It never fails. That nagging cough always seems to get worse on the weekend when your doctor’s office is closed. Sure, your condition may not be life-threatening, but you’d still like some medical treatment without having to go to the emergency room.

In response to that demand, the number of urgent care centers on the Eastside and across the country continues to rise.

Data Source: based on 2010 Medica Choice Network claims

Data Source: based on 2010 Medica Choice Network claims

Over the last two decades, urgent care centers have been used by the medical industry to fill the gap between after-hour sore throats and life-threatening conditions fit for the emergency room. Nationally, there are an estimated 9,400 urgent care centers. In 2013, the market for such services hit $14 billion, according to the medical research firm Kalorama Information.

The urgent care trend is strong on the Eastside, as well. In January, patients were given another urgent care option when Overlake Hospital opened its third Eastside urgent care center. It’s housed in the medical company’s Bellevue primary care clinic at 400 108th Ave. NE.

Dr. Eric Shipley, medical director of Overlake’s urgent care centers, says the need for such a service is rising.

“We have more patients who need medical care at nontraditional hours that are convenient to their schedule,” he says. “Many people work long hours and can’t be evaluated during the business’ operations.”

Urgent care centers offer services similar to primary care facilities, but are open in the evenings and on the weekends. Most employ both medical doctors and physician assistants, who are trained to treat many common ailments.

Because Overlake’s new Bellevue urgent care center is housed in the same 6,000-square-foot facility as its primary care clinic, it can borrow rooms when the other service is closed. The shared space allows Overlake to provide services to the booming downtown workforce without finding a new location in the expensive downtown core.

The reciprocal relationship works because the urgent care center is typically busiest in the late afternoon and early evenings when the primary care clinic is winding down its operations or closed, Shipley says.

Overlake’s Redmond and Issaquah urgent care centers do not share space. However, all patient information is linked through the company’s computer system, so an urgent care patient’s information can be sent to his or her primary care doctor for follow up within the system.

Most urgent care centers treat any patient, regardless of whether the patient is part of its health care network.

Other health care companies offer similar centers on the Eastside. EvergreenHealth has urgent care centers in Redmond and Woodinville. Both are located inside medical centers with adjacent primary care clinics.

Similarly, Group Health runs an urgent care center in its Bellevue location that is open 24/7. In addition, Group Health also has CareClinics in some Bartell Drugs locations. These CareClinics allow patients to receive walk-in care for basic maladies, at a set price, while they are running errands, says Group Health spokesperson Jackson Holtz.“We want to provide as many options as possible for patients to access our care and have a positive experience,” Holtz says.

Dr. Kevin Hanson, director of EvergreenHealth’s emergency medicine, believes the number of urgent care centers will continue to grow.

“Both locally and nationally, patients are increasingly seeking same-day access to doctor’s appointments when they don’t feel well,” he says. “As more patients are becoming insured, in some cases, there are fewer primary care appointments available on a same-day basis.”

Bruce Carlson, Kalorama’s publisher, says urgent care is important for medical companies as well. At one time, urgent care centers were mostly independent companies. Now, hospitals and larger medical groups are getting in the game.

Urgent care centers take business away from both primary care clinics and emergency rooms, he says. In addition, many insurance companies favor urgent care clinics to avoid the higher expense of emergency rooms.

According to Carlson, 90 percent of urgent care visitors have a regular physician they have seen in the last year. He says the unresolved question is whether urgent care is taking visitors away from their primary care doctors or creating visits from people who wouldn’t ordinarily be seen because the doctor’s office is too busy. One trend that troubles physicians is that some patients are beginning to use urgent care for things like physicals and flu shots.

Overlake’s Shipley points out the increase in urgent care visits may be attributed to the lack of doctors nationwide.

“We have a significant dearth of primary care doctors in our country that will only intensify over the next 20 years,” he says. “Also, patients increasingly have insurance but may not have a physician whom they can see for primary care. Many of these patients will seek out urgent care to address their health care needs when they spontaneously arise.”