The number of U.S. medical schools that have student-run free clinics has more than doubled during the past decade, with more than half of medical students involved with these clinics.

Researchers from the University of California at San Diego conducted a study to assess whether there has been growth of student-run free clinics (SRFCs) in medical schools and describe the characteristics of these clinics. The first national study of SRFCs conducted in 2005 described 111 SRFCs at 49 Association of American Medical Colleges (AAMC) member institutions.

For the recent study, Sunny Smith and colleagues developed a 39 item survey with yes/no, multiple-choice, and open-ended responses. SRFCs and their medical student leaders were identified through the Society of Student-Run Free Clinics.

They identified SRFCs at 106 of 141 (75.2 percent) U.S. AAMC member institutions. The survey response rate was 81.1 percent (86/106). The 86 responding institutions reported 208 SRFC sites. More than half of medical students were reported to be involved in SRFCs, including first- through fourth­ year students. Fifty-three percent of institutions reportedly offered no academic credit for participation.

The most common core services provided by the SRFCs were outpatient adult medicine, health care maintenance, chronic disease management, language interpreters and social work. The most common diseases treated were diabetes and hypertension.

In open-ended responses, students identified the greatest strengths of SRFCs as serving the underserved and student education. The biggest challenges were obtaining sufficient faculty staffing and funding.

"Despite the lack of academic credit at many institutions, most medical students are volunteering in this setting. Given the ubiquity of SRFCs in the education of future physicians, further research is needed to assess their educational and clinical outcomes," the authors write. "The lack of funding and sufficient faculty supervisors identified as the biggest challenges in SRFCs are actionable items because institutional support could help stabilize and improve these educational opportunities for years to come."

The findings are detailed in the journal JAMA.