Replaced CMS quality rating proxy with official LA County EMS stroke certification data for 51 LA County hospitals. This is the first step toward full EMNet certification integration statewide.
The original Stroke Access Score pipeline used CMS Hospital Compare overall quality ratings (1–5 stars) as a proxy for stroke center certification — assigning CSC to 5-star hospitals, TSC to 4-star hospitals, and PSC to all others. This was an explicit approximation, documented in the methodology, pending access to authoritative certification data.
This update replaces that proxy for LA County hospitals with the LA County EMS Approved Stroke Center Directory — the official list of facilities verified by the county's Emergency Medical Services agency. For the 51 hospitals matched, the tier assignment now reflects actual certification level rather than a quality rating estimate.
EMNet national stroke certification data remains pending and will trigger a full statewide update when it arrives.
Key reclassifications resulting from the EMS directory match:
| Change | Cause | ZIP codes affected | Representative areas |
|---|---|---|---|
| +50 | PSC → CSC | 7 ZIPs | UCI Health Lakewood/Los Alamitos, MemorialCare Long Beach, USC Arcadia, Pomona Valley, Antelope Valley, UCSF St. Francis |
| +40 | ASRH → CSC | 9 ZIPs | High Desert / Antelope Valley |
| +25 | TSC → CSC | 180+ ZIPs | Long Beach, Pasadena/SGV, Glendale/Burbank, San Fernando Valley, Ventura County, Napa/Bay Area |
| +10 to +35 | Various upgrades | 29 ZIPs | Rural Kern, Mojave, Sierra foothills |
| −25 | TSC → PSC | 17 ZIPs | SE LA County, Downey corridor, Valley PSCs |
| −50 | CSC → PSC | 7 ZIPs | Central/East Hollywood corridor (90004, 90005, 90010, 90020, 90027, 90029, 90038) |
Four corrections made in this update: TSC removed statewide as a proxy artifact; five non-certified LA County hospitals removed; eight hospitals missing from CMS added from the EMS directory; and the scoring model revised to a CSC-weighted structure with 15-minute drive time increments. Score decreases reflect more accurate data, not degraded care.
TSC was assigned by CMS quality rating proxy only. LA County EMS and California EMS practice recognize only CSC and PSC. 63 hospitals nulled. 635 ZIPs re-scored. All changes flat or negative.
5 hospitals removed — not present on the LA County EMS Approved Stroke Center Directory (July 28, 2025):
Eight hospitals present in the LA County EMS directory were absent from the CMS dataset and added manually with drive-time collection.
The previous model used a flat penalty structure. The revised model weights CSC access heavily with 15-minute drive time increments and a major penalty beyond 60 minutes. PSC provides modest mitigation only.
| Drive Time | CSC Before | CSC After | PSC Before | PSC After |
|---|---|---|---|---|
| 0–15 min | 100 | 100 | 50 | 40 |
| 15–30 min | 100 | 85 | 50 | 32 |
| 30–45 min | 70 | 65 | 35 | 24 |
| 45–60 min | 70 | 50 | 35 | 16 |
| >60 min | 55 | 25 | 20 | 8 |
303 of 312 LA County ZIP codes scored. 9 excluded as non-residential:
Update #3 will integrate EMNet national stroke certification data statewide, replacing all remaining CMS proxy ratings for hospitals outside LA County. This will be the most significant data update and will trigger a full re-score of all 1,802 California ZIP codes.
| Region | Certification Source | ZIP Codes | Status |
|---|---|---|---|
| LA County | LA County EMS Directory (July 2025) | — | Current |
| Rest of California | CMS hospital data (proxy, TSC removed) | — | Pending EMNet |
| National | Not yet scored | — | Paper 2 |
Total ZIP codes scored statewide: —