When a clinical trial runs across two or more sites in the same metro area, every site’s radius overlaps with the others. Without geographic boundary management, your sites are bidding against each other in Google Ads auctions, inflating your own cost-per-click, and confusing patients who see different sites advertising the same trial. Multi-site geotargeting requires deliberate territory division — the same logic that prevents two salespeople from competing for the same account.
The Hidden Cost of Intra-Study Competition
In Google Ads, when two campaigns from the same advertiser account target the same geographic zone and bid on overlapping keywords, they do not compete with each other in the same auction — Google prevents this within a single account. But if your sites run separate accounts (common when different marketing vendors manage different sites), they bid against each other, driving up the cost-per-click for both. The study pays more for the same patient population. Consolidating multi-site campaigns into a single Google Ads account eliminates intra-study auction competition entirely.
Drawing Geographic Boundaries Between Sites
Define each site’s catchment territory using a Thiessen polygon approach: assign each patient inquiry to the nearest site based on patient ZIP code. The boundary between two sites’ territories is the set of points equidistant from both sites. This can be approximated manually by drawing a line midway between two sites on a map, or calculated precisely using free GIS tools like QGIS.
In practice: open Google Maps, find the midpoint between Site A and Site B, identify the ZIP codes on each side of that midpoint, and assign those ZIP codes exclusively to the corresponding site’s ad campaign.
Campaign Architecture for Multi-Site Trials
Best structure in a single Google Ads account:
- One campaign per site, with each campaign’s geographic targeting limited to that site’s exclusive ZIP code territory
- Shared budget strategy: allocate budget to each site proportionally to its enrollment capacity, not equally
- Separate conversion tracking per site so sponsor reports can attribute inquiries to the correct location
- Shared negative keyword list across all site campaigns to prevent keyword overlap from creating internal search ranking dilution
Handling the Boundary Zone
ZIP codes that sit on the boundary between two sites’ territories should be assigned to the site that is closer by drive time (not distance) from that ZIP code’s population center. Patients in boundary zones will generally drive to whichever site is more convenient; drive-time data makes that assignment more accurate than straight-line midpoints.
Patient Self-Selection and Redirect Protocol
Despite precise geographic targeting, some patients will contact the wrong site — their preferred site based on a referral, proximity to their workplace rather than home, or simply which ad they saw first. Establish a cross-site redirect protocol: if a patient contacts Site A but lives within Site B’s territory, offer to transfer their information to Site B with patient consent. Define which conditions trigger this (patient ZIP code in Site B’s zone) and which staff member handles the warm transfer.
48-Hour Action List
- Hour 1: Map your sites on Google Maps. Draw a rough boundary line at the midpoint between each pair of sites. Identify the ZIP codes on each side of every boundary. Create a ZIP code assignment spreadsheet: ZIP → Site A or Site B.
- Hour 2: If your sites use separate Google Ads accounts, evaluate consolidating them into one MCC (Manager Account). In Google Ads, go to ads.google.com/intl/en_us/home/tools/manager-accounts to create an MCC that manages all site accounts, preventing intra-auction bidding competition.
- Hour 3: In each site’s campaign, add all competing sites’ ZIP codes as excluded locations. This immediately stops each site from bidding on the other’s territory.
- Day 2: Write a one-page cross-site redirect protocol. Define the trigger (patient ZIP code in another site’s zone), the offer script (“We’d love to connect you with our [City] location — they may be even more convenient for you”), and who handles the transfer call.