Chronic pain patients already have enough to worry about from adverse drug events, but a new study highlights a possibly overlooked concern – their costs.

According to a recent study published by Pergolizzi et al. in the May 2014 article in the Journal of Managed Care & Specialty Pharmacy, already vulnerable chronic pain patients could end up paying 22 percent more per month in medical costs if exposed to opioid drug interactions.

The economic hardships of adverse drug events caused by drug-drug interactions on chronic pain patients taking opioids have already been well-established, with some studies cited by Pergolizzi et al. indicating overall health care cost increases can vary from $250 to as much as $1,200 over six months. Research indicates that adverse drug events affect millions of patients each year, or roughly 5 percent of hospital admissions.

With this research already on the books, Pergolizzi sought to determine costs of major, potentially-major drug-drug interactions in long-acting opioids. The researchers found that chronic pain patients taking long-acting opioids who had a drug-drug interaction paid $609 per month over a 90-day period than similar patients. Costs were tallied from all payments for covered healthcare services over the 90-day observation period and included inpatient and outpatient medical, ER visits and prescription costs.

The most common drug combination reported among patients in the study was fluconazole and oxycodone, both of which interact via the body’s CYP450 pathway. Drug interactions using this pathway are among the most common and potentially avoidable. A prescription for one of these analgesics does not guarantee the patient will experience a potentially major drug-drug interaction, but patients taking analgesics not metabolized by CYP450 are more likely to avoid a potentially major interaction.

Though only 5.7 percent of the 57,752 patients in this study were exposed to potential major drug-drug interactions, Pergolizzi et al. argue that intervention and management for this relatively small number of patients has the potential to drastically reduce the seemingly out-of-proportion difference in medical costs between those exposed and those not.

With both the health of chronic pain patients’ bodies and pocketbooks on the line, full knowledge of their drug regimen is essential for physicians. Click here to learn more about Genelex’s innovative approach to pharmacogenetic testing.