IndividualActiveAccepts Medicare

William O'Callahan, MD

NPI 1114964186 · Emergency Medicine Physician · Holden, MA

Enrolled with Medicare as Practitioner - Emergency Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)

Provider details

NPI number: 1114964186
Entity type: Individual
Primary specialty: Emergency Medicine PhysicianAllopathic & Osteopathic Physicians
Credential: MD
Sex: Male
Sole proprietor: No
License: 79001 (MA)

Specialties & taxonomies

Emergency Medicine PhysicianPrimary207P00000XLicense 79001 (MA)
Allopathic & Osteopathic Physicians

Profile Score

Detailed profile(100/100 index)

A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.

Registry tenure28% of score
20 yrs in NPPES registry
Profile completeness28% of score
100% of core fields populated
Practice footprint17% of score
4 documented practice locations
Medicare service volume (vs. specialty peers)28% of score
988 Medicare services, 2024 (ranked within specialty)

Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.

What this provider does (Medicare)

Based on Medicare fee-for-service claims, 2024; not all care is captured.

Service (HCPCS)	Medicare services	Typical Medicare-allowed (2024)
Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213	188	$92
Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214	179	$130
X-Ray of Chest, 2 Views71046	121	$32
New Patient Office Or Other Outpatient Visit With Low Level of Medical Decision Making, If Using Time, 30 Minutes Or More99203	88	$112
New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204	86	$165
Detection Test By Multiplex Amplified Probe Technique for Severe Acute Respiratory Syndrome Coronavirus 2 (sars-Cov-2) (covid-19) and Influenza Virus Types a and B

What this provider prescribes (Medicare Part D)

Top drugs by Medicare Part D claim volume, 2024 · 16 distinct drugs on file.

Drug	Part D claims (2024)	Beneficiaries
Doxycycline Hyclate	144	138
Ibuprofen	128	126
Azithromycin	123	122
Prednisone	58	57
Nitrofurantoin Monohyd/M-Crystbrand: Nitrofurantoin Mono-Macro	43	43
Amoxicillin/Potassium Clavbrand: Amoxicillin-Clavulanate Potass	33	32
Cephalexin	31	30

Practice location

5 Shrewsbury St Ste D

Holden, MA 01520-1960

Phone: (508) 829-3800

Fax: (508) 829-3802

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Mailing address