Grudge Match: Pens vs. Syringes

Taking insulin is a cornerstone of care for millions who have diabetes, and the most common method of insulin delivery in the U.S. is injection via needle and syringe. Roughly 20% of insulin users wear an insulin pump, 15% use insulin pens, and less than 1% use jet injectors.

Insulin pumps can be expensive, with the average price hovering around $6,500, not including the disposable supplies that have to be replenished regularly, such as infusion sets, cartridges, and batteries. Although jet injectors may seem like a dream come true for patients who fear needles, they have been known to cause bruising and more pain than injections.

The big question is why insulin pens are not more popular in the U.S., whereas in Europe and Japan, they comprise from 66% to 75% of insulin prescriptions. It’s not for lack of patient appreciation: In the November 2011 issue of the Journal of Diabetes Science and Technology, a review of 43 studies that compared patient- reported outcomes for insulin pen devices found that patients preferred pens over vial and syringe for myriad reasons, including ease of use, less pain, and greater perceived social acceptance.

Indeed, patients are generally receptive to pen use — if their physicians bring it up. A study published in the March 2008 issue of Diabetes Care found that physician encouragement had a tremendous impact on pen use: Patients whose physicians discussed insulin pens were 100 times more likely to use an insulin pen than those whose physicians did not discuss pen use or who discouraged pen use.

One reason pens have not caught on here may be payer reimbursement, says Maria J. Redondo, MD, PhD, MPH, assistant professor of pediatrics at Baylor College of Medicine in Houston and co-author of the 43-study review. “Pens are more expensive than vial and syringe, and different insurance companies cover different pens depending on the formulary.”

Inconsistent insurance coverage seems counter- intuitive to Carl V. Asche, PhD, research professor of medicine and director of the Center for Outcomes Research at the University of Illinois College of Medicine at Peoria. Asche co-authored a review appearing in a supplement to the June 2010 issue of Diabetes Technology and Therapeutics that found an association between insulin pen use and greater patient adherence to insulin regimens and decreased use of healthcare resources and their associated costs compared to the use of vial and syringe.

“Managed care has not embraced pens here, but with- out factoring cost offsets for things like improved outcomes and lower overall healthcare costs [among insulin pen users], it’s not clear to me how insurers come to that decision,” says Asche.

Whether the Affordable Care Act will affect reimbursement for pens remains to be seen. In the meantime, physicians can work with their patients to determine whether pens might be more suitable than vial and syringe by keeping several key considerations in mind.

Dosing Factors

One advantage insulin pens offer is that they require fewer steps than vial and syringe. Although some pens require users to pop a cartridge in, most pens are disposable and come pre-filled with insulin. Users need only to check the cartridge to ensure there are no bubbles, prime the needle if there are, then dial up their dose and inject.
“Using a vial and syringe requires more steps and a larger skill set. The more steps there are, the more opportunities there are for mistakes,” says Linda Siminerio, RN, PhD, CDE, professor of medicine and executive director at the University of Pittsburgh Diabetes Institute.

Depending on the patient’s insulin needs and which pen or syringe is being used, the size of the dose can be a determining factor.

“Many of the 100-unit syringes are marked in two- unit increments. That won’t work for patients who take an odd number of units,” says Zachary Weber, PharmD, BCPS, BCACP, CDE, clinical assistant professor of pharmacy practice at the Purdue College of Pharmacy in Indianapolis. “Generally, I counsel pharmacy students to be wary about making odd-number unit recommendations, but it depends on how much insulin the person needs over- all. If someone takes 60 to 80 units per day, a one-unit difference may not matter. But if the person takes less than 20 units per day, it will make a difference.”

In such cases, pens that offer single-unit dosing may offer an advantage. In fact, several studies indicate that insulin pens are more accurate than syringes for doses of less than five units.

However, the vial and syringe method has one key advantage over pens, says Siminerio. “If you have to take two different types of insulin, you can’t mix them together in a pen. This will mean separate shots, which can be an issue for kids or anyone who wants to minimize their number of injections.”

Vision and Dexterity

Because pens are larger than syringes, require fewer steps in preparing injections, and produce a click that users can hear and feel as they dial a dose, they may be a better option for patients with impaired vision or dexterity, says Weber. But he noted one prominent exception: patients or caregivers who have arthritis.

“The plunger is larger in a pen than with a syringe, and pen needles tend to be a smaller gauge than needles used with syringes. That creates more resistance when pushing the plunger down, which can be a challenge for patients who have arthritis or joint problems in their hands, particularly in their thumbs,” Weber says.

He added that pens require a slightly longer injection time. “Pens require users to keep the needle under the skin for a few more seconds than syringes because of the difference in needle gauge. It takes longer for the liquid to be expelled with a pen,” Weber says. “Usually we tell pen users to count one-Mississippi-two-Mississippi up to five Mississippis for pens, versus three Mississippis for syringe.”

Two seconds may not seem like a big deal, but if pen users have tremors or lack hand strength, they may with- draw the needle too soon, insulin may leak out, and the patient’s blood glucose may remain high. If it happens enough, the patient may write the pen off as ineffective.

“This is the kind of thing clinicians don’t think about until they see a few thousand people with diabetes,” says Weber. “But it’s the details like this that can be why someone’s diabetes is not well-controlled.”

Addressing Misconceptions

Patients and physicians alike may have misconceptions or false assumptions about insulin pens.

“Some patients worry that the technology will make them harder to use,” says Redondo. “In the United States, the more technology-friendly patients tend to opt for insulin pumps, while those with less comfort with technology may prefer to stay with vial and syringe.”

Other patients may assume too much of insulin pens, says Weber. “I’ve seen patients who think that using a pen negates the need to check their blood glucose. They will do anything they can to minimize the burden of pricking their fingers and checking their blood glucose, but there is no evidence that using a pen makes a difference.”

Physicians may have misconceptions about pen needles, as well, particularly with respect to their patients with type 2 diabetes, says Siminerio. “There’s an assumption that obese patients need longer needles, but the fact is that longer needles will go intramuscular instead of subcutaneous, so shorter needles are reported to be safer,” she says.

Siminerio adds that there is often confusion when it comes to prescribing needles. “Everyone expects someone else to prescribe the needle size. Physicians think the pharmacist will do it, pharmacists think the physician will do it, and the patient shows up at the pharmacy and ends up with whatever is available. Physicians need to remember to prescribe the needle size and think small.”

Redondo points out that the sheer number of insulin pens on the market can make it difficult for physicians to keep track of them all. “There can be a lack of familiarity with specific pens and what they can do. If physicians had that familiarity, they would be more likely to prescribe pens.”

One way to address this challenge is to consult with diabetes educators, Redondo says. “They tend to know all the newest pens and their features.”

Physicians who prescribe insulin pens should steer their patients toward diabetes educators from the start, says Siminerio. “Patients in several focus groups across demographics — African American, Latino, Caucasian — have all said that it would be better to have an in-person demonstration of how to use a pen before they go to the pharmacy. That’s where you can rely on educators.”

Money Talks

In the end, insurance coverage may be the deciding factor when choosing between pens and vial and syringe, says Redondo. “A physician may want to prescribe a pen, but maybe the patient’s insurance plan covers some pens, but not all of them, or not pens that would be most suitable for that particular patient. That will be more paperwork for the patient and physician with obtaining prior authorization.”

When it comes to expense, forewarned is forearmed, says Siminerio.

“Endocrinologists, primary care physicians, nurse practitioners, pharmacists — everyone needs information on cost. Too often, patients get a prescription for insulin therapy and when they get to the pharmacy that’s when they find out how much it costs,” Siminerio says. “Comparing pens to syringes is not as simple as saying one is better than the other. Expense can be problematic for pens.”

— D’Arrigo is a health and science writer based in Holbrook, N.Y., and a regular contributor to Endocrine News. She wrote about treating diabetes accompanied by celiac disease in the February issue.

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