapine
22 claims
- Clonazepam 18
Clonazepam
18 claims
- Risperidone 17
Risperidone
17 claims
- Bupropion Hcl Sr 16
Bupropion Hcl Sr
16 claims
| Drug | Claims |
|---|---|
| Buprenorphine-Naloxone Buprenorphine Hcl/Naloxone Hcl | 68 |
| Quetiapine Fumarate | 44 |
| Duloxetine Hcl | 42 |
| Trazodone Hcl | 32 |
| Mirtazapine | 22 |
| Clonazepam | 18 |
| Risperidone | 17 |
| Bupropion Hcl Sr Bupropion Hcl | 16 |
| Venlafaxine Hcl Er Venlafaxine Hcl | 15 |
| Bupropion Hcl | 14 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Geriatric Psychiatry Physician Overview
How William Clark, M.D. fits within the Geriatric Psychiatry Physician landscape nationally.
785
Geriatric Psychiatry Physician Providers in US
46
States with Geriatric Psychiatry Physician
1,586
Avg Claims per Provider
William Clark, M.D.'s 410 claims are below the specialty average of 1,586.
Nearby Geriatric Psychiatry Physician Providers in Mississippi
Other clinicians with the same primary specialty enrolled in Mississippi, drawn from the same CMS NPPES roster as Clark.
Compare Geriatric Psychiatry 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 Mississippi medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Geriatric Psychiatry 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 William Clark, M.D.'s specialty? ▼
William Clark, M.D. specializes in Geriatric Psychiatry Physician and practices in Laurel, Mississippi. Credentials: M.D..
How much does William Clark, M.D. prescribe under Medicare Part D? ▼
In 2023, William Clark, M.D. wrote 410 Medicare Part D claims totaling $29K in drug costs for 47 beneficiaries.
Where is William Clark, M.D. located? ▼
William Clark, M.D. is located at 1603 OLD AMY RD, Laurel, MS, 39440. Phone: (601) 428-7100.
What is William Clark, M.D.'s NPI number? ▼
William Clark, M.D.'s National Provider Identifier (NPI) is 1518987478, issued on 07/20/2006.
Does William Clark, M.D. prescribe more brand-name or generic drugs? ▼
William Clark, M.D.'s prescribing is 6% brand-name and 94% generic drugs by claim count, with $11K in brand drug costs.
How many Geriatric Psychiatry Physician providers are there in the US? ▼
There are 785 Geriatric Psychiatry Physician providers across 46 states in the US. The average Geriatric Psychiatry Physician provider writes 1,586 Medicare Part D claims per year.
What drugs does William Clark, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, William Clark, M.D.'s most frequently prescribed drugs include Buprenorphine-Naloxone, Quetiapine Fumarate, Duloxetine Hcl. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does William Clark, M.D. accept Medicare? ▼
William Clark, M.D. appears in CMS Medicare data with 410 Part D claims and 47 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify William Clark, M.D.'s credentials? ▼
William Clark, M.D.'s NPI is 1518987478 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.