Justin David Larson, M.D.
Emergency Medicine Physician · Cambridge, MA
Justin David Larson, M.D. is an emergency medicine physician with a practice address in Cambridge, Massachusetts, and NPI 1821319393, issued on Jun 18, 2010. Check the license (Massachusetts 266658, as entered in NPPES) on the Massachusetts Board of Registration in Medicine; the Medicare figures below come from public CMS files.
- Name
- Justin David Larson
- Credential
- M.D.
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- 266658 MA
Self-reported in NPPES; status is on the state search - Practice location
- 1493 Cambridge St, Cambridge, MA 02139
- Phone
- (617) 665-1000
- Enumerated
- Jun 18, 2010
- Record last updated
- Dec 20, 2020 (not updated in 6 years: call before relying on the address or phone)
- Medicare enrollment
- Enrolled (PECOS I20161130000335); accepts Medicare assignment
- Medical or professional school
- Saint Louis University School Of Medicine, 2010
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 1,829 in Massachusetts → Look up another NPI →
Also registered at 1493 Cambridge St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Omar Abbas, MDStudent in an Organized Health Care Education/Training Program1225728025
- Nawyaab Abbasi, DOStudent in an Organized Health Care Education/Training Program1215875364
- Flannery AbbeySocial Worker1508604273
- Rana AbdallahSocial Worker1689220204
- Khaleel Abdul-Jabbaar, PT, DPTOrthopedic Physical Therapist1780295717
- Adri Abou-Bakr, MDStudent in an Organized Health Care Education/Training Program1770421844
Verify Justin David Larson in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMassachusetts Board of Registration in Medicine
Search for license 266658Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
81% fewer Medicare Part D claims than the average emergency medicine physician in 2024
42 Medicare Part D claims for 28 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D.
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 practice group's MIPS final score for 2023 (Medicare payment program): 86.3 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. 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, group reporting; category weights for 2023 (qpp.cms.gov).
Bills Medicare through 4 group practices
- Beth Israel Lahey Health Specialty Care, Inc.Burlington, MA
- Bid-Milton Physician Associates IncMilton, MA
- Cambridge Public Health CommissionSomerville, MA
- Harvard Medical Faculty Phys AT Beth Israel Deaconess Med Ctr IncBoston, MA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Justin David Larson among 1,829 emergency medicine physician records in Massachusetts
Justin David Larson, M.D. is one of 1,829 emergency medicine physician records with a practice address in Massachusetts. 82% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2010, is newer than 56% of them.
- NPI issued2010 · 56% of these records are older, 41% newer
- In a Medicare fileYes · 82% of these records are
- In the CMS Doctors and Clinicians fileYes · 66% of these records are
- Graduated2010 · median 2011 among the 1,200 with a school on file
- Record last updated2020 · 57% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207P00000X and a Massachusetts practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
42 emergency medicine physician records list a practice address in Cambridge
They are 42 of the 5,145 NPPES records with a practice address in Cambridge, and 1,829 emergency medicine physician records in Massachusetts.
All 1,829 in Massachusetts → Every provider in Cambridge → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- Miriam Aschkenasy, M.D.Cambridge, MA 021391518939503
- Paul Chen, MD, MBACambridge, MA 021391154488898
- Slava Gaufberg, MDCambridge, MA 021391568537652
- Alex Goldstein, M.D.Cambridge, MA 021391255566949
- Irvin Heifetz, MDCambridge, MA 021391811062946
- Edward Lee, M.D.Cambridge, MA 021391689846578
- Luis Lobon, M.D., M.S.Cambridge, MA 021391033156799
- Benjamin Milligan, M.D.Cambridge, MA 021391104867233
Common questions
What is Justin David Larson, M.D.'s NPI number?
Justin David Larson, M.D.'s National Provider Identifier (NPI) is 1821319393, issued on Jun 18, 2010. An NPI identifies a provider in billing; it is not a license.
Where is Justin David Larson, M.D. located?
The NPPES record lists a practice address at 1493 Cambridge St, Cambridge, MA, 02139. Phone: (617) 665-1000. Providers update this record themselves, so call before visiting.
How can I verify Justin David Larson, M.D.'s license?
NPPES lists Massachusetts license number 266658, as entered by the provider. Search the Massachusetts Board of Registration in Medicine at https://findmydoctor.mass.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Justin David Larson, M.D. prescribe under Medicare Part D?
In 2024, Justin David Larson, M.D. had 42 Medicare Part D claims for 28 beneficiaries; the average among emergency medicine physician prescribers was 226. Part D covers Medicare prescriptions only.
What is Justin David Larson, M.D.'s MIPS final score?
The 2023 MIPS final score is 86.3 of 100, reported for the practice group. 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.