RAY HSIAO, MD appears in the CMS NPPES registry as a Internal Medicine Physician provider holding MD credentials at 1850 S AZUSA AVE, HACIENDA HEIGHTS, CA, 91745, with a listed phone of (626) 854-7866. NPI 1164507869 was issued on 10/25/2006. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what HSIAO most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 16,623 prescription claims written by this provider, covering 766 Medicare beneficiaries and totaling roughly $3.3 million in drug spend, split 17% brand-name and 83% generic by claim count, with an opioid prescribing rate of 0.4%. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy. On the CMS Merit-based Incentive Payment System, this provider earned a Final Score of 79.9919/100 for the 2023 performance year (Quality 55.3012, Cost 76.238), compared with the national average of 83.1.

Internal Medicine Physician is a high-volume specialty nationwide, with 172,858 enrolled providers across 56 states and an average of 2,716 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.