Nicholas Gaston Callihan, M.D.
Emergency Medicine Physician · Houston, TX
Nicholas Gaston Callihan, M.D. is an emergency medicine physician with a practice address in Houston, Texas, and NPI 1821482357, issued on Mar 23, 2015. Check the license (Texas R6532, as entered in NPPES) on the Texas Medical Board; the Medicare figures below come from public CMS files.
- Name
- Nicholas Gaston Callihan
- Credential
- M.D.
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- R6532 TX
Self-reported in NPPES; status is on the state search - Practice location
- 1635 North Loop W, Houston, TX 77008
- Phone
- (713) 867-2000
- Enumerated
- Mar 23, 2015
- Record last updated
- Sep 13, 2024
- Medicare enrollment
- Enrolled (PECOS I20180416000371); accepts Medicare assignment
- Medical or professional school
- Medical College Of Georgia School Of Medicine, 2015
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 4,885 in Texas → Look up another NPI →
Also registered at 1635 North Loop W
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Nicholas Gaston Callihan in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersTexas Medical Board
Search for license R6532Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
19% fewer Medicare Part D claims than the average emergency medicine physician in 2024
182 Medicare Part D claims for 148 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. 24 claims were for opioids.
Most prescribed
- Cephalexin20 claims
- Prednisone16 claims
- Hydrocodone-Acetaminophen14 claims
- Ondansetron Odt12 claims
- Tizanidine Hcl11 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): 82.4 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).
Industry payments in 2024: $20.90
1 payment: food and beverage; the largest payer was Salix Pharmaceuticals, a division of Bausch Health US, LLC. The 12,335 providers of this specialty with any payment received $953.79 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through 2 group practices
- Memorial Hermann Hospital Based Physician GroupHouston, TX
- UT PhysiciansHouston, TX
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Nicholas Gaston Callihan among 4,885 emergency medicine physician records in Texas
Nicholas Gaston Callihan, M.D. is one of 4,885 emergency medicine physician records with a practice address in Texas. 83% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2015, is newer than 67% of them.
- NPI issued2015 · 67% of these records are older, 30% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileYes · 57% of these records are
- Graduated2015 · median 2013 among the 2,779 with a school on file
- Record last updated2024 · 55% 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 Texas practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
818 emergency medicine physician records list a practice address in Houston
They are 818 of the 61,221 NPPES records with a practice address in Houston, and 4,885 emergency medicine physician records in Texas.
All 4,885 in Texas → Every provider in Houston → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- Ross Bauer, MDHouston, TX 770081932125879
- Michael Bublewicz, M.D.Houston, TX 770081083941819
- Harparminder Chadha, M.D., FACEPHouston, TX 770081770508137
- Elizabeth Edwards, M.D.Houston, TX 770081689691123
- Habacuc Garcia, M.D.Houston, TX 770081316964877
- Vanessa Garza-Miranda, M.D.Houston, TX 770081073861233
- Davida Manor, M.D.Houston, TX 770081427138114
- Maricruz Medina-Marquis, M.D.Houston, TX 770081598780926
Common questions
What is Nicholas Gaston Callihan, M.D.'s NPI number?
Nicholas Gaston Callihan, M.D.'s National Provider Identifier (NPI) is 1821482357, issued on Mar 23, 2015. An NPI identifies a provider in billing; it is not a license.
Where is Nicholas Gaston Callihan, M.D. located?
The NPPES record lists a practice address at 1635 North Loop W, Houston, TX, 77008. Phone: (713) 867-2000. Providers update this record themselves, so call before visiting.
How can I verify Nicholas Gaston Callihan, M.D.'s license?
NPPES lists Texas license number R6532, as entered by the provider. Search the Texas Medical Board at https://profile.tmb.state.tx.us/Search.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Nicholas Gaston Callihan, M.D. prescribe under Medicare Part D?
In 2024, Nicholas Gaston Callihan, M.D. had 182 Medicare Part D claims for 148 beneficiaries; the average among emergency medicine physician prescribers was 226. Part D covers Medicare prescriptions only.
What is Nicholas Gaston Callihan, M.D.'s MIPS final score?
The 2023 MIPS final score is 82.4 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.