Influenza outbreak in a long-term-care facility: considerations for pharmacy

Economic evaluation of oseltamivir phosphate for postexposure prophylaxis of influenza in long-term care facilities

OBJECTIVES

To compare the cost-effectiveness of oseltamivir postexposure prophylaxis during influenza A outbreaks with that of amantadine postexposure prophylaxis or no postexposure prophylaxis in long-term care facilities (LTCFs).

DESIGN

Cost-effectiveness analysis based on decision analytic model from a government-payer perspective.

SETTING

A Canadian LTCF, with high staff vaccination, at the beginning of influenza season.

PARTICIPANTS

Elderly, influenza-vaccinated patients living in a Canadian LTCF.

MEASUREMENTS

Incremental costs (or savings) per influenza-like illness case avoided compared with usual care.

RESULTS

From a government-payer perspective, this analysis showed that oseltamivir was a dominant strategy because it was associated with the fewest influenza-like illness cases, with cost savings of $1,249 per 100 patients in 2001 Canadian dollars compared with amantadine and $3,357 per 100 patients compared with no prophylaxis. Costs for amantadine dose calculation and hospitalization for adverse events contributed to amantadine being a more-expensive prophylaxis strategy than oseltamivir. Both prophylaxis strategies were more cost-effective than no prophylaxis.

CONCLUSION

Despite high influenza vaccination rates, influenza outbreaks continue to emerge in LTCFs, necessitating cost-effective measures to further limit the spread of influenza and related complications. Although amantadine has a lower acquisition cost than oseltamivir, it is associated with more adverse events, lower efficacy, and individualized dosing requirements, leading to higher overall costs and more influenza-like illness cases than oseltamivir. Therefore the use of oseltamivir postexposure prophylaxis is more cost-effective than the current standard of care with amantadine prophylaxis or no prophylaxis.

Influenza prophylaxis in the long-term care facility: a case-control study of the risk factors for adverse drug reactions to amantadine

BACKGROUND

Amantadine hydrochloride remains an inexpensive means of influenza A prophylaxis, but it is reported to have a high incidence of adverse drug reactions (ADRs) in residents of long-term care facilities (LTCFs) compared with newer, more expensive drugs.

OBJECTIVE

This study attempted to determine the effects of poor renal function on the rate of ADRs and any other variables on the tolerability of prophylaxis in this population. This would allow a high-risk subset of LTCF residents to be identified before prophylaxis, thus decreasing the risk for ADRs from amantadine.

METHODS

In this retrospective case-control study, a course of standardized low-dose (100-mg/d tablets) amantadine prophylaxis was ordered for all 242 residents of Ten Broeck Commons LTCF in Lake Katrine, New York, without influenza A for 14 days. Chart data of residents who developed ADRs (ADR group) were compared with those of a selected group who did not (control group). Residents' age, sex, renal function (blood urea nitrogen, serum creatinine, and creatinine clearance), dementia diagnosis, and number and classes of medications were compared.

RESULTS

The ADR group comprised 25 residents (21 women, 4 men; mean [SD] age, 84.8 [8.4] years); the control group, 29 residents (23 women, 6 men; mean [SD] age, 85.7 [7.5] years). The development of ADRs was not associated with differences in age, sex, renal function, or any medical condition, including measured, preexisting mental status changes between the groups. The overall risk for ADRs in the 242 residents was highest between days 8 and 14 of prophylaxis (17 residents [7.0%]) compared with the first 7 days (8 residents [3.3%]). Acute confusion was the most common ADR. All ADRs resolved on cessation of treatment.

CONCLUSIONS

No preexisting medical condition was statistically associated with an increased risk for ADRs, but an association with the number of days of prophylaxis was observed. By shortening prophylaxis to 7 days, the ADR risk may be lowered to be commensurate with more expensive medications.

Nosocomial influenza in children

Influenza is the most important cause of acute respiratory illness leading to hospitalization among children during community epidemics. This illness can cause extensive nosocomial outbreaks with serious morbidity and mortality among specific groups of children. Paediatric patients with community-acquired influenza and healthcare workers are the main reservoir for the nosocomial spread of the virus. During epidemics in the community, testing for influenza should be requested in all children with compatible symptoms admitted in the hospital, and measures should be introduced for the prevention or early control of an outbreak. Recent advances in the management of influenza include rapid diagnoses based on antigen detection and the identification of the new neuraminidase inhibitors zanamivir and oseltamivir. Annual vaccination against influenza of children with high-risk conditions, their family members and healthcare workers is the principle measure for the prevention of nosocomial outbreaks. Although vaccination against influenza appears to be cost-effective at all ages in terms of prevention of illness, related hospitalizations, deaths, reduction of healthcare costs and productivity loss, vaccination coverage among target groups is limited.

Use of oseltamivir during influenza outbreaks in Ontario nursing homes, 1999-2000

OBJECTIVES

To describe the experience of Ontario long-term care facilities that used oseltamivir during influenza outbreaks in 1999/2000.

DESIGN

Case series.

SETTING

Ten Ontario long-term care facilities for older people and their residents.

PARTICIPANTS

Older residents of long-term care facilities.

INTERVENTION

Oseltamivir for treatment or prophylaxis during 11 influenza outbreaks in 1999/2000.

MEASUREMENTS

Control of outbreaks; pneumonia, hospitalization, and death complicating acute influenza.

RESULTS

All outbreaks were due to influenza A//H3N2/Sydney/05/97. One facility elected to use oseltamivir for treatment and amantadine for prophylaxis. The remaining nine facilities (10 outbreaks) recommended oseltamivir for treatment and prophylaxis (after amantadine failure in five and as primary prophylaxis in five). Use of oseltamivir was associated with termination of the outbreak in all eight evaluable outbreaks. Overall, 178/185 (96%) case-residents met the case definition of influenza and had complete data for evaluation. Of these, 63 (35%) were treated with antibiotics, 37 (21%) were diagnosed with pneumonia, 19 (11%) were hospitalized, and 16 (9%) died. Compared with residents receiving no therapy or who became ill while taking amantadine, residents who received oseltamivir within 48 hours of the onset of symptoms were less likely to be prescribed antibiotics, to be hospitalized, or to die (P <.05 for each outcome). These differences persisted and remained statistically significant when corrected for influenza immunization status. A total of 730 residents received oseltamivir prophylaxis for a median of 9 days (range 5-12). Of these, side effects were identified in 30 (4.1%), the most common being diarrhea (12 residents, 1.6%), cough (5, 0.7%), confusion (4, 0.5%) and nausea (4, 0.5%).

CONCLUSIONS

Oseltamivir is safe and appears to be effective when used as treatment or prophylaxis to control outbreaks of influenza in older nursing home residents.