Appropriate Usage of Oseltamivir during 2009 H1N1 Pandemic

Background: The current 2009 H1N1 pandemic has few medication treatment options. The most common treatment has been oseltamivir. With the recent outbreaks in 2009, prescriptions for oseltamivir increased dramatically, sparking concern about the proper usage and available supply. The CDC and other major organizations have issued guidelines regarding indications for proper use of oseltamivir, including reservation of the medication for patients who are at high risk for complications, and who have had symptoms for less than 48 hours.

Objective: The objectives of this study are to determine how often oseltamivir is prescribed within these guidelines, and to formulate strategies to ensure appropriate prescribing to patients most likely to benefit, and to preserve available supplies in the event of larger future outbreaks.

Methods: Using the electronic medical record database at our staff model HMO, we evaluated all 783 charts for patients who received oseltamivir over the 6 month period from April through September 2009. Data was analyzed with regard to patient demographics and indication, including presenting symptoms (fever, cough, myalgia, and sore throat), onset of symptoms, co-morbidities, and whether use was for prophylaxis or active treatment.

Results: 1.   10% (75/783) of patients had no documentation of indication for oseltamivir in their health record.  Some of these prescriptions may have been for personal stockpiling or diversion.
2.   17% (106/627) of patients were prescribed oseltamivir for active treatment with symptom onset documented >72 hours, beyond the time frame for expected effectiveness for outpatients.
3.   17% (105/627) of patients were prescribed oseltamivir for active treatment with symptom onset documented between 48 to 72 hours, borderline for possible effectiveness in outpatients.
4.   29% (20/70) of patients prescribed oseltamivir for prophylaxis had no documentation of household contact exposure; either no exposure history was indicated or exposure was casual in nature.

Conclusions: In the majority of cases, prescribers followed CDC guidelines. However, in a significant minority of cases, oseltamivir may have been prescribed inappropriately. As a direct result of the above findings, these educational efforts were directed at prescribers:
1. Oseltamivir is unlikely to be of significant benefit in outpatients with onset of symptoms >72 hours.
2. Benefit from oseltamivir may be limited in outpatients with mild symptoms with onset >48 but ≤72 hours.
3. Prophylactic treatment is recommended only in high risk patients with a household contact exposure.

 

Spot follow up checks are planned to ensure that prescribers remain within guidelines when appropriate.  In addition, our entire service area (480,000 lives) now mandates all oseltamivir prescriptions have an accompanying patient record entry documenting indication. This requirement may discourage diversion of potentially limited supplies.