Build a physician audience by specialty and geography
Audience building for healthcare usually means buying a list of uncertain provenance. This is the federal registry, so you can see exactly where every field came from.
Segment on what actually matters
Specialty by NUCC taxonomy rather than a vendor's invented categories, credential, practice geography, solo versus group, and how recently they registered.
Direct mail
Practice addresses are public and postal. The export includes address, city, state and ZIP in separate columns, ready for a mail house.
Suppression and hygiene
Because you can re-pull the same segment weekly, you can see what changed rather than mailing a list that quietly decays.
What this data will not tell you
NPPES is public domain and may be used commercially, but how you contact people is governed separately. Faxes to providers are regulated by the TCPA and junk-fax rules, and several states add their own restrictions on commercial email and calls. The fax numbers in this data are published for clinical use. Take your own legal advice before running a campaign.