Colin Diffie, MD
NPI 1942616404 · Rheumatology Physician · Saint Louis, MO
Enrolled with Medicare as Practitioner - Rheumatology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Colin Diffie, MD is a Rheumatology Physician provider in Saint Louis, MO (NPI 1942616404).
Provider details
- NPI number
- 1942616404
- Entity type
- Individual
- Primary specialty
- Rheumatology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- 2019017299 (MO)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
11 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)25% of score
609 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 274 | $120 |
| Infusion Into a Vein for Therapy, Prevention, Or Diagnosis, 1 Hour Or Less96365 | 66 | $59 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 58 | $87 |
| Injection of Drug Or Substance Under Skin Or Into Muscle96372 | 48 | $14 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 28 | $63 |
| Established Patient Office Or Other Outpatient Visit With High Level of Medical Decision Making, If Using Time, 40 Minutes Or More |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 42 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Prednisone | 327 | 83 |
| Methotrexate Sodiumbrand: Methotrexate | 273 | 67 |
| Hydroxychloroquine Sulfate | 231 | 63 |
| Adalimumabbrand: Humira(cf) Pen | 79 | — |
| Mycophenolate Mofetil | 66 | 16 |
| Hydrocodone/Acetaminophenbrand: Hydrocodone-Acetaminophen | 65 | — |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$3,089 across 18 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Additional practice locations (1)
- 4921 Parkview PlDiv Im Rheumatology, Ste 5cSaint Louis, MO 63110-1032Phone: (314) 286-2635Fax: (314) 286-2338
Registry dates
- Enumerated
- 2014-07-05
- Last updated
- 2025-09-11
- Certified
- 2025-09-11
Frequently asked questions
- What is Colin Diffie's NPI number?
- Colin Diffie's National Provider Identifier (NPI) is 1942616404, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Colin Diffie's specialty?
- Colin Diffie is listed in the NPPES registry with a primary specialty of Rheumatology Physician (Allopathic & Osteopathic Physicians).
- Where is Colin Diffie located?
- Colin Diffie's practice location on file with NPPES is 915 N Grand Blvd, Saint Louis, MO 63106-1621.
- What is Colin Diffie's phone number?
- The practice phone number listed in the NPPES registry for Colin Diffie is (314) 652-4100.
- Does Colin Diffie accept Medicare?
- Colin Diffie is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Colin Diffie's NPI active?
- Yes — Colin Diffie's NPI (1942616404) is active in the NPPES registry as of the last update on 2025-09-11.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.