Mark B Oechsli , PA-C
Physician Assistant • Simi Valley, CA
4531 Alamo St, Sierra Vista Family Medical Clinic
Simi Valley, CA 93063
This profile restates public CMS/NPPES data; T-MedInfo gives no medical advice — consult a licensed professional, and call 911 for emergencies.
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NPI assigned on August 29, 2005; this date does not establish years in practice.
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Published CMS data list 136 Medicare Part D prescriptions, including refills, in 2024.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024. Published rows only; this is not a quality measure.
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Published Part D records, 2024:
- Atorvastatin Calcium — 35 prescription fills, including refills.
- Hydrochlorothiazide — 14 prescription fills, including refills.
- Metoprolol Succinate — 14 prescription fills, including refills.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024. Drug names come from pharmacy claims. Listing a drug here is not an endorsement or a recommendation.
See all 9 records in the table · Guide: How to read Medicare Part D prescriber data
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Fewer Part D prescriptions than 80% of clinicians listed under Physician Assistant in Simi Valley, CA (2024, 21 clinicians with data). Median for this group: 480. Middle half: 162 to 894.
Fewer Part D prescriptions than 60% of clinicians listed under Physician Assistant in California (2024, 7,516 clinicians with data). Median for this group: 229. Middle half: 72 to 718.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024. Billing and prescribing volume is not a quality rating.
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Medicare Part D prescriptions went from 1,167 in 2020 to 136 in 2024.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2020–2024.
Practice Location & Contact Primary Location
4531 Alamo St
Sierra Vista Family Medical Clinic
Simi Valley, CA 93063
NPPES lists 1 additional practice-address record in Thousand Oaks, CA. See the list
Source: CMS NPPES NPI Registry, practice location records; release date unavailable.
Listings do not confirm current availability, employment or a shared ownership network.
What Public CMS Data Show
Physician Assistant: NPPES taxonomy is a reported classification, not proof of board certification.
30-day fills
199 standardized 30-day fills in 2024
CMS converts prescriptions to 30-day supplies so they can be compared. A 90-day prescription counts as about three 30-day fills.
What this does not show: 30-day fills
It is not a count of patients and not a measure of quality.
Part D drug cost
$12,199 in 2024
The total cost of these prescriptions in 2024, paid by Medicare drug plans, patients and other payers together.
It shows the total spending on drugs this clinician prescribed, not what any one patient paid.
What this does not show: Part D drug cost
A higher cost often reflects the type of medicines a specialty uses. It is not your out-of-pocket cost and not a measure of quality.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024.
Industry payments (Open Payments)
No Open Payments records are listed for this clinician for 2021–2025.
NPI first issued
2005
The year this clinician's National Provider Identifier (NPI) was issued. An NPI is a unique 10-digit ID that US health care providers use for billing.
What this does not show: NPI first issued
NPIs have been issued only since 2005, so this year is not necessarily when the clinician started practicing.
Source: CMS NPPES NPI Registry.
Medicare assignment not listed
CMS data do not show whether this clinician accepts Medicare assignment. This does not mean they do not accept Medicare. Ask the office.
Medicare assignment applies to Original Medicare. It does not tell you whether the clinician is in a Medicare Advantage plan's network, accepts other insurance, or is taking new patients.
Source: CMS Doctors and Clinicians; Medicare.gov, “Does your provider accept Medicare as full payment?”
No telehealth indicator
CMS shows this indicator only when recent Medicare claims include telehealth services. The clinician may still offer telehealth; ask the office.
Source: CMS, Telehealth Indicator on Medicare Care Compare (fact sheet, January 2023); CMS Doctors and Clinicians.
Enrolled in Medicare (PECOS)
Mark Oechsli has a Medicare enrollment record in PECOS, the CMS system clinicians use to enroll so they can bill Medicare or order services for people with Medicare.
It does not show whether the clinician accepts assignment, is in your plan's network, or is taking new patients.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Can order Medicare-covered services
CMS lists Mark Oechsli as eligible to order or refer durable medical equipment (DME) for people with Medicare.
Medicare pays for these items and services only when they are ordered by an eligible clinician.
What this does not show: Can order Medicare-covered services
It does not mean the clinician offers these services directly.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Compared with the same specialty in Simi Valley and California
Billing and prescribing volume is not a quality rating.
Medicare Part D prescriptions
Fewer Part D prescriptions than 80% of clinicians listed under Physician Assistant in Simi Valley, CA (2024, 21 clinicians with data). Median for this group: 480. Middle half: 162 to 894.
Fewer Part D prescriptions than 60% of clinicians listed under Physician Assistant in California (2024, 7,516 clinicians with data). Median for this group: 229. Middle half: 72 to 718.
Part D drug cost
A higher Part D drug cost than 60% of clinicians listed under Physician Assistant in Simi Valley, CA (2024, 21 clinicians with data). Median for this group: $3,412. Middle half: $1,237 to $22,516.
A higher Part D drug cost than 60% of clinicians listed under Physician Assistant in California (2024, 7,516 clinicians with data). Median for this group: $3,945. Middle half: $709 to $60,209.
35 active clinicians are listed under Physician Assistant with a practice address in Simi Valley, CA (14,458 in California).
Addresses are self-reported to NPPES and may be out of date.
Telehealth indicator in Simi Valley
8.6% of these 35 clinicians have the CMS telehealth indicator.
45.7% of these 35 clinicians are listed by CMS as accepting Medicare assignment.
CMS data by year
Changes may reflect reporting, coverage or privacy limits, not changes in care quality.
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Medicare Part D prescriptions
Medicare Part D prescriptions decreased 88% from 1,167 in 2020 to 136 in 2024.
- 2020: 1,167
- 2021: 1,049
- 2022: 1,102
- 2023: 785
- 2024: 136
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30-day fills
30-day fills decreased 90% from 2,069 in 2020 to 199 in 2024.
- 2020: 2,069
- 2021: 1,792
- 2022: 1,983
- 2023: 1,359
- 2024: 199
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Part D drug cost
Part D drug cost decreased 85% from $80,354 in 2020 to $12,199 in 2024.
- 2020: $80,354
- 2021: $26,408
- 2022: $56,531
- 2023: $44,157
- 2024: $12,199
Sources: CMS Medicare Part D Prescribers (2024), CMS Doctors and Clinicians, CMS NPPES NPI Registry. Specialty names follow the NUCC Health Care Provider Taxonomy.
Text: T-MedInfo · Report an error.
Medicare Part D Prescribing Profile & Medications
Medicare Part D prescriptions filled, including refills, in 2024.
| Brand Name | Generic Name | Prescriptions | Day Supply | Total Cost | Patients |
|---|---|---|---|---|---|
| Atorvastatin Calcium | Atorvastatin Calcium | 35 | 1,592 | $326.33 | — |
| Hydrochlorothiazide | Hydrochlorothiazide | 14 | 600 | $8.32 | — |
| Metoprolol Succinate | Metoprolol Succinate | 14 | 600 | $296.29 | — |
| Furosemide | Furosemide | 13 | 390 | $107.31 | — |
| Omeprazole | Omeprazole | 12 | 975 | $200.38 | — |
| Potassium Chloride | Potassium Chloride | 12 | 360 | $138.14 | — |
| Benazepril Hcl | Benazepril Hcl | 12 | 720 | $47.09 | — |
| Rivastigmine | Rivastigmine | 12 | 360 | $1,724.07 | — |
| Entresto | Sacubitril/Valsartan | 12 | 360 | $9,351.34 | — |
Source: CMS Part D by Provider and Drug, 2024; rows below 11 claims omitted by CMS; volume isn’t quality. Privacy limits
Specialties & License Numbers Reported to NPPES
Self-certified to NPPES: 2023-07-17NUCC Taxonomy Code: 363A00000X
A physician assistant is a person who has successfully completed an accredited education program for physician assistant, is licensed by the state and is practicing within the scope of that license. Physician assistants are formally trained to perform many of the routine, time-consuming tasks a physician can do. In some states, they may prescribe medications. They take medical histories, perform physical exams, order lab tests and x-rays, and give inoculations. Most states require that they work under the supervision of a physician.
Medicare (PECOS) Enrollment & Ordering Eligibility
Source: CMS PECOSPRACTITIONER - PHYSICIAN ASSISTANT
I20080630000425
CA
8426120825
Sources: CMS Provider Enrollment and Order and Referring. Medicare enrollment is a billing status, not an accreditation or quality rating.
Secondary Practice Locations
125 W Thousand Oaks Blvd Ste 300
Thousand Oaks, CA 913604460
Phone: 8054189100
Clinicians Sharing This Practice Address or Phone
Clinicians sharing this NPPES address, phone or fax; a shared contact does not mean they work together.
Physician Assistant - Medical
Physician Assistant (Certified)
Family Medicine
Doctor of Medicine (M.D.)
Career & Practice History
NPI enumerated August 29, 2005.
No changes to the name, practice address, taxonomy or NPI status in this record have been observed in the monthly NPPES data files from January 2017 to August 2026.
NPI Administrative Meta
Other Physician Assistants in Simi Valley
- Ryan Vickers, PA-C, MMS
- Brenda Mcalpin, PA-C
- Nazaneen Cauthron, PA-C
- Robert Fielding, PA
- Luke Paik, PA-C
- Andrew Schott, PA-C
Mailing Address
5738 Skyview Way, Unit G
Agoura Hills, CA 91301
Phone: 8187060483