Quick answers
- Does Zachary S. Sager accept Medicare assignment?
- Yes. Medicare's clinician data says Zachary S. Sager accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Zachary S. Sager see?
- In 2024, CMS data shows 97 Original Medicare patients and 259 services for Zachary S. Sager. This counts Original Medicare only and measures volume, not quality.
- What is Zachary S. Sager's NPI number?
- 1396183125. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Zachary S. Sager, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 97 |
|---|---|
| Services billed to Medicare | 259 |
| Different services or procedures | 15 |
| Participating Medicare provider | Yes |
| Average age of these patients | 70 |
Most frequent services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)115 services
- Telephone medical discussion with physician, 21-30 minutes (99443)42 services
- Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes (99231)13 services
- New patient office or other outpatient visit with a high level of medical decision making, if using time, 60 minutes or more (99205)12 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure68%
- High cholesterol67%
- Anxiety61%
- Cancer (breast, colorectal, lung, prostate, endometrial or leukemia/lymphoma)59%
- Depression46%
- Arthritis41%
Practice locations
Addresses where Zachary S. Sager is enrolled with Medicare (CMS data updated October 2, 2026).
- 450 Brookline AveBoston, MA 02215
Group practices
Medicare enrollment lists Zachary S. Sager as a member of this group (CMS data updated October 2, 2026).
- Dana-Farber Cancer Institute, Inc.684 clinicians in the group
Specialties
- Psychiatryprimary
- Hospice/Palliative Carealso
Other psychiatrists in Boston
Clinicians with the same Medicare primary specialty in Boston, MA — not a recommendation.
Other clinicians in Dana-Farber Cancer Institute, Inc.
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2013 (13 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1396183125 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians