NPI registry status
Active
2026 NPPES data Specialist NPI 1598769358 MD
Verify on CMS → Ann Mass, MD
Specialist in Aspen, Colorado.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 69,608 in Specialist, 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
3K
Medicare Part D claims · 316 beneficiaries · Specialist avg: 1K
Generic prescribing
84%
generic claims · 15% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$15.33
1 payments · CMS Open Payments (Sunshine Act)
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
Ann Mass, MD filed 3,086 Medicare Part D claims in 2023 as a Specialist in Aspen, Colorado, prescribing 84% generic.
- 3K
- Part D claims, 2023
- 84%
- generic prescribing
- $15.33
- industry payments (Sunshine Act)
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.
Ann Mass, MD's Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
3,086 Top 11% higher than 89% 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
What does the federal data show about Ann Mass, MD?
Quality data not reportedPrimary specialty
Specialist
Medicare Part D claims
3,086 109% vs specialty avg
Specialty distribution in Colorado
How Specialist compares to other specialties among Colorado 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 Specialist. 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).
Ann Mass, MD appears in the CMS NPPES registry as a Specialist provider holding MD credentials at 225 N MILL ST, Aspen, CO, 81611, with a listed phone of (970) 544-1234. NPI 1598769358 was issued on 06/09/2005.
Medicare Part D records for calendar year 2023 show 3,086 prescription claims written by this provider, covering 316 Medicare beneficiaries and totaling roughly $466K in drug spend, split 15% brand-name and 84% generic by claim count, with an opioid prescribing rate of 0.5%.
Specialist is a high-volume specialty nationwide, with 69,608 enrolled providers across 55 states and an average of 1,474 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 | 1598769358 |
|---|---|
| Specialty | Specialist |
| Credentials | MD |
| Gender | Female |
| NPI Issued | 06/09/2005 |
Industry payments received (2024) - CMS Open Payments transparency data
The federal Physician Payments Sunshine Act (part of the Affordable Care Act) requires drug and medical-device manufacturers + group purchasing organizations to publicly report payments and other transfers of value to physicians and teaching hospitals. The data below covers 2024 for Ann Mass, MD. Source: openpaymentsdata.cms.gov.
Total received
$15
Largest payer
Amgen Inc.
Most common payment type
Food and Beverage
Industry payments are not necessarily indicators of bias, they include research funding, consulting fees for evidence-based work, royalties for inventions, food at conferences, and similar items. The disclosure exists for transparency. Read our methodology for how we interpret this data.
Brand vs generic prescribing mix · Typical
Ann Mass, MD - brand share 15.0%
Specialist average
15% brand-name claims vs 84% generic, on 3,086 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.
3,086
Total Claims
$466K
Total Drug Cost
316
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 6,903
- Total Day Supply
- 202,253
- Brand vs Generic
- 15% brand / 84% generic
- Brand Drug Cost
- $393K
- Generic Drug Cost
- $72K
- Opioid Claims
- 15 (0.5% rate)
- Antibiotic Claims
- 71
Patient Demographics
- Average Patient Age
- 74.8 years
- Avg HCC Risk Score
- 0.77
- Gender Split
- 58% female / 42% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Ann Mass, MD prescribes most
Top Medicare Part D drugs by claim count, 2023
- Atorvastatin Calcium
Atorvastatin Calcium
225 claims
- Levothyroxine Sodium
Levothyroxine Sodium
166 claims
- Rosuvastatin Calcium
Rosuvastatin Calcium
151 claims
- Losartan Potassium
Losartan Potassium
111 claims
- Escitalopram Oxalate
Escitalopram Oxalate
106 claims
- Gabapentin 85
Gabapentin
85 claims
- Amlodipine Besylate 80
Amlodipine Besylate
80 claims
- Zolpidem Tartrate 78
Zolpidem Tartrate
78 claims
| Drug | Claims |
|---|---|
| Atorvastatin Calcium | 225 |
| Levothyroxine Sodium | 166 |
| Rosuvastatin Calcium | 151 |
| Losartan Potassium | 111 |
| Escitalopram Oxalate | 106 |
| Gabapentin | 85 |
| Amlodipine Besylate | 80 |
| Zolpidem Tartrate | 78 |
| Ezetimibe | 71 |
| Simvastatin | 55 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Specialist Overview
How Ann Mass, MD fits within the Specialist landscape nationally.
69,608
Specialist Providers in US
55
States with Specialist
1,474
Avg Claims per Provider
Ann Mass, MD's 3,086 claims are above the specialty average of 1,474.
Nearby Specialist Providers in Colorado
Other clinicians with the same primary specialty enrolled in Colorado, drawn from the same CMS NPPES roster as Mass.
Mack Abernathy
Aurora, CO
Moses Abraha
Aurora, CO
Dr. Barbara Abrahams
MD
Aurora, CO
Dr. Marcela Abuid
M.D.
Delta, CO
Dr. Gila Ackerman
M.D.
Boulder, CO
Compare Specialist 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 Colorado medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Specialist 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.
Healthcare Guides
Learn more about finding, verifying, and understanding healthcare providers.
How to Find a Doctor
Step-by-step guide to choosing a provider
Verify Credentials
Check NPI, board certification & license status
Medical Specialties Explained
Who treats what and how specialties differ
Understanding Medicare Claims Data
What prescribing data reveals about a provider
In-Network vs Out-of-Network
How insurance networks affect your costs
Telehealth Guide
Virtual care options and coverage in 2026
Explore Colorado
Frequently Asked Questions
What is Ann Mass, MD's specialty? ▼
Ann Mass, MD specializes in Specialist and practices in Aspen, Colorado. Credentials: MD.
How much does Ann Mass, MD prescribe under Medicare Part D? ▼
In 2023, Ann Mass, MD wrote 3,086 Medicare Part D claims totaling $466K in drug costs for 316 beneficiaries.
Where is Ann Mass, MD located? ▼
Ann Mass, MD is located at 225 N MILL ST, Aspen, CO, 81611. Phone: (970) 544-1234.
What is Ann Mass, MD's NPI number? ▼
Ann Mass, MD's National Provider Identifier (NPI) is 1598769358, issued on 06/09/2005.
Does Ann Mass, MD prescribe more brand-name or generic drugs? ▼
Ann Mass, MD's prescribing is 15% brand-name and 84% generic drugs by claim count, with $393K in brand drug costs.
Does Ann Mass, MD prescribe opioids? ▼
Yes, Ann Mass, MD had 15 opioid claims in 2023 with an opioid prescribing rate of 0.5%.
How many Specialist providers are there in the US? ▼
There are 69,608 Specialist providers across 55 states in the US. The average Specialist provider writes 1,474 Medicare Part D claims per year.
What drugs does Ann Mass, MD prescribe most often? ▼
Based on 2023 Medicare Part D data, Ann Mass, MD's most frequently prescribed drugs include Atorvastatin Calcium, Levothyroxine Sodium, Rosuvastatin Calcium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Ann Mass, MD accept Medicare? ▼
Ann Mass, MD appears in CMS Medicare data with 3,086 Part D claims and 316 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Ann Mass, MD's credentials? ▼
Ann Mass, MD's NPI is 1598769358 with credentials MD. 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.