Dr. Matthew Alexander Stack , MD
Internal Medicine - Infectious Disease โข Houston, TX
6431 Fannin St # 2.112
Houston, TX 770301501
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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Dr. Matthew Stack is listed in NPPES under Internal Medicine - Infectious Disease.
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NPI assigned on May 31, 2018; this date does not establish years in practice.
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Published CMS data list 29 Original Medicare Part B services in 2024.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024. Published rows only; this is not a quality measure.
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Published Part B service records, 2024:
- 99233 โ Subsequent hospital care with moderate levelof medical decision making: 29 service units.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024. Units differ by code; these are not visits or a measure of quality.
CPTยฎ only copyright 2023 American Medical Association. All rights reserved. Service names are shortened from CPT Consumer Friendly Descriptors (CMS data, 2024). CPT notice
See the full table ยท Guide: How to read Medicare Part B data
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Published CMS data list 63 Medicare Part D prescriptions, including refills, in 2024.
Source: CMS, Medicare Part D Prescribers โ by Provider and Drug, 2024. Published rows only; this is not a quality measure.
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Published Part D records, 2024:
- Fluconazole โ 25 prescription fills, including refills.
- Isoniazid โ 15 prescription fills, including refills.
- Cephalexin โ 12 prescription fills, including refills.
Source: CMS, Medicare Part D Prescribers โ by Provider and Drug, 2024. Drug names come from pharmacy claims. Listing a drug here is not an endorsement or a recommendation.
See all 4 records in the table ยท Guide: How to read Medicare Part D prescriber data
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Fewer Medicare Part B services than 90% of clinicians listed under Internal Medicine - Infectious Disease in Houston, TX (2024, 90 clinicians with data). Median for this group: 309. Middle half: 186 to 1,279.
Fewer Medicare Part B services than 95% of clinicians listed under Internal Medicine - Infectious Disease in Texas (2024, 440 clinicians with data). Median for this group: 521. Middle half: 195 to 1,503.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024. Billing and prescribing volume is not a quality rating.
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Medicare Part D prescriptions went from 126 in 2020 to 63 in 2024.
Source: CMS, Medicare Part D Prescribers โ by Provider and Drug, 2020โ2024.
Practice Location & Contact Primary Location
6431 Fannin St # 2.112
Houston, TX 770301501
Matched by practice address or phone in NPPES. A shared address or phone does not confirm that this clinician works there.
NPPES lists 2 distinct additional practice-address records in Indianapolis, IN; Saint Louis, MO. See the list
Source: CMS NPPES NPI Registry, practice location records; release date unavailable.
CMS Doctors and Clinicians lists 2 distinct group names: Physician Services Corporation Of Southern Illinois Inc; Ssm Health Care Group. See the list
Source: CMS Doctors and Clinicians National Downloadable File, release date unavailable.
Listings do not confirm current availability, employment or a shared ownership network.
Medicare Profile & Education
Source: CMS Doctors and Clinicians National Downloadable File
Wayne State University School Of Medicine
2018
What Public CMS Data Show
Internal Medicine - Infectious Disease: NPPES taxonomy is a reported classification, not proof of board certification.
Medicare patients
21 people with Original Medicare in 2024
It gives a sense of how many people with Medicare this clinician treated that year.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider, 2024.
Medicare-allowed amount
About $3,300 in 2024
The total amount Medicare approved for these services in 2024. It includes what Medicare paid and what patients or their other insurance owed, such as the deductible and coinsurance.
It shows the total cost of this clinician's Original Medicare services under Medicare's fee rules.
What this does not show: Medicare-allowed amount
This is not the clinician's income. Part of it can go to a clinic or group practice, staff, equipment or drugs. It is not the price you will pay.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024.
Paid by Medicare
About $2,629 in 2024
The part of the Medicare-allowed amount that Medicare itself paid in 2024, after patients' deductibles and coinsurance.
The gap between the allowed amount and this number is roughly what patients and their other insurance paid.
What this does not show: Paid by Medicare
This is not the clinician's income and not a measure of quality.
Source: CMS, Medicare Physician & Other Practitioners โ by Provider and Service, 2024.
30-day fills
83 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
$837 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 โ by Provider and Drug, 2024.
Open Payments general payments, program year 2025
All general payments: $1,020.45 across 12 records.
By nature of payment
- Food and Beverage: $1,020.45 across 12 records.
Reporting-company totals (3 largest of 6)
- ViiV Healthcare Company: $442.09 across 4 records.
- Gilead Sciences, Inc.: $361.53 across 3 records.
- Merck Sharp & Dohme LLC: $133.42 across 1 record.
A reported payment does not necessarily mean the financial relationship is improper and is not a measure of care quality. Clinicians can review and dispute these records.
Source: Calculated by T-MedInfo from CMS Open Payments general-payment records for program year 2025 (published June 30, 2026).
Years since graduation
8 years (graduated 2018)
CMS Doctors and Clinicians data list 2018 as the year this clinician finished professional school.
It tells you roughly how long ago the clinician finished school.
What this does not show: Years since graduation
It is not the number of years in practice, and more years does not mean better care.
Source: CMS Doctors and Clinicians National Downloadable File.
NPI first issued
2018
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.
Accepts Medicare assignment
CMS data list this clinician as accepting Medicare assignment. This means agreeing to take the Medicare-approved amount as full payment for covered services.
With Original Medicare, you usually pay only your deductible and coinsurance, and the office sends the claim to Medicare for you.
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, โDoes your provider accept Medicare as full payment?โ
Telehealth (some services)
Recent Medicare claims show this clinician provided some services by telehealth, such as a video or phone visit.
You may be able to have some visits without going to the office. Ask which visits can be done by telehealth.
What this does not show: Telehealth (some services)
It does not mean all services are offered by telehealth, or that telehealth is covered by your plan.
Source: CMS, Telehealth Indicator on Medicare Care Compare (fact sheet, January 2023); CMS Doctors and Clinicians.
Enrolled in Medicare (PECOS)
Dr. Stack 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 Dr. Stack as eligible to order or refer Medicare Part B clinical laboratory and imaging services, durable medical equipment (DME) and home health services 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 Houston and Texas
Billing and prescribing volume is not a quality rating.
Medicare Part B services
Fewer Medicare Part B services than 90% of clinicians listed under Internal Medicine - Infectious Disease in Houston, TX (2024, 90 clinicians with data). Median for this group: 309. Middle half: 186 to 1,279.
Fewer Medicare Part B services than 95% of clinicians listed under Internal Medicine - Infectious Disease in Texas (2024, 440 clinicians with data). Median for this group: 521. Middle half: 195 to 1,503.
Medicare-allowed amount
A lower Medicare-allowed amount than 90% of clinicians listed under Internal Medicine - Infectious Disease in Houston, TX (2024, 90 clinicians with data). Median for this group: $38,578. Middle half: $18,685 to $119,028.
A lower Medicare-allowed amount than 90% of clinicians listed under Internal Medicine - Infectious Disease in Texas (2024, 440 clinicians with data). Median for this group: $56,021. Middle half: $19,952 to $149,490.
Paid by Medicare
A lower Medicare payment amount than 90% of clinicians listed under Internal Medicine - Infectious Disease in Houston, TX (2024, 90 clinicians with data). Median for this group: $30,578. Middle half: $14,846 to $94,087.
A lower Medicare payment amount than 90% of clinicians listed under Internal Medicine - Infectious Disease in Texas (2024, 440 clinicians with data). Median for this group: $44,053. Middle half: $15,577 to $117,748.
Medicare Part D prescriptions
Fewer Part D prescriptions than 70% of clinicians listed under Internal Medicine - Infectious Disease in Houston, TX (2024, 99 clinicians with data). Median for this group: 184. Middle half: 63 to 527.
Fewer Part D prescriptions than 80% of clinicians listed under Internal Medicine - Infectious Disease in Texas (2024, 428 clinicians with data). Median for this group: 280. Middle half: 89 to 664.
Part D drug cost
A lower Part D drug cost than 90% of clinicians listed under Internal Medicine - Infectious Disease in Houston, TX (2024, 99 clinicians with data). Median for this group: $179,528. Middle half: $40,737 to $649,618.
A lower Part D drug cost than 95% of clinicians listed under Internal Medicine - Infectious Disease in Texas (2024, 428 clinicians with data). Median for this group: $198,730. Middle half: $47,632 to $717,763.
155 active clinicians are listed under Internal Medicine - Infectious Disease with a practice address in Houston, TX (682 in Texas).
Addresses are self-reported to NPPES and may be out of date.
Telehealth indicator in Houston
31% of these 155 clinicians have the CMS telehealth indicator.
75.5% of these 155 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 B services
CMS data for Medicare Part B services are available for 2024 only.
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Medicare-allowed amount
CMS data for Medicare-allowed amount are available for 2024 only.
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Paid by Medicare
CMS data for Medicare payment amount are available for 2024 only.
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Medicare Part D prescriptions
Medicare Part D prescriptions decreased 50% from 126 in 2020 to 63 in 2024.
- 2020: 126
- 2021: 27
- 2022: 12
- 2023: 33
- 2024: 63
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30-day fills
30-day fills decreased 60% from 208 in 2020 to 83 in 2024.
- 2020: 208
- 2021: 41
- 2022: 12
- 2023: 33
- 2024: 83
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Part D drug cost
Part D drug cost decreased 89% from $7,671 in 2020 to $837 in 2024.
- 2020: $7,671
- 2021: $376
- 2022: $44,727
- 2023: $127,222
- 2024: $837
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Industry payments (Open Payments)
Industry payments (Open Payments) stayed about the same: $1,090.86 in 2024 and $1,020.45 in 2025.
- 2024: $1,090.86
- 2025: $1,020.45
Sources: CMS Medicare Physician & Other Practitioners (2024), CMS Medicare Part D Prescribers (2024), CMS Open Payments (2025), CMS Doctors and Clinicians, CMS NPPES NPI Registry. Specialty names follow the NUCC Health Care Provider Taxonomy.
Text: T-MedInfo ยท Report an error.
Pharma & Medical Device Financial Disclosures
Payments and other transfers of value that drug and medical device companies reported to CMS Open Payments
Program year 2025 (payments made January 1 โ December 31, 2025): 12 records totaling $1,020.45.
| Manufacturer | Payment Nature | Product | Type | Amount ($) |
|---|---|---|---|---|
| Gilead Sciences, Inc. |
Food and Beverage
In-kind items and services
|
Biktarvy | General | $146.17 |
| Merck Sharp & Dohme LLC |
Food and Beverage
In-kind items and services
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ZERBAXA | General | $133.42 |
| ViiV Healthcare Company |
Food and Beverage
In-kind items and services
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APRETUDE | General | $125.49 |
| ViiV Healthcare Company |
Food and Beverage
In-kind items and services
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โ | General | $123.67 |
| Gilead Sciences, Inc. |
Food and Beverage
In-kind items and services
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โ | General | $112.71 |
| ViiV Healthcare Company |
Food and Beverage
In-kind items and services
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โ | General | $108.20 |
| Gilead Sciences, Inc. |
Food and Beverage
In-kind items and services
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โ | General | $102.65 |
| ViiV Healthcare Company |
Food and Beverage
In-kind items and services
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CABENUVA | General | $84.73 |
| Cycle Pharmaceuticals Inc |
Food and Beverage
Cash or cash equivalent
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Sajazir | General | $25.16 |
| Paratek Pharmaceuticals, Inc. |
Food and Beverage
In-kind items and services
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NUZYRA | General | $23.35 |
| Melinta Therapeutics, LLC |
Food and Beverage
In-kind items and services
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Rezzayo | General | $18.55 |
| Melinta Therapeutics, LLC |
Food and Beverage
In-kind items and services
|
Orbactiv | General | $16.35 |
Source: CMS Open Payments, program year 2025, released June 30, 2026.
Performed Procedures & Service Volume
CPTยฎ is a registered trademark of the American Medical Association. CPT codes, descriptions and other data only are copyright 2023 American Medical Association. All rights reserved. Applicable FARS/HHSARS apply. Descriptions of CPT codes are the AMA's CPT Consumer Friendly Descriptors as published by CMS in the Medicare Physician & Other Practitioners โ by Provider and Service data, 2024; they are plain-language summaries, not for clinical coding or documentation. HCPCS Level II codes and descriptions are from CMS. Fee schedules, relative value units, conversion factors and/or related components are not assigned by the AMA, are not part of CPT, and the AMA is not recommending their use. The AMA does not directly or indirectly practice medicine or dispense medical services. The AMA assumes no liability for data contained or not contained herein.
| HCPCS Code | Services | Patients | Submitted Charge | Medicare Allowed |
|---|---|---|---|---|
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99233
Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes
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29 | 11 | $179.00 | $113.78 |
Source: CMS Part B by Provider and Service, 2024; services under 11 beneficiaries omitted by CMS. Privacy limits
Submitted charges are billed amounts, not a price quote for your visit.
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 |
|---|---|---|---|---|---|
| Fluconazole | Fluconazole | 25 | 870 | $578.43 | โ |
| Isoniazid | Isoniazid | 15 | 638 | $51.76 | โ |
| Cephalexin | Cephalexin | 12 | 480 | $173.41 | โ |
| Amoxicillin | Amoxicillin | 11 | 411 | $32.93 | โ |
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: 2024-05-19NUCC Taxonomy Code: 207RI0200X
An internist who deals with infectious diseases of all types and in all organ systems. Conditions requiring selective use of antibiotics call for this special skill. This physician often diagnoses and treats AIDS patients and patients with fevers which have not been explained. Infectious disease specialists may also have expertise in preventive medicine and travel medicine.
NUCC Taxonomy Code: 390200000X
An individual who is enrolled in an organized health care education/training program leading to a degree, certification, registration, and/or licensure to provide health care.
Medicare (PECOS) Enrollment & Ordering Eligibility
Source: CMS PECOSPRACTITIONER - INFECTIOUS DISEASE
I20240809000740
MO
5991050577
Sources: CMS Provider Enrollment and Order and Referring. Medicare enrollment is a billing status, not an accreditation or quality rating.
Medicare Group Practice Enrollments
Source: CMS Doctors and Clinicians National Downloadable File
Ssm Health Care Group
1225 S Grand Blvd, Saint Louis, MO 631041016
Phone: 3149779050
Physician Services Corporation Of Southern Illinois Inc
1 Good Samaritan Way, Mount Vernon, IL 628642402
Phone: 6182424600
Secondary Practice Locations
1008 S Spring Ave
Saint Louis, MO 631102520
Phone: 3146173137
1120 W Michigan St
Indianapolis, IN 462025209
Phone: 3172782694
Clinicians Sharing This Practice Address or Phone
Clinicians sharing this NPPES address, phone or fax; a shared contact does not mean they work together.
Internal Medicine - Infectious Disease
Doctor of Medicine (M.D.), Master of Public Health
Student in an Organized Health Care Education/Training Program
Doctor of Medicine (M.D.)
Internal Medicine
Doctor of Medicine (M.D.)
Internal Medicine - Infectious Disease
Doctor of Medicine (M.D.)
Student in an Organized Health Care Education/Training Program
Doctor of Medicine (M.D.)
Internal Medicine - Infectious Disease
Doctor of Medicine (M.D.), Bachelor of Medicine, Bachelor of Surgery (M.B.B.S.)
Career & Practice History Timeline
Changes recorded in monthly NPPES data files: addresses, names, credentials, specialties and NPI status
Registered at 6431 FANNIN ST # 2.112, HOUSTON, TX 770301501 (Tel: 7135006765)
Registered at 6431 FANNIN ST # 2.112, HOUSTON, TX 770301501 (Tel: 7135006765)
Additional practice office at 1008 S Spring Ave, Saint Louis, MO 631102520
Additional practice office at 1120 W Michigan St, Indianapolis, IN 462025209
Internal Medicine (license number reported to NPPES: TX BP10082502)
Student in an Organized Health Care Education/Training Program (license number reported to NPPES: IN 11020118A)
NPI status registered as active in NPPES database
Registered at 1120 W MICHIGAN ST, INDIANAPOLIS, IN 462025209 (Tel: 3172782694)
Registered at 1120 W MICHIGAN ST, INDIANAPOLIS, IN 462025209 (Tel: 3172782694)
Recorded as MATTHEW STACK, MD
Student in an Organized Health Care Education/Training Program
First registered as active Individual Practitioner in NPPES Database.
NPI Administrative Meta
Other Internal Medicine - Infectious Diseases in Houston
- Dr. Natalie Vanek, MD
- Dr. Patrycja Ashley, MD
- Dr. Jennifer Whitaker, MD
- Dr. Dierdre Axell-House, MD
- Dr. Rita Igwilo-Alaneme, MD
- Dr. Krithika Srinivasan, MD
Mailing Address
6431 Fannin St # 2.112
Houston, TX 770301501
Phone: 7135006765