Comparative effectiveness of low-molecular-weight heparins after therapeutic interchange

Systematic literature review of the methodology for developing pharmacotherapeutic interchange guidelines and their implementation in hospitals and ambulatory care settings

PURPOSE

To summarize literature specific to therapeutic interchange (TI) focusing on methodological approaches in order to develop a list of steps that healthcare facilities can consult when developing pharmacotherapeutic interchange guidelines (PTIGs) in hospitals and primary care centers.

METHODS

A search was conducted in PreMEDLINE, Medline, EMBASE, PsycINFO, and the Cochrane Library up to and including December 2015. PRISMA guidelines were used. The inclusion criteria were articles published on TI: methodology, implementation, guidelines, and position statements of scientific societies. Two authors independently reviewed all articles for eligibility and extracted the data.

RESULTS

A total of 102 articles were selected for full-text review; we included three guidelines on how to effect TI, nine position papers of various scientific societies with regard to TI, two articles dealt exclusively about methodology, three articles consisted of recommendations and perspectives on TI, three articles dealt with legal aspects, four articles examined general implementation procedures, two articles were a post-discharge follow-up of patients who had TI, six were surveys referring to TI, and three were articles on the use of TI in ambulatory care The remaining 67 articles focused on therapeutic groups. Study quality was generally low.

CONCLUSIONS

This review identified articles on TI as published guidelines, recommendations, and studies on TI carried out in hospital settings. As a result, eight fundamental steps were established for obtaining adequate results in the development of TI programs.

Pharmacologic and Liability Considerations of Therapeutic Interchange with Low-Molecular-Weight Heparins

Therapeutic interchange (TI), a formulary management process, is used by health care systems to help contain medication costs. A scientifically defensible and pharmacoeconomically beneficial TI program adheres to rigorous criteria enforced by an institution's Pharmacy and Therapeutics Committee. In situations where adherence to essential criteria is not mandated, TI may not produce the intended clinical and economic outcomes, and in practice may have legal implications. Appropriate application of TI has been described within the position statements of certain health care organizations and associations. Due to the high cost and frequent use of low-molecular-weight heparins (LMWHs), health care institutions have identified this pharmacologic class as a potential target for TI. Currently, the application of the TI process to LMWHs is questionable. This paper reviews the TI process and explores its controversial role in the formulary management of LMWHs.

Low-Molecular-Weight Heparin Therapy for Patients Undergoing Total Knee Replacement Surgery: Cost and Outcomes

Objective:

In March 1997, a community hospital system changed the low-molecular-weight heparin (LMWH) product on formulary from enoxaparin to dalteparin through a therapeutic interchange for all uses except patients undergoing total knee replacement (TKR) surgery. In October 1997, therapeutic interchange of LMWHs (enoxaparin to dalteparin) was instituted for patients undergoing TKR surgery. The cost equivalence of these therapies in TKR surgery was evaluated.

Methods:

A cohort of patients admitted to three health-system facilities who underwent primary TKR surgery between July 1, 1996 and December 31, 1998 was assembled retrospectively. Costs and outcomes associated with a formulary interchange for LMWH products (from enoxaparin to dalteparin) initiated in October 1997 for TKR surgery were analyzed using data abstracted hospital records and decision support systems. To evaluate equivalence between the drugs, the difference in median inpatient health care costs (with 95% confidence intervals [CIs]) was calculated. Equivalence of outcomes (eg, adverse events) in terms of risk ratios was also evaluated.

Results:

Inpatient costs were essentially equivalent for patients treated with enoxaparin (n = 88) and dalteparin (n = 101), with a slightly higher median cost among enoxaparin-treated patients ($172 [95% CI, -$17 to + $395]). CIs for the crude and regression-adjusted findings included the possibility of no cost difference (ie, $0). The median time to hospital discharge was identical, at 6 days. Outcomes were otherwise similar between the two groups.

Conclusions:

Our therapeutic interchange program was successful. Inpatient costs were equivalent when patients were treated with either enoxaparin or dalteparin for TKR surgery.

Therapeutic Interchange of Parenteral Anticoagulants: Challenges for Pharmacy and Therapeutics Committees

This is a review of key factors for pharmacy and therapeutics committees to consider when developing a therapeutic interchange (TI) program for venous thromboembolism (VTE) prophylaxis. Recent patient safety initiatives aimed at reducing the incidence of hospital-acquired VTE may increase the prescribing of thromboprophylactic agents recommended in VTE management guidelines. As a result, more pharmacy and therapeutics committees may consider TI programs for parenteral anticoagulants. However, the TI of anticoagulants appears challenging at this time. Firstly, the therapeutic equivalence of the commonly prescribed parenteral anticoagulants, enoxaparin, dalteparin and fondaparinux, has not been established. Secondly, because of the wide range of clinical indications for these anticoagulants, a blanket agent-specific TI program could lead to off-label use. Use of an indication-specific TI program could be difficult to manage administratively, and may cause prescribing confusion and errors. Thirdly, careful dosing and contraindications of certain parenteral anticoagulants in special patient populations, such as those with renal impairment, further impact the suitability of these agents for inclusion in TI programs. Finally, although TI may appear to offer lower drug-acquisition costs, it is important to determine its effect on all cost parameters and ultimately ensure that the care of patients requiring VTE prophylaxis is not compromised.

Factors that influence prescribing within a therapeutic drug class

RATIONALE, AIMS AND OBJECTIVES

The decision to prescribe one drug instead of another within the same therapeutic class may be influenced by a variety of drug-related, direct, or indirect factors; but little is known about which considerations are most important in such choices. The low-molecular-weight heparins (LMWHs) represent a class of drugs that are commonly used and for which therapeutic equivalence has been debated in the literature. The purpose of this study was to identify and compare factors perceived by doctors and clinical pharmacists to be influential in prescribing decisions among LMWHs.

METHODS

Doctors and clinical pharmacists were interviewed to elicit information and to rank factors that influence the prescribing and use of LMWHs in community hospitals in the United States. For each factor, the mean and median of the rating were determined along with the frequency distribution across ratings. The non-parametric Mann-Whitney U-test was used to examine differences between doctors and clinical pharmacists.

RESULTS

Both groups considered efficacy, formulary status, and policies restricting drug use to be highly influential in the decision to use one LMWH instead of another. Compared to clinical pharmacists, doctors rated personal experience as more influential, whereas they rated drug cost and prescribing guidelines lower.

CONCLUSIONS

These findings suggest that doctors and clinical pharmacists differentiate between LMWHs based on differences between products and because of hospital administrative programs (such as drug formularies). This information may be of value in designing programs to alter medication use.

Hospital guidelines for use of low-molecular-weight heparins

OBJECTIVE

To describe the development of guidelines for initial use of low-molecular-weight heparins (LMWHs) and other anticoagulants in acute-care hospitals that are part of a national group purchasing organization (GPO).

DATA SOURCES

A systematic literature search (1970-December 2001) was conducted to identify evidence on the efficacy of various anticoagulants for initial therapy in deep-vein thrombosis and pulmonary embolism, and in treatment of acute coronary syndrome. A group consensus method was then used to develop guidelines. Guidelines were reviewed and revised by an internal expert panel as well as an external expert panel. Final guidelines were disseminated to GPO members and assistance was provided with implementation at the local level.

RESULTS

The final set of guidelines is described. The guidelines are organized based on recommended therapeutic options for each indication. For each option, consensus opinion is provided on the level of evidence that exists in the literature, comparisons of cost and convenience, and additional dosing information. The guidelines were disseminated along with supporting material to interested GPO member hospitals, and teleconferences were held to facilitate implementation at the local level. The guidelines were initially implemented at 18 hospitals across the country.

CONCLUSIONS

The process by which these guidelines were developed, plus the final set of guidelines, may be useful to hospitals and healthcare systems contemplating or engaged in a similar effort with this class of drugs.

Utilisation and safety of low molecular weight heparins: prospective observational study in medical inpatients

AIMS

Low molecular weight heparins (LMWHs) are widely used as curative or preventive treatments of thromboembolic diseases. The aim of our study was to: investigate the pattern of prescription of LMWHs in different departments of French teaching hospitals; andestimate the incidence of adverse drug reactions (ADRs) induced by LMWHs and associated risk factors for the occurrence of bleeding events.

METHODS

This prospective study was performed in two teaching hospitals in Toulouse (south-western France) in March 1999 in different medical wards. All patients receiving a prescription for a LMWH were included in the survey. All data were prospectively recorded in each ward.

RESULTS

A total of 334 patients were included. Sex ratio (male/female) was 1.25 and mean age was 72.5 +/- 16.3 years (extremes:18-101). 450 prescriptions for LMWHs were collected (1.34 prescription per patient) and involved mainly enoxaparin (61%), which was more frequently used than tinzaparin in patients over 75 years old (71.7 vs 28.3%; p < 0.0001). Ninety-nine patients received a LMWH for curative treatment (corresponding to 127 prescriptions of which 99 were for enoxaparin and 28 were for tinzaparin [p < 0.0001]). Indications included therapy for deep venous thrombosis, pulmonary embolism, acute coronary syndrome, unstable angina pectoris, non-Q-wave myocardial infarction. Serious renal insufficiency was significantly more frequent in patients from the geriatrics department (p < 0.00001). Enoxaparin was prescribed more frequently in patients with serious or moderate renal insufficiency than tinzaparin (72 vs 61%, p < 0.05). The incidence of LMWHs-induced ADRs was 10.5% occurring in 22 cases during preventive treatment of deep venous thrombosis and in 13 cases during curative therapy. ADRs were classified as 'serious' in 11 cases (31.4%). Reported ADRs were bleeding events (n = 15), thrombocytosis (n = 13), thrombopenia (n = 4) and hepatic cytolysis (n = 1). The mean delay for the occurrence of bleeding effects was 8.0 +/- 9.1 days (range 1-40). Multivariate analysis of the influence of several criteria on the occurrence of haemorrhagic effects showed that the decrease of creatinine clearance (10 ml/min) was associated with an increased haemorrhagic risk (relative risk [RR] = 1.34, 95% CI 1.12-1.65; p < 0.05). Moreover, the risk of adverse bleeding effects increased for patients with a creatinine clearance <20 ml/min (RR = 2.8; 95% CI 1.00-7.8).

CONCLUSION

Our data firstly show a different pattern of LMWHs prescription in different clinical wards. Secondly, the risk of bleeding ADRs in patients treated by LMWHs increases significantly with renal function impairment for the two LMWH preparations studied. More pharmacoepidemiological studies are necessary in patients with several risk factors, particularly in elderly people who often have renal impairment, in order to determine the optimal pattern use of each LMWH.

Lack of therapeutic interchangeability of HMG-CoA reductase inhibitors

OBJECTIVE

To review relevant literature and provide an opinion on the class effect of hydroxymethylglutaryl coenzyme A reductase inhibitors (statins).

DATA SOURCES

Primary and review articles were identified by MEDLINE search (1990-July 2002).

STUDY SELECTION AND DATA EXTRACTION

Editorials, studies, and review articles related to the class effect or therapeutic interchangeability of statins were reviewed. Also included was information that is relevant to this topic.

DATA SYNTHESIS

Although statins share common main actions, they may have clinically important differences in terms of efficacy and safety. At fixed or allowable dosages, rosuvastatin, atorvastatin, and simvastatin produced greater low-density lipoprotein cholesterol-lowering effects compared with other statins. Some statins have shown reduction in either cardiovascular and/or total mortality. Statins also differ in their structure, pharmacokinetics, potency, and rate of metabolism, any or all of which may have clinical significance. Although inconclusive, subtle differences in nonlipid effects of some statins may have contributed to positive benefits observed in clinical studies. As a result of drug-related deaths, cerivastatin was withdrawn voluntarily from the market, which may raise the question whether there is therapeutic interchangeability (due to class effect) among statins.

CONCLUSIONS

Despite the competition for market share and strategies attempting to identify differences in therapeutic value, few head-to-head comparisons between statins have been performed. The limited, available data suggest that statins are not therapeutically interchangeable.

Anticoagulation therapy

Despite refinements and standardization in the use of anticoagulants, many problems remain for clinicians. Dr. Crowther describes appropriate starting and maintenance doses of warfarin, factors accounting for inter- and intra-observer variability and importantly, the management of the over-anticoagulated patients and bleeding patients. Dr. White compares unfractionated heparin (UFH) and low molecular weight heparin (LMWH) and addresses whether there truly are differences in the efficacy and safety of different LMWH's for both arterial and venous indications. Dr. Ortel discusses the management of the problem patient who requires anticoagulants, the management of heparin-induced thrombocytopenia, the pregnant patient, the obese patient, patients who have renal insufficiency and/or liver disease, patients with malignant disease, and other challenging patient populations.

Applying scientific criteria to therapeutic interchange: a balanced analysis of low-molecular-weight heparins

Under pressure to provide cost-effective healthcare, many healthcare systems have adopted Therapeutic Interchange (TI) programs-the interchange of therapeutically equivalent but chemically unique drugs-to reduce the total cost of therapy without compromising patient care. To be appropriate and feasible, a TI program for any class of drugs must meet certain rigorous criteria and undergo medical, financial, tactical, and legal reviews. Moreover, once a TI program is implemented, a process to monitor its success should be established. Application of the TI criteria to low-molecular-weight heparins (LMWHs) reveals that a blanket TI program for LMWHs does not appear advisable at this time.