Trends of Oseltamivir Usage in the United States during the 2009 Influenza A (H1N1) Pandemic CDR John K. Iskander LCDR Craig Hales Charbel el-Bcheraoui Robert T. Chen Centers for Disease Control and Prevention

Detection of Novel H1N1 Virus March cases of febrile respiratory illness in children (un-related, no pig contact) Residents of adjacent counties in southern California, ill in late March Novel swine influenza A (H1N1) virus detected at CDC on April 15 th,17th Both viruses genetically identical Contain a unique combination of gene segments previously not recognized among swine or human influenza viruses in the United States Retrospective evidence of respiratory illness outbreaks in Mexico (February/March) April 26, 2009 US declares National Public Health Emergency June 11, 2009 WHO declares Global pandemic of novel influenza A (H1N1) virus

Pandemic H1N1: Disease burden estimates In United States, as of 3/13/2010: –59.98 million cases –270, 435 hospitalizations –12, 271 deaths Mean age of deaths 37 years –Source: CDC website

Influenza Antivirals: Background Treatment of suspected or confirmed influenza with antiviral medications is one important strategy to reduce morbidity and mortality caused by the 2009 pandemic influenza A (H1N1) virus (pH1N1) The pandemic strain has been susceptible to neuraminidase inhibitors (NAI) such as oseltamivir (> 99% of isolates) NAI (oseltamivir, zanamivir) antiviral treatment is recommended* as soon as possible for: All hospitalized patients with suspected, probable, or confirmed 2009 influenza A (H1N1) virus infection Outpatients with high-risk conditions (including children < 2 years old, pregnant women and women up to 2 weeks post-pregnancy, persons ages 65 and older, persons with chronic conditions - chronic lung disease, diabetes, etc.) with suspected, probable, or confirmed 2009 influenza A (H1N1) virus infection * Current CDC Antiviral Treatment Recommendations for pH1N1 influenza

Objectives To monitor the usage of influenza antivirals by pH1N1 age-specific risk groups, and to assess related geographic and time trends in the United States To evaluate effectiveness of CDC guidance on use of antiviral medicines

Monitoring of Influenza Antiviral Medication Usage Through BioSense*, CDC receives anti-infective prescription data from 27,000 pharmacies, representing approximately half of U.S. anti- infective prescription data – Data include patient demographics (age and sex) and pharmacy zip code *For more information see

System Description BioSense receives prescription data from an electronic prescriptions claims provider in all 50 states and Washington, D.C. as well as U.S. territories. Data are updated every 4 hours The data collected concern all prescriptions for anti-infective medicines and include the specific type (brand) and formulation dispensed These data cover about 50% of all anti-infective medicines prescribed in the states and represent prescriptions requested at retail pharmacies and approved to be covered by insurance companies – Coverage range for prescription transactions for the 9 census divisions: mean 49.7%, range %

Pharmacies — 27,000 Active

Methods Rates of antiviral medication prescribing are calculated using population data from the U.S. Census, and are compared with national and regional measures of influenza disease activity – % of visits for influenza-like illness (ILI) assessed through U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) We analyzed oseltamivir (Tamiflu®) prescribing data by age groups and federal regions from April through December 2009

Results

Nationwide rates of Rx of Oseltamivir by age groups, USA,

Nationwide rates of Oseltamivir prescribing by age groups USA, April-December 2009

DHHS Regions I-X

Regional rates of Rx of Oseltamivir by age groups, Federal Region 4, April-December 2009

Regional rates of Rx of Oseltamivir by age groups, Federal Region 9, April-December 2009

Summary of Results of Monitoring Nationally, highest rates of prescribing were seen shortly after detection of the pandemic in spring of 2009, as well as in September-October of 2009 – Two distinct peaks seen in autumn of 2009 Children (infants, pre-school age, and school age) were prescribed the medication at the highest rates Medication prescribing for all ages has sharply decreased since November 2009

Results Details School-age children (5-18 years) consistently had the highest prescribing rates, with a peak of > 500 prescriptions/100,000 population during September 2009 Pre-school age children (2-4) had similar prescribing rates, reaching 450/100,000 in both September and October Patterns of prescribing for infants generally paralleled those seen for older children but with lower peak rates (350/100,000) After the initial May peak, prescribing rates for working age adults (18-64) and the elderly (65 and over) were < 200 courses/100,000 Regional prescribing patterns clustered geographically, with prescribing rates in contiguous regions increasing and decreasing synchronously

Interpretation of findings Prescribing rates have been highest overall among pediatric age groups, who are at high risk of H1N1 illness Lower rates of prescribing for those 65 and over are consistent with low rates of H1N1 disease in this age group Rates of prescribing were closely related to levels of influenza disease activity, both nationally and regionally Despite widespread prescribing of oseltamivir, so far no detection of significant levels of viral resistance or new safety concerns

Strengths and Limitations Strengths – Data updated frequently – Significant population coverage – Ability to generate age adjusted prescribing rates – Exploring ability to provide data linked to claims Limitations – Ecologic analysis; no linkage to patient level diagnostic information – No data from hospital pharmacies – No coverage for self-pay or those with no prescription insurance coverage

Conclusions Prescribing rates were highest overall among pediatric age groups, who are at high risk of H1N1 illness Rates of prescribing were closely related to levels of influenza disease activity, both nationally and regionally

Future (and Present) Uses of Pharmacy and other Drug Utilization Data Monitoring of both infectious and chronic diseases Use as denominator data for pharmaceutical safety/adverse event monitoring Use by Strategic National Stockpile (SNS) to monitor formulation shortages and adjust stockpile distribution

Antiviral Adverse Event Monitoring – Comparison by Season* December 31, 2009 *Note: AE data lagtime is 2-3 weeks.

*Up-to-date through 12/31/09 (DAWN) and 12/26/09 (BioSense). Note: AE data lagtime is 2-3 weeks. Antiviral AE Monitoring and Antiviral Dispensing, December 31, 2009

Acknowledgments Taha Kass-Hout and BioSense staff CAPT Anthony Fiore, Influenza Division, CDC CDR Dan Budnitz, Division of Healthcare Quality Promotion, CDC

Supplemental

Background on BioSense BioSense is a national program intended to improve the nation’s capabilities for conducting real-time biosurveillance, and enabling health situational awareness through access to existing data from healthcare organizations across the country BioSense receives, analyzes, and evaluates health data from numerous data sources such as emergency rooms, ambulatory care clinics, and clinical laboratories For more information: – –

Location of BioSense Pharmacies (N≈27,000)

Antiviral AE Monitoring and Antiviral Dispensing, December 31, 2009