Mary Parker Johnstone
Physician Assistant · Cambridge, MA
Mary Parker Johnstone is a physician assistant with a practice address in Cambridge, Massachusetts, and NPI 1639810807, issued on Apr 5, 2022. Check the license (Massachusetts PA9335, as entered in NPPES) with the Massachusetts board that licenses this profession; the Medicare figures below come from public CMS files.
- Name
- Mary Parker Johnstone
- Primary taxonomy
- Physician Assistant 363A00000X
- License numbers
- PA9335 MA
4930 TN
Self-reported in NPPES; status is on the state search - Practice location
- 1493 Cambridge St, Cambridge, MA 02139
- Phone
- (617) 665-1000
- Enumerated
- Apr 5, 2022
- Record last updated
- May 5, 2023
- Medicaid ID
- Q073493 TN
- Medicare enrollment
- Enrolled (PECOS I20230503001686); accepts Medicare assignment
- Medical or professional school
- University Of Tennessee, Hsc, College Of Medicine, 2021
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest physician assistant records → All 4,713 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 Mary Parker Johnstone in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWhich Massachusetts board licenses this profession
Search for license PA9335Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
73% fewer Medicare Part D claims than the average physician assistant in 2024
223 Medicare Part D claims for 181 beneficiaries, against an average of 830 among the 101,058 providers of this specialty who prescribed in Part D. Brand-name drugs were 29% of claims.
Most prescribed
- Gavilyte-G108 claims
- Peg-3350 And Electrolytes53 claims
- Colestipol Hcl12 claims
- Omeprazole12 claims
- Pantoprazole Sodium11 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 practice group's MIPS final score for 2023 (Medicare payment program): 75 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 2 group practices
- Cambridge Public Health CommissionEverett, MA
- Pratt Medical Group IncBoston, MA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mary Parker Johnstone among 4,713 physician assistant records in Massachusetts
Mary Parker Johnstone is one of 4,713 physician assistant records with a practice address in Massachusetts. 78% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2022, is newer than 68% of them.
- NPI issued2022 · 68% of these records are older, 25% newer
- In a Medicare fileYes · 78% of these records are
- In the CMS Doctors and Clinicians fileYes · 68% of these records are
- Graduated2021 · median 2019 among the 3,217 with a school on file
- Record last updated2023 · 38% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 363A00000X and a Massachusetts practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
99 physician assistant records list a practice address in Cambridge
They are 99 of the 5,145 NPPES records with a practice address in Cambridge, and 4,713 physician assistant records in Massachusetts.
All 4,713 in Massachusetts → Every provider in Cambridge → Physician Assistant nationwide →
The 8 physician assistant records with the nearest ZIP codes
- Elvira Aronzon, PA-CCambridge, MA 021391851358279
- Marita Barrett, PA-CCambridge, MA 021391801941323
- Mark Brady, PA-CCambridge, MA 021391649349994
- Allisyn Brady, PACambridge, MA 021391275686750
- Carla Dupont, PA-CCambridge, MA 021391053489096
- Catherine Faulkner, PACambridge, MA 021391811040389
- Kathleen Goreham, PA-CCambridge, MA 021391750410015
- Kenrith Plummer, PACambridge, MA 021391306867742
Common questions
What is Mary Parker Johnstone's NPI number?
Mary Parker Johnstone's National Provider Identifier (NPI) is 1639810807, issued on Apr 5, 2022. An NPI identifies a provider in billing; it is not a license.
Where is Mary Parker Johnstone 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 Mary Parker Johnstone's license?
NPPES lists Massachusetts license number PA9335, as entered by the provider. Search the Massachusetts board that licenses this profession; the NPPES record confirms identity only.
How much does Mary Parker Johnstone prescribe under Medicare Part D?
In 2024, Mary Parker Johnstone had 223 Medicare Part D claims for 181 beneficiaries; the average among physician assistant prescribers was 830. Part D covers Medicare prescriptions only.
What is Mary Parker Johnstone's MIPS final score?
The 2023 MIPS final score is 75 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.