Delwyn Lee Lassen, MD
Family Medicine Physician · Sioux Center, IA
Delwyn Lee Lassen, MD is a family medicine physician with a practice address in Sioux Center, Iowa, and NPI 1558346015, issued on Dec 7, 2005. Check the license (Iowa 21150, as entered in NPPES) on the Iowa Board of Medicine; the Medicare figures below come from public CMS files.
- Name
- Delwyn Lee Lassen
- Credential
- MD
- Primary taxonomy
- Family Medicine Physician 207Q00000X
- License number
- 21150 IA
Self-reported in NPPES; status is on the state search - Practice location
- 33 4TH St NW, Sioux Center, IA 51250
- Phone
- (712) 722-1700
- Enumerated
- Dec 7, 2005
- Record last updated
- Dec 15, 2020 (not updated in 6 years: call before relying on the address or phone)
- Fax
- (712) 722-1770
- Medicaid ID
- 1066548 IA
- Entity
- Type 1 · individual
8 nearest family medicine physician records → All 2,336 in Iowa → Look up another NPI →
Also registered at 33 4TH St NW
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Delwyn Lee Lassen in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersIowa Board of Medicine
Search for license 21150Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
99% fewer Medicare Part D claims than the average family medicine physician in 2024
36 Medicare Part D claims, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D.
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 MIPS final score for 2023 (Medicare payment program): 94 of 100
The Merit-based Incentive Payment System score is reported for this clinician. 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; category weights for 2023 (qpp.cms.gov).
Delwyn Lee Lassen among 2,336 family medicine physician records in Iowa
Delwyn Lee Lassen, MD is one of 2,336 family medicine physician records with a practice address in Iowa. 75% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 84% newer
- In a Medicare fileYes · 75% of these records are
- In the CMS Doctors and Clinicians fileNo · 59% of these records are
- Record last updated2020 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Q00000X and a Iowa practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
15 family medicine physician records list a practice address in Sioux Center
They are 15 of the 146 NPPES records with a practice address in Sioux Center, and 2,336 family medicine physician records in Iowa.
All 2,336 in Iowa → Every provider in Sioux Center → Family Medicine Physician nationwide →
The 8 family medicine physician records with the nearest ZIP codes
- Lorianne Andersen, MDSioux Center, IA 512501427279025
- Robert Clemens, MDSioux Center, IA 512501689734576
- Paul Dejong, MDSioux Center, IA 512501801096599
- Richard Jongewaard, MDSioux Center, IA 512501124188040
- Jason Koelewyn, MDSioux Center, IA 512501659592020
- Casie Leightner, MDSioux Center, IA 512501497172456
- Dale Nystrom, MDSioux Center, IA 512501528128444
- Mary Rayborn, MDSioux Center, IA 512501992865828
Common questions
What is Delwyn Lee Lassen, MD's NPI number?
Delwyn Lee Lassen, MD's National Provider Identifier (NPI) is 1558346015, issued on Dec 7, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Delwyn Lee Lassen, MD located?
The NPPES record lists a practice address at 33 4TH St NW, Sioux Center, IA, 51250. Phone: (712) 722-1700. Providers update this record themselves, so call before visiting.
How can I verify Delwyn Lee Lassen, MD's license?
NPPES lists Iowa license number 21150, as entered by the provider. Search the Iowa Board of Medicine at https://dial.iowa.gov/about-dial/boards-and-commissions/medicine. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Delwyn Lee Lassen, MD prescribe under Medicare Part D?
In 2024, Delwyn Lee Lassen, MD had 36 Medicare Part D claims; the average among family medicine physician prescribers was 3,544. Part D covers Medicare prescriptions only.
What is Delwyn Lee Lassen, MD's MIPS final score?
The 2023 MIPS final score is 94 of 100. 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.