Experts estimate that by 2020, the United States will have a deficit of 85,000 physicians, with a disproportionate shortage of doctors willing to care for the poor. As images of hospitals overflowing with patients, doctors overwhelmed with work and the sick languishing in pain begin to resemble reality more than science fiction, recruiting more doctors to care for the underserved becomes essential.

“If you can pinpoint doctors’ motivating factors, we can perhaps tailor policy or recruitment strategies to address the shortage,” said Lydia Dugdale, professor of internal medicine at the Yale School of Medicine.

A recent study co-authored by Dugdale reports that doctors who have a religious affiliation or frequently attend religious services are no more likely to care for underserved patients than their non-religious counterparts, indicating that religious affiliation alone is not enough to motivate doctors to serve.

Because many doctors who care for poor populations consider their work a “calling,” a concept often associated with the Christian, Muslim, Buddhist, Jewish and Hindu faiths, Dugdale said she and her colleagues wondered whether doctors who described themselves as religious were more likely to report caring for the underserved.

“Working with poor populations comes with many difficulties — less opportunity for advancement, bad pay, long hours — it’s not sexy,” said Dugdale. Some other impulse must inspire doctors to leave their comfortably air-conditioned offices.

The study, which appeared in the July/August issue of the Annals of Family Medicine, employs data from surveys sent out to 2,000 United States physicians in a variety of specialties. The surveys measured doctors’ religiosity, their spirituality, the degree to which they considered medicine a calling and whether they grew up in families that prioritized helping the poor. The data also revealed the proportion of doctors who worked in underserved communities.

While physicians who were more religious by traditional standards — those who are affiliated with an organized religion or attend services frequently — did not disproportionately serve the poor, those who grew up in families that emphasized service or who reported no religious leanings at all were more likely to care for the poor than their religious counterparts. Physicians who described themselves as spiritual or agreed that religion informed their practice were also more likely to care for underserved patients.

“I can’t tell you the number of conversations I’ve had with people who say ‘I’m not religious, but I feel that there are things that are bigger than us, that I can’t explain, that drive my decisions,’” said University Chaplain Sharon Kugler. “Organized religion may not play a role.”

Richard Selzer, a former School of Medicine professor and a renowned medical writer, said that while he is opposed to organized religion, he believes that faith informs the practice of medicine.

“Even in my skepticism and disbelief, I do feel that spirituality is something than can be used to help the sick and unfortunate,” Selzer said.

In recent years, media reports on such topics as stem cells and evolution have cast science and religion as enemies tussling for truth and morality. Dugdale hypothesized that the study’s results could be due in part to this illusion of incompatibility.

“Physicians don’t want the image that they depend on religion,” Dugdale said. “But at the end of the day, the majority do.”

On the other hand, Kugler said that many doctors explain their desire to serve the poor as appealing to their sense of social justice or commitment to humanity. Yet in interviewing applicants to Johns Hopkins School of Medicine, where she was formerly chaplain, Kugler said she was struck by the spirituality of applicants’ feelings about what it means to be in a healing profession. She remembers the way one young man described his experience riding in an ambulance in the toughest part of Baltimore.

“He said he felt like he was touching the holy when he was with people who had nothing and who were touching the void between life and death,” Kugler said.

Perhaps if potential premeds could experience something so profound, whether it appealed to their spirituality or their sense of duty, they would march up Science Hill with more vigor — and in greater numbers.