Tamara Beetham, PhD, MPH

Job market paper

Clinician Supply, Market Structure, and Primary Care Access: A National Audit

Tamara Beetham, Jane M. Zhu, Nicholas King, and Michael L. Barnett

Wait times for a new Medicare appointment, across and within metropolitan areas

Mean wait time, by metropolitan area

Phoenix, AZMinneapolis, MNLittle Rock, ARNew York, NYDenver, COSt. Louis, MORichmond, VAAlbuquerque, NMProvidence, RIPortland, ME

Range across clinics within each area

0 50 100 150 200 Wait time (days) New York, NY Denver, CO St. Louis, MO Little Rock, AR Minneapolis, MN Phoenix, AZ Richmond, VA Albuquerque, NM Providence, RI Portland, ME 280 metropolitan areas, ordered by mean
Clinics with observed wait time 104080
Not called
Mean wait time (days) 102030405060
10th to 90th percentile
Area mean
Overall mean
In the map, each dot is a metropolitan area, color shows the mean wait time in days, and dot area reflects the number of clinics with an observed wait time. Hatched states require all-party consent to call recording and were not called. In the range chart, each column is a metropolitan area, ordered by mean wait time; bars span the area's 10th to 90th percentile across clinics, and the dashed line is the mean across all clinics. Clinic wait times are capped at the 99th percentile of the national distribution. Unadjusted.

Abstract

There is concern over a shortage of primary care clinicians in the US. However, there is little evidence on where new patients can get an appointment or what explains variation in access across markets. We used AI voice agents to conduct a simulated-patient audit of 12,935 eligible primary care clinics in 280 metropolitan statistical areas (MSAs) in 2026. The caller asked whether the clinic accepted new Medicare patients and the wait time until the soonest appointment. We estimated associations of wait time with clinician supply, parent organization (firm) market share of Medicare patients, competing firms, and clinic and population characteristics. Overall, 81% of clinics accepted new Medicare patients, and the mean wait time was 31 days (median 14). Mean wait times were 12 days in the 10th percentile MSA and 55 days in the 90th. Clinics in MSAs with more primary care clinicians per 100,000 residents did not have shorter wait times (+2.3 days per SD; 95%CI, −0.05, 4.7). Wait times were longer at clinics whose firm treated a larger share of the market's Medicare patients (+7.1 days per SD; 95%CI, 5.2, 9.0) and shorter in markets with more competing firms (−4.6 days per SD; 95%CI, −6.8, −2.5). After adjustment, firm market share remained the strongest association (+5.2 days per SD; 95%CI, 3.2, 7.2), accounting for 22% of explained variance. Wait times for new Medicare patients varied widely across metropolitan areas and were better explained by firm market share and competition than clinician supply.

JEL codes: I11, I18, J44, L11 Keywords: primary care access, audit study, wait times, market structure, clinician supply, Medicare, AI voice agents

Mean wait time by clinician supply and by firm market share

Clinician supply
20 30 40 50 255075100125 Clinicians per 100,000 residents Mean wait time (days)

+2.3 days per SD (95% CI, −0.05 to 4.7)

Firm market share
20 30 40 50 0204060 Firm market share of Medicare patient volume (%) Mean wait time (days)

+7.1 days per SD (95% CI, 5.2 to 9.0)

Clinics offering an appointment (n = 7,691) are sorted on each measure and split into 20 equal-count bins. Each point is a bin's mean wait time, and the line is a least-squares fit to the individual clinics. Gray bars show the distribution of clinics, and the horizontal axis ends at the 99th percentile. Estimates are unadjusted, per standard deviation, with standard errors clustered by metropolitan area.

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