Nurse practitioner Bill LaRock tells Sean Mullen that he should consider treatment for his hepatitis C, but an even greater concern is the stubborn and robust cigarette habit that Mullen, 46, a recovering heroin addict, seems reluctant to kick.

"The cigarettes are a bigger risk for you right now," LaRock said recently in a gigantic Project Renewal Care Van parked outside the Doe Fund's "Ready, Willing & Able" program on Frederick Douglass Boulevard in Harlem. Mullen had come to the CareVan to obtain blood test results. But LaRock reminded him that smoking damages vascular health and "is also a primary factor in erectile dysfunction."

"The erectile part is OK. I don't like that word 'dysfunction,'" Mullen said with a wide grin. The two chatted about Mullen's smoking history ("I started as an embryo") and other priorities -- maintaining his 30-day sobriety, staying out of jail and getting a troublesome tooth extracted -- that interfere with Mullen kicking cigarettes. "I've got eight patches," said Mullen, adding with a sigh, "Don't ask me why I started again." Quitting, he finally acknowledged, "is just a matter of doing it."

In its 48-year-history, Project Renewal has grown to become one of the largest providers of health care to the city's burgeoning homeless population (more than 60,000 people at last count), serving more than 10,700 patients in fiscal year 2014. Offering comprehensive services from psychiatry to dental care, caregivers find themselves in the cross section of contentious health care issues, from the skyrocketing cost of many medications to the effectiveness of the Affordable Care Act (ACA).

Rotating through 18 different locations, the four "CareVans" deliver care to the homeless where many live: In the streets. The skyrocketing cost of drugs -- even generic drugs -- is troubling for people at all economic levels, but especially their patients. "I have a guy with MRSA (a contagious bacteriological infection) who needs to take doxycycline every day prophylactically," but the price has skyrocketed from $10 for a month's supply to about $300, said LaRock.

The ACA has made it easier for patients to obtain both coverage and care, according to the team: Virtually all the homeless and insecurely housed people who patronize Project Renewal are eligible for Medicaid, save for undocumented patients. Once enrolled in Medicaid, a patient's name can go into a large database "so all the hospitals can check your info," which reduces the risk of mistakes and improves outcomes, explained medical technician Felipe De Jesus.

A downside? As Medicaid's rolls have expanded, more patients are having a tough time accessing specialists, noted medical director Dr. Roslynn Glicksman. But coverage also permits patients to fill exacting prescriptions, rather than relying solely on the basic supplies of antibiotics, diabetes and blood pressure meds that the van keeps on hand, she said. And if you need an additional reason to support NYC's small businesses, Project Renewal works with independent pharmacies throughout the city, many of which waive copays for Project patients, Glicksman noted.

There are other factors driving up costs for the poor. Recently, 23 people -- including nine doctors -- were indicted in Brooklyn for enticing homeless people with sneakers in order to submit $7 million worth of phony Medicaid claims, according to prosecutors. Health care fraud not only disrupts trust between providers and patients, but victimizes suffering patients.

Homeless patients tell the Project Renewal team there is another van traveling the city with people who offer them""$20 to see the dentist," probably to be able to submit fraudulent Medicaid bills, said Glicksman. "They come to our dentist and want $20," thinking it is normal for patients to be paid. "I had a patient who came to me with a report of three different tests he didn't need and said, 'Somebody asked me if I wanted to get these tests and they'd pay me $20 for each test.' It's so immoral," Glicksman added.

Project Renewal is seeing more older patients "with lots of chronic medical conditions," which are difficult to manage for folks without a kitchen to keep and prepare healthy foods, a safe place to keep meds, a dependable bathroom to cleanse open wounds or a reliable rack in which to rest, noted Glicksman. Shelters "are trying to feed the guys on limited budgets -- with pasta and rice and things like that," and many of the men living in the streets have only enough money to buy high carb foods -- "all that stuff fueling the epidemic," of obesity and diabetes, LaRock added.

"The population we deal with has been dealt a terrible hand, and a lot of them have given up. One of the things they've given up on is their health," explained Victor Franco, Project Renewal's outreach and enrollment coordinator. But high quality health care can be transformative: Developing mastery over one's blood pressure or blood sugar opens the door to empowerment in other situations, be it making amends to loved ones or landing a job. "It's about control," as LaRock explained. And, of course, people do better when they feel better physically.

"If this stuff isn't taken care of, I can't go to work," explained Mullen, who has worked as a brick layer, construction worker and hair dresser before addiction toppled his life. "I have all this guilt to deal with," concerning his marriage, which crumpled under the weight of his addiction, as well as his two "good kids," who suffered as well, Mullen explained. But now he is motivated to improve himself. "This place has been a godsend," in helping him do so, he said.