u/No_Bicycle_3660

This study just published in Risk Analysis is directly relevant to a debate that comes up a lot in this field: are we measuring access correctly, or are we measuring something that only loosely correlates with actual healthcare utilization?

Researchers at Cal Poly combined mobile phone mobility data with demographic and socioeconomic census data to model pharmacy foot traffic across LA County. Rather than relying on traditional geographic proximity metrics, they applied discrete choice theory to analyze where people actually go what they call *realized access* versus what's simply available nearby.

Here are the core finding:

• Nearly 98% of LA County residents had a pharmacy within 5km. Only 70% used one that close.
• Over a third of low-income residents visited pharmacies in low-income neighborhoods. Fewer than 7% sought care in higher-income areas.
• The pattern reflects strong social similarity in mobility — people consistently choose facilities in communities that demographically mirror their own.

This has direct implications for how we conduct needs assessments, allocate resources, and evaluate intervention effectiveness. If our access metrics don't account for social and behavioral determinants of utilization, we're likely underestimating unmet need in underserved populations and overestimating the impact of supply-side interventions like simply opening new facilities.

The researchers note the model extends beyond pharmacies to grocery stores and other essential services and could be particularly valuable for modeling access disruption during disaster events and public health emergencies.

So, I came across this study published in Risk Analysis, and it reframed how I think about healthcare access. Researchers at Cal Poly used real mobile phone movement data to track where people in LA County actually go to fill prescriptions and the results were pretty eye-opening.

Here's what stood out to me:

• Almost 98% of LA County residents had a pharmacy within 5km of their home. Only 70% actually used one that close. People are traveling further than they need to and it's not random.
• More than a third of low-income residents were going to pharmacies in low-income neighborhoods. Less than 7% crossed into wealthier areas for care. The researchers call this "social similarity" in mobility patterns basically; people go where they feel like they belong.
• 15.8 million Americans live in pharmacy deserts nationally. California alone has 2.5 million residents without real pharmacy access the most of any state. In LA County specifically, about 1 in 4 census tracts qualify as a pharmacy desert.

This feels like it goes way beyond pharmacies. If the same pattern holds for urgent care centers, mental health clinics, or even grocery stores, we might be systematically underestimating how hard it is for people in lower-income communities to access care even when it's technically "available."

Would love to hear from people who work in healthcare, public health, or urban planning. Is this something you've observed on the ground? And for everyone else — do you think about this when you choose where to get care?