A Linezolid Prior Authorization Program: Clinical and Economic Outcomes

This study demonstrated that a linezolid PA program did not appear to be associated with a negative impact on medical outcomes and was associated with lower costs.
Published Online: April 16, 2014
Catherine I. Starner, PharmD, BCPS; R. Scott McClelland, PharmD; Yang Qiu, MS; Richard A. Zabinski, PharmD; Nancy Cotter, PharmD; and Patrick P. Gleason, PharmD, BCPS, FCCP
Objectives: Given the criticism of prior authorization (PA) programs for being barriers to medication access and causing increased healthcare consumption and costs, we sought to assess the impact of a linezolid PA program on utilization, total cost of care, and hospitalization/emergency department (ED) visits.

Study Design: Quasi-experimental design with intervention group compared with a concurrent comparison group.

Methods: Pharmacy claims among 1.2 million commercially insured members exposed to a linezolid PA were queried for rejected linezolid claims between January and June, 2011. A comparison group without a PA was identified from 1.1 million members with paid linezolid claims. Outcomes assessed during 30-day follow-up and 60-day sensitivity analysis: antibiotic claims, hospitalizations, ED visits, outpatient visits, and total medical and pharmacy costs. A logistic regression model tested hospitalizations/ED visit differences, with adjustment for covariates. Cost analyses were performed using the generalized linear model with Gamma distribution and adjusted for covariates.

Results: A total of 28 (15.1%) of 185 intervention group members had no antibiotic claims in the 30-day follow-up. Mean per member adjusted overall total costs of care were $5868 lower in the intervention group (P = .012). The logistic regression model found no difference in hospitalizations/ED visits (P = .661). The intervention group had 37% lower pharmacy costs (relative cost [RC] 0.63, P = .016) and 38% lower total cost of care (RC 0.62, P = .012) than the comparison group. Results were maintained during a 60-day sensitivity analysis.

Conclusions: The linezolid PA program evaluated does not appear to be associated with a negative impact on medical outcomes, and was associated with lower costs.

Am J Pharm Benefits. 2014;6(2):81-88
Clinical programs aimed at appropriate use of drugs will remain a primary function of health insurers in the future and the findings of this study demonstrated a significant savings associated with a linezolid prior authorization (PA) program along with no difference in clinical outcomes among members who were or were not exposed to the linezolid PA program. 
  • A health plan or pharmacy benefit manager can influence appropriate linezolid use through implementation of a PA program. 

  • These results demonstrate that such a program aimed at the antibiotic linezolid could be applied without concern for an increase in negative clinical consequences. 

  • The intervention group appreciated a $0.024 per member per month antibiotic savings over a 30-day follow-up period, with both clinical and economic findings maintained at 60 days.
As pharmacy benefit costs continue to rise, health insurers and plan sponsors are increasingly implementing utilization management programs across a broad array of drugs and drug classes.1 The Academy of Managed Care Pharmacy defines utilization management as2:

“…managing the use of medical services to ensure that a patient receives necessary, appropriate, highquality care in a cost-effective manner. As it applies to a pharmacy benefit, utilization management is any of a number of measures used to ensure appropriate medication utilization. Such measures may include quantity limitations, step-therapy, prior authorization, and/or additional steps as deemed appropriate by the health plan’s Pharmacy and Therapeutics (P&T) Committee.”

Utilization management programs have been a mainstay of managed care pharmacy clinical programs for over 20 years, with prior authorization (PA) being the most common.3,4 A 2013 survey conducted by the Pharmacy Benefit Management Institute reported that 86% of 424 employers use PA as one of their utilization management tools, a 10% increase from the prior year.1 However, PA programs have been criticized for being time consuming and a potential barrier to medication access. Although little research has been done to evaluate these criticisms, there is concern that PA programs may lead to increased healthcare resource consumption and costs.5,6

One reason for prescription abandonment is high out-of-pocket (OOP) member cost shares.7 A linezolid claim could be more than $2000, and often carries high member cost share; as such, studies on linezolid have primarily focused on the economic outcomes following a reversed claim. A reversed claim generally indicates that a prescription was received by a pharmacy but never dispensed to the member. A 2010 retrospective analysis of Medicare Advantage claims evaluated the incidence of linezolid claim reversals in patients recently discharged from the hospital. In the 60-day period following the linezolid reversal, investigators found that 34.9% of patients did not receive any antibiotics and that there were signifi cantly higher medical costs among those with a reversed claim for linezolid. When costs among members with paid (non-reversed) linezolid claims were compared with those with reversed claims, the group with paid linezolid claims had higher drug costs offsetting their lower medical costs, making total cost of care no different between groups.8 Another Medicare study found similar results: higher total medical costs were associated with linezolid claim reversals, and the reversals were more common among members with a high cost share. In addition, members with a reversed linezolid claim also experienced higher rates of rehospitalization.9 These study findings may discourage development of programs aimed at linezolid or antibiotics in general.

Linezolid, a synthetic oxazolidinone antibiotic, was approved by the US Food and Drug Administration (FDA) in 2000 for the treatment of bacterial pneumonia, skin and skin structure infections, and vancomycinresistant enterococcal (VRE) infections.10 While linezolid is considered a broad spectrum Gram-positive antibiotic with low resistance rates, widespread use is not without risk. Reportedly, up to 50% of all antibiotic use is unnecessary and can contribute to antibiotic resistance.11,12 Also, antibiotic prescribing trends differ regionally across the United States, with southern states showing rates of 936 per 1000 persons compared with 639 per 1000 persons in the western states.11 In 2007, the FDA issued a safety alert after results from a study evaluating linezolid use in catheter-related infections demonstrated higher mortality in patients treated with linezolid (21.5% vs 16.0%).13 Furthermore, linezolid has been associated with serious central nervous system reactions when administered with commonly prescribed serotonergic medications (eg, SSRI antidepressants).14,15

Antibiotic resistance is a global problem. The gaps in our knowledge about resistance are due to limited capacities to detect and respond to emerging antibiotic resistance threats.16 VRE infections are considered a serious threat by the Centers for Disease Control and Prevention.16 Appropriate use of linezolid is paramount, considering the potential for antibacterial resistance and safety concerns. The objective of this study was to evaluate the economic and clinical outcomes of a linezolid appropriate-use PA program in commercially insured members compared with a concurrent comparison group who were not exposed to the program.


The study compared an intervention group with a comparison group using a quasi-experimental concurrent design. The intervention group study population was identified using retrospective administrative pharmacy claims data from a commercial Blue Cross Blue Shield (BCBS) plan in the southern United States. This health plan had an average of 1.4 million members per month and implemented a linezolid PA policy on January 1, 2009. A concurrent comparison group was identified from a different commercially insured BCBS population in the Midwest United States with an average of 1 million members per month that did not implement the linezolid PA program. For both the intervention and comparison groups, members were required to be continuously enrolled for 6 months prior to their index linezolid claim.

The PA policy rejected all linezolid claims at the point of sale. A prescriber was required to contact the health plan and request coverage. The PA policy stated that the intent of the linezolid PA was to ensure appropriate selection of patients for treatment according to product labeling and/or clinical studies and/or guidelines. Appropriate use was defined as treatment of a serious, life-threatening infection or sepsis due to vancomycin-resistant Enterococcus faecium or Enterococcus faecalis, or a documented infection due to Staphylococci that are resistant to beta-lactams, macrolides, clindamycin, and co-trimoxazole (eg, methicillin-resistant Staphylococcus aureus [MRSA]). Oral tablet and oral suspension dosage forms were included in the program, and approval—when granted—was for 6 months.

During the period of January 1, 2011, through June 30, 2011, each member’s earliest linezolid pharmacy claim that was rejected (for the intervention group) and paid (for the comparison group) was identified and defined as the index claim. All pharmacy claims were identified using the assigned Generic Product Identifi er (GPI, Medi- Span, Indianapolis, Indiana), starting with 1623. Member characteristics from the index claim included age, gender, and zip code–derived median income and education. Charlson Comorbidity Index (CCI) score was calculated in the pre-6–month period.17,18 The baseline number of outpatient visits, hospitalizations, and emergency department (ED) visits were also collected in the 6 months prior to the index linezolid claim. Members’ infectious organism(s) were collected using International Classification of Diseases, Ninth Revision (ICD-9) codes found in the 6 months prior to the index claim in any field of the member’s medical claims. Infectious organisms were hierarchically ordered and categorized as follows: (1) infections with drug-resistant organisms specific to vancomycin, MRSA pneumonia, MRSA septicemia, or MRSA carrier status; (2) infections due to undefi ned organisms; and (3) all other infectious organisms.

To assess the drug-use patterns following the index claim, all pharmacy and medical claims were queried during the 30 days after the index date for the presence of drug supply for linezolid or any other antibiotic agent. Linezolid medical claims were identified using the Healthcare Common Procedure Coding System (Level II) J2020 code. For evaluating drug supply presence on specific follow-up dates, an end date for each claim (ie, fill date plus days of supply on the claim) was created. On each day evaluated after the index date (ie, day 30 and 60), presence of linezolid and any other antibiotic was reported in the following hierarchical order: (1) linezolid with or without another antibiotic; (2) other antibiotics (without linezolid); and (3) no antibiotic therapy. Hospitalizations and ED visits were identifi ed in the medical claims using revenue codes or place-of-service codes when revenue codes were not available. Outpatient visits were also identifi ed using medical claims Current Procedural Terminology codes (99201 through 99205 and 99211 through 99215). Economic outcomes were evaluated in the follow-up periods using all pharmacy and medical claims and total paid amounts (member share plus health insurer payment). Costs specific to linezolid and all other antibiotics are reported separately. Linezolid and all other antibiotic costs from both the pharmacy and medical benefi t were identifi ed and reported. Total cost included all pharmacy plus all medical costs.

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