Pharmacoeconomics of antimicrobial therapy

The Effectiveness and Safety of Oral Linezolid for the Primary and Secondary Treatment of Osteomyelitis

The pharmacokinetic profile of oral linezolid makes it an attractive alternative for the treatment of osteomyelitis. Few studies have described the efficacy of linezolid in the treatment of osteomyelitis. A retrospective, observational analysis was conducted at Edward Hines, Jr. VA Hospital. Patients who received oral linezolid from June 2000 to December 2002 were identified from pharmacy records. Forty-two patients who received oral linezolid for osteomyelitis at our institution were identified. Only patients who had received at least six weeks of linezolid therapy were evaluated for clinical effectiveness. Patients were also evaluated for adverse drug reactions due to linezolid. The clinical cure rate was 55% for the 20 patients who received at least six weeks of therapy. Adverse events included gastrointestinal disturbances (15%), thrombocytopenia (10%), anemia (10%), neutropenia (5%) and rash (5%). The authors conclude that oral linezolid is an alterative to intravenous antibiotics for the treatment of osteomyelitis.

General and URTI-specific antibiotic prescription rates in a Malaysian primary care setting

Antibiotic prescribing by primary care doctors has received renewed interest due to the continuing emergence of antibiotic resistance and the attendant cost to healthcare. We examined the antibiotic prescribing rate in relation to selected socio-demographic characteristics of the prescribers at the Seremban Health Clinic, a large public primary care clinic, designated for teaching, in the state of Negeri Sembilan, Malaysia. Data were obtained from: (1) retrospective review of prescriptions for the month of June 2002 and (2) a questionnaire survey of prescribers. A total of 10667 prescriptions were reviewed. The overall antibiotic prescribing rate was 15%; the rate (16%) was higher for the general Outpatient Department (OPD) than the 3% for the Maternal & Child Health Clinic (MCH). The antibiotic prescription rates for upper respiratory tract infection (URTI) were 26% and 16%, respectively, for the OPD and MCH. Half of all the antibiotic prescriptions were for URTI making prescribing for URTI an appropriate target for educational intervention. The URTI-specific antibiotic prescription rate did not correlate with the prescribers' intention to specialise, patient load, perceived patient's expectation for an antibiotic, or the score for knowledge of streptococcal tonsillitis. Prescribing behaviours and record-keeping practices requiring correction were identified.

Erectile response with vardenafil in sildenafil nonresponders: a multicentre, double-blind, 12-week, flexible-dose, placebo-controlled erectile dysfunction clinical trial

OBJECTIVE

To evaluate the efficacy of vardenafil in patients previously unresponsive to sildenafil.

PATIENTS AND METHODS

A multicentre, double-blind, 12-week, flexible-dose, placebo-controlled trial was conducted, involving 463 men aged > or = 18 years with moderate-to-severe erectile dysfunction (ED) and who were unresponsive to sildenafil (by history). After a 4-week treatment-free run-in, patients received placebo or vardenafil 10 mg with the option to maintain current dose or to titrate by one dose level (5, 10 or 20 mg) based on efficacy and tolerability at 4 and 8 weeks. Outcome measures were the erectile function (EF) domain score of the International Index of Erectile Function, two Sexual Encounter Profile diary questions (vaginal penetration and maintenance of erection until successful completion of intercourse), and the Global Assessment Question (GAQ).

RESULTS

There was significantly better EF with vardenafil than with placebo throughout the study. The least-square mean EF domain scores increased from 9.3 at baseline to 17.6 at the 'last' observation carried forward (LOCF) analysis with vardenafil (P < 0.001). Overall least-square mean per-patient success rates more than doubled for penetration (30.3% to 62.3%) and quadrupled for successful intercourse (10.5% to 46.1%) with vardenafil. Improved erections (positive response to the GAQ) were reported by 61.8% of patients receiving vardenafil and 14.7% of those receiving placebo at LOCF (P < 0.001). Normal EF (domain score > or = 26) was achieved by 30% of patients receiving vardenafil and 6% receiving placebo at LOCF (P < 0.001). Adverse events were infrequent and representative of the phosphodiesterase-5 inhibitor profile.

CONCLUSION

Vardenafil is an effective and generally safe treatment for ED, even in men unresponsive to sildenafil (by history).

Evaluation of an antibiotic intravenous to oral sequential therapy program

AIM

This study was designed to analyse the drug consumption difference and economic impact of an antibiotic sequential therapy focused on quinolones.

METHOD

We studied the consumption of quinolones (ofloxacin/levofloxacin and ciprofloxacin) 6 months before and after the implementation of a sequential therapy program in hospitalised patients. It was calculated for each antibiotic, in its oral and intravenous forms, in defined daily dose (DDD/100 stays per day) and economical terms (drug acquisition cost). At the beginning of the program ofloxacin was replaced by levofloxacin and, since their clinical uses are similar, the consumption of both drugs was compared during the period.

RESULTS

In economic terms, the consumption of intravenous quinolones decreased 60% whereas the consumption of oral quinolones increased 66%. In DDD/100 stays per day, intravenous forms consumption decreased 53% and oral forms consumption increased 36%.

CONCLUSIONS

Focusing on quinolones, the implementation of a sequential therapy program based on promoting an early switch from intravenous to oral regimen has proved its capacity to alter the utilisation profile of these antibiotics. The program has permitted the hospital a global saving of 41420 dollars for these drugs during the period of time considered.

IV to Oral Conversion Programs for Anti-Infectives in the United States: Prevalence and Characteristics

Purpose

Despite the documented success of IV to oral anti-infective conversion programs, it is still unclear what the current standard of practice is in the US. A survey was conducted to evaluate the prevalence and characteristics of conversion programs throughout the nation.

Methods

A questionnaire was mailed to 890 randomly chosen hospital pharmacy directors. A preset cutoff date of 4 weeks from the initial mailing was set for responses; a second mailing was sent to those directors that did not respond initially.

Results

A total of 237 (27%) institutions responded. Of these, 74% had instituted conversion programs. More programs required prior physician notification compared with allowing pharmacists to proactively transition candidates (70% vs 30%, P < 0.001). The most common anti-infectives converted were the fluoroquinolones and fluconazole. Common conversion criteria included adequate oral intake and fever reduction. Characteristics associated with an increased likelihood of a conversion program were pharmacy residency programs (RR 1.3; 95% CI 1.132 to 1.477), clinical pharmacists (RR 1.6; 95% CI 1.262 to 2.123), ID specialty pharmacists (RR 1.3; 95% CI 1.153 to 1.499), ID physician consult service (RR 1.2; 95% CI 1.028 to 1.459), and teaching hospitals (RR 1.2; 95% CI 1.038 to 1.386). Hospitals with conversion programs employed a greater number of clinical pharmacists (P = 0.02). Multivariate analysis revealed that the presence of a clinical pharmacist was the most significant variable predicting implementation (P < 0.001).

Conclusion

The majority of hospitals responding to this survey had an intravenous to oral conversion program. While most programs still required prior physician notification, the presence of clinical pharmacists significantly influenced the prevalence of implementation and proactive transition.

Clinical and Economic Analysis of Methicillin-Susceptible and -Resistant Staphylococcus aureus Infections

BACKGROUND:

The rate of methicillin-resistant Staphylococcus aureus (MRSA) has increased significantly over the last decade. Previous cohort studies of patients with MRSA bacteremia have reported higher mortality rates, increased morbidity, longer hospital length of stay (LOS), and higher costs compared with patients with methicillin-susceptible S. aureus (MSSA) bacteremia. The clinical and economic impact of MRSA involving other sites of infection has not been well characterized.

OBJECTIVE:

To determine the clinical and economic implications of MRSA compared with MSSA infections across a variety of infection sites and severity of illnesses.

METHODS:

A retrospective, case—control analysis comparing differences in clinical and economic outcomes of patients with MRSA and MSSA infections was conducted at an academic medical center. Case patients with MRSA infection were matched (1:1 ratio) to control patients with MSSA infection according to age, site of infection, and type of care.

RESULTS:

Thirty-six matched pairs of patients with S. aureus infection were identified. Baseline characteristics of patients with MSSA and MRSA infection were similar. Patients with MRSA infections had a trend toward longer hospital LOS (15.5 vs 11 days; p = 0.05) and longer antibiotic-related LOS (10 vs 7 days; p = 0.003). Median hospital cost associated with treatment of patients with MRSA infections was higher compared with patients with MSSA infections ($16 575 vs $12 862; p = 0.11); however, this difference was not statistically significant. Treatment failure was common in patients with MRSA infection. Among patients with MSSA infections, treatment failure was associated with vancomycin use.

CONCLUSIONS:

Patients with MRSA infections had worse clinical and economic outcomes compared with patients with MSSA infections.

Drug costs and bacterial susceptibility after implementing a single-fluoroquinolone use policy at a university hospital

The University of Kentucky Hospital investigated the feasibility of choosing a sole fluoroquinolone for its formulary in an effort to reduce costs without affecting clinical outcomes. A three-step process was used to plan, implement, and monitor the selection program. Based on the range of clinical indications, safety profile, local susceptibility, cost, and dosing convenience, levofloxacin was chosen over ciprofloxacin and gatifloxacin as the sole fluoroquinolone. Since the implementation of the program in May 2001, susceptibility to levofloxacin has been maintained or increased for the most common pathogens. In addition, University Hospital has saved nearly 100,000 dollars in antibiotic acquisition costs during the first 12 months after the switch. This assessment did not take into account effects in clinical outcomes, such as clinical failures (such as readmission rates), mortality, and adverse events, or measure changes in overall medical expenditures beyond drug acquisition costs. In the future, monitoring of overall patient care and medical care costs, in addition to susceptibility patterns and drug costs, will allow for a better understanding of the long-term benefits of this switch.

Cost analysis of switching from IV vancomycin to PO linezolid for the management of methicillin-resistant Staphylococcus species

BACKGROUND

Infections with methicillin-resistant Staphylococcus species (MRSS) are associated with higher treatment costs than infections with methicillin-sensitive Staphylococcus species in the United States--partly because of an increased length of hospital stay (LOS).

OBJECTIVE

This study used pharmacoeconomic modeling to evaluate the costs and outcomes associated with the use of i.v. vancomycin compared with p.o. linezolid in the treatment of MRSS-infected patients.

METHODS

A retrospective chart review was used to determine the number of cases with confirmed or presumed MRSS infections treated with i.v. vancomycin during calendar-year 2000 at the Veterans Affairs Greater Los Angeles Healthcare System inpatient facility. Patients who were eligible for a switch to p.o. linezolid with or without early discharge to home were identified. Cost differences associated with conversion from i.v. to p.o. therapy (compared with continued i.v. therapy) were estimated based on a mean decreased LOS and a decrease in the costs associated with catheter-related adverse events. Rates and costs of catheter-related adverse events were based on estimates from the literature. Sensitivity analyses were performed by variation of the estimated mean LOS decrease in the SD and by variation of the estimates for incidence and costs related to catheter complications. Costs were measured in year 2000 US dollars, and differences were not assessed for statistical significance.

RESULTS

Of 177 patients treated with i.v. vancomycin, 103 (58%) were eligible for conversion to p.o. linezolid and 55 (31%) were eligible for early discharge from the hospital with continuation of p.o. therapy. Early discharge was associated with a mean (SD) LOS decrease of 3.3 (2.9) days. Annual mean total cost savings in patients eligible for conversion from i.v. vancomycin to p.o. linezolid with early discharge were $294,750 (range, $35,730-$553,790). For cases eligible for inpatient conversion from i.v. vancomycin to p.o. linezolid therapy (n=48), the mean total annual cost difference was an increase of $6340 for p.o. linezolid (range, -$12,910 to $11,900).

CONCLUSION

These results--although partly based on estimates from the literature, rather than direct measurements--support the use of p.o. linezolid with or without early discharge as a potential cost-savings alternative for eligible patients treated with a full course of i.v. vancomycin for suspected or confirmed MRSS infection.

The driving force in hospital formularies: economics versus efficacy

The rising cost of pharmaceuticals has created a focus on hospital cost containment. From 1990 to 2000, spending on prescription drugs increased 200%. Through a variety of mechanisms and contracting, hospital formularies have become increasingly more restrictive. Physician choice with regard to antibiotics specifically is becoming more limited. The field of pharmacoeconomics looks at the cost effectiveness of the drugs we use. The pressures on the pharmaceutical industry and hospitals are reviewed here with a discussion of antibiotic prophylaxis, new expensive therapies, and physician responsibility. The driving force behind hospital formulary design is often economic, whereas the physician desires variety and efficacy. This review discusses some of the key issues related to drug costs and expenditures.

Target site concentrations of ciprofloxacin after single intravenous and oral doses

To characterize the potential of ciprofloxacin penetration into human soft tissues following intravenous (i.v.) and oral (p.o.) administration, we measured the free ciprofloxacin concentrations in interstitial space fluid of skeletal muscle and subcutaneous adipose tissue by microdialysis. In addition, ciprofloxacin concentrations were measured in cantharis-induced skin blisters, saliva, and capillary plasma and were compared to the total concentrations in venous plasma. Furthermore, a pharmacodynamic in vitro model was used to simulate in vivo pharmacokinetics in bacterial culture. Eight healthy volunteers received ciprofloxacin in an open randomized crossover fashion either as a single i.v. infusion of 400 mg over 60 min or as a single p.o. dose of 500 mg. For both tissues the mean areas under the concentration-time curves (AUCs) for interstitial space fluid (AUC(interstitial fluid)s) were significantly lower than the corresponding AUC(plasma)s, with AUC(interstitial fluid)/AUC(plasma) ratios ranging from 0.38 to 0.68. For skeletal muscle, the AUC(interstitial fluid) was significantly higher after administration of 400 mg i.v. than after administration of 500 mg p.o., with a ratio of the AUC after p.o. administration/AUC after i.v. administration of 0.64. The ratio of the concentration in skeletal muscle/concentration in plasma increased over the entire observation period, implying that ciprofloxacin concentrations were not at steady state. The ratio of the concentration in skin blister fluid/concentration in plasma reached values above 4, indicating a preferential penetration of ciprofloxacin into inflamed lesions. The concentrations in saliva and capillary blood were similar to the corresponding total levels in plasma. In vitro both in vivo ciprofloxacin concentration-time profiles were equally effective against select bacterial strains. In conclusion, single-dose administration of two bioequivalent dosage forms of ciprofloxacin might lead to differences in target site pharmacokinetics. These differences, however, are not related to a difference in target site pharmacodynamics.

IV-to-oral switch therapy for community-acquired pneumonia requiring hospitalization: focus on gatifloxacin

The majority of the 1.1 million patients hospitalized for community-acquired pneumonia (CAP) in the United States begin therapy with an intravenous antibiotic. A switch to oral therapy as soon as patients are clinically stable reduces the length of hospitalization and associated costs. Fluoroquinolones are appropriate candidates for switch therapy. Gatifloxacin is an excellent choice when a fluoroquinolone is being considered for sequential switch therapy in the treatment of CAP requiring hospitalization.

Minimized analysis of costs applied to antimicrobial consumption in a rural area

PURPOSE

Antimicrobial agents constitute one of the most utilized groups of drugs in daily clinical practice and, therefore they involve a significant expense. The aim of this study was to evaluate the economic cost of the antimicrobials prescribed in a rural area as well as to search for some cheaper alternatives.

METHODS

Retrospective study. The economic cost of antimicrobial agents prescribed at a health centre over 18 months was studied. To do this, clinical histories of 800 people were reviewed. Afterwards, a minimized analysis of costs was carried out.

RESULTS

The total cost of antimicrobial consumption came to 2,080.752 pts. The average expenditure per patient came to 6,433.85 +/- 14 269.29 pts. Significant differences between the sexes were not found; however, the expenditure in patients of 65 years of age or over was significantly higher than the rest. After applying the ABC analysis it was noticed that macrolides, cephalosporins, antimicrobial combinations and quinolones were the most important groups from an economic point of view. The use of monodose containers would allow us to save up to 7.83% of the total expenditure. In addition, by prescribing the cheapest marketed pharmaceutical product we could save a further 6.54%, and, finally, by combining these two measures the total possible saving would reach 299,052 pts, a 14.37% of the total expenditure.

CONCLUSION

We consider important the elaboration of pharmacoeconomic guides as well as the introduction of monodose containers not only at hospitals but also at community pharmacists.