Dirk Ross Diefendorf, M.D.
Sports Medicine (Neuromusculoskeletal Medicine) Physician · San Mateo, CA
Dirk Ross Diefendorf, M.D. is a sports medicine (neuromusculoskeletal medicine) physician with a practice address in San Mateo, California, and NPI 1467559443, issued on Sep 20, 2006. Check the license (California G53558, as entered in NPPES) with the California board that licenses this profession; the Medicare figures below come from public CMS files.
- Name
- Dirk Ross Diefendorf
- Credential
- M.D.
- Primary taxonomy
- Sports Medicine (Neuromusculoskeletal Medicine) Physician 204C00000X
- License number
- G53558 CA
Self-reported in NPPES; status is on the state search - Practice location
- 101 S Ellsworth Ave, San Mateo, CA 94401
- Phone
- (650) 347-0157
- Enumerated
- Sep 20, 2006
- Record last updated
- Aug 30, 2010 (not updated in 16 years: call before relying on the address or phone)
- Fax
- (650) 347-0566
- Medicare enrollment
- Enrolled (PECOS I20101013000318); accepts Medicare assignment
- Medical or professional school
- Northwestern University Feinberg Medical School, 1983
- Entity
- Type 1 · individual
8 nearest sports medicine (neuromusculoskeletal medicine) physician records → All 62 in California → Look up another NPI →
Verify Dirk Ross Diefendorf in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWhich California board licenses this profession
Search for license G53558Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
82% fewer Medicare Part D claims than the average sports medicine (neuromusculoskeletal medicine) physician in 2024
171 Medicare Part D claims for 86 beneficiaries, against an average of 965 among the 110 providers of this specialty who prescribed in Part D. 21 claims were for opioids.
Most prescribed
- Meloxicam62 claims
- Cephalexin26 claims
- Diclofenac Sodium20 claims
- Tramadol Hcl14 claims
- Nabumetone11 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 100 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Dirk Ross Diefendorf among 62 sports medicine (neuromusculoskeletal medicine) physician records in California
Dirk Ross Diefendorf, M.D. is one of 62 sports medicine (neuromusculoskeletal medicine) physician records with a practice address in California. 42% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 3% of them.
- NPI issued2006 · 3% of these records are older, 39% newer
- In a Medicare fileYes · 42% of these records are
- In the CMS Doctors and Clinicians fileYes · 34% of these records are
- Graduated1983 · median 1996 among the 21 with a school on file
- Record last updated2010 · 73% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 204C00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Sports Medicine (Neuromusculoskeletal Medicine) Physician providers in California
There are 62 sports medicine (neuromusculoskeletal medicine) physician records in California.
All 62 in California → Every provider in San Mateo → Sports Medicine (Neuromusculoskeletal Medicine) Physician nationwide →
The 8 sports medicine (neuromusculoskeletal medicine) physician records with the nearest ZIP codes
- Gordon Matheson, M.D., PH.D.Stanford, CA 943051255487518
- Roger KlimaPalo Alto, CA 943041528165958
- John Neely, MDSan Francisco, CA 941211508950213
- Joseph Haggerty, M.D.San Francisco, CA 941171215099882
- Jason Tokumoto, MDSan Francisco, CA 941101073670675
- George SwearingtonSan Francisco, CA 941091992389746
- John Horsley, P.T.Mountain View, CA 940431689615106
- Iqbal Maan, P.T.Mountain View, CA 940431922193739
Common questions
What is Dirk Ross Diefendorf, M.D.'s NPI number?
Dirk Ross Diefendorf, M.D.'s National Provider Identifier (NPI) is 1467559443, issued on Sep 20, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Dirk Ross Diefendorf, M.D. located?
The NPPES record lists a practice address at 101 S Ellsworth Ave, San Mateo, CA, 94401. Phone: (650) 347-0157. Providers update this record themselves, so call before visiting.
How can I verify Dirk Ross Diefendorf, M.D.'s license?
NPPES lists California license number G53558, as entered by the provider. Search the California board that licenses this profession; the NPPES record confirms identity only.
How much does Dirk Ross Diefendorf, M.D. prescribe under Medicare Part D?
In 2024, Dirk Ross Diefendorf, M.D. had 171 Medicare Part D claims for 86 beneficiaries; the average among sports medicine (neuromusculoskeletal medicine) physician prescribers was 965. Part D covers Medicare prescriptions only.
What is Dirk Ross Diefendorf, M.D.'s MIPS final score?
The 2023 MIPS final score is 100 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.