Patients with multiple myeloma (MM) who receive proteasome inhibitors (PIs) are at an increased risk for herpes zoster infection, and National Comprehensive Cancer Network guidelines recommend antiviral prophylaxis for these patients. Researchers examined the use of and adherence to antiviral agents in this patient population. Siyang Leng, MD, at Columbia University Medical Center in Sunnyside, New York, discussed the findings at the ASH Annual Meeting.

Using the Truven MarketScan Database, researchers performed a retrospective cohort analysis, identifying 6,934 patients with MM continuously receiving PIs (bortezomib or carfilzomib) for at least three months between January 2009 and December 2013. They identified pharmacy claims for one or more prescriptions of acyclovir and valacyclovir to identify those receiving herpes zoster prophylaxis.

The researchers defined adherence as having a medication possession ratio (the sum of all days supplied by the pharmacy divided by the number of days between the first and last prescription) of 80% or higher over three months in patients who filled at least two prescriptions for an antiviral agent. Researchers also assessed factors related to age, calendar year, geographic location, living in a metropolitan area, employment status, health plan, type of pharmacy, prior herpes infection, antiviral use prior to initiation of PI, and Charlson Comorbidity Index score.

A total of 3,632 patients (52%) filled a prescription for an antiviral agent at least once during the follow-up period. Acyclovir was more commonly used than valacyclovir (74% versus 26%).

Factors associated with antiviral use included:

  • More recent calendar year (odds ratio [OR] = 2.27 for 2013 versus 2009, 95% CI = 1.91–2.71)
  • More concurrent chemotherapy agents (OR = 1.82 for three versus one agent, 95% CI = 1.56–2.12)

Among patients who received an antiviral agent more than once (n = 2,803), adherence to herpes zoster prophylaxis was 84% during the course of three months.

Factors associated with adherence included:

  • Those who were retired (OR = 1.70, 95% CI = 1.20–2.42)
  • Those using mail order pharmacies (OR = 2.22, 95% CI = 1.19–4.61).

Patients receiving antiviral agents were less likely to develop herpes zoster (hazard ratio = 0.40, 95% CI = 0.30–0.52).

“Although use of antiviral therapy was associated with a decreased risk of herpes infections, we found that half of patients [with MM] in the United States did not receive this guideline-recommended care,” the researchers concluded. “More efforts are needed to prevent this important complication in patients [with MM] on PIs.”

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