Abstract Information


Incidence of adverse drug events with polypharmacy differs between persons with and without spinal cord injury

Hand B, Krause J, Simpson K
Medical University of South Carolina, Charleston, SC, USA

Background: Polypharmacy is commonly defined as the concomitant use of five or more prescription drugs (1). Numerous negative health consequences are associated with polypharmacy, including: increased risk of falls, adverse drug events (ADEs), hospitalization, mortality, declines in functional status, and impaired cognition (2). While prescription of multiple medications is common in treating patients with spinal cord injury (SCI), until recently, relatively little was known about the incidence of polypharmacy in this population. Recent work suggests that 30% of adults with pediatric onset SCI (3) and 56% of persons with adult onset traumatic or nontraumatic SCI (4) take five or more concomitant medications. Additionally, findings revealed that differences in the number of prescription medications (4) and medical comorbidities (3) are important, potentially confounding variables that should be considered when comparing risk for ADE between persons with and without SCI. Findings from studies of other diagnostic populations suggest that hospitalizations (5), age (1), gender (6), and geographic region of residence (7) are also important characteristics to consider. Objective: The objective of this study is to compare the incidence of adverse drug events ADEs between persons with and without SCI, while controlling for all potential and available risk factors. Methods: Data used for the analysis were derived from Thompson Reuters MarketScan(R) Commercial Claims and Encounters Databases for the years 2012-2013. Participants (aged 18-64 years) included 3,282 persons with polypharmacy and traumatic or nontraumatic SCI and 3,282 propensity score matched persons with polypharmacy without SCI. The cohorts were matched using demographic variables including number of concomitant prescriptions, comorbidities, hospital admissions, age, gender, and geographic region. Inpatient and outpatient claims records containing 395 distinct IDC-9 codes indicative of ADEs were extracted. Incidence and frequency of ADEs were compared between groups using logistic and Poisson regression, respectively. Results: Persons with SCI were significantly more likely to experience an ADE than matched controls (OR=1.38, p<0.0001). Among persons with ADEs (n=1,886), individuals with SCI experienced fewer ADEs over time than matched controls (coefficient=-0.11, p=<0.0001). Conclusions: While persons with SCI and polypharmacy are at a greater risk for experiencing an ADE, their medical care after an ADE may be better managed than that of a matched control population. Findings suggest a need for practice guidelines that facilitate proactive identification of persons with SCI at the highest risk of ADE. Steps may then be taken to mitigate risk, in contrast to current practice trends that appear to take a reactive approach after an ADE has occurred. Support: This work was supported by the South Carolina Spinal Cord Injury Research Fund, grant number #2016 PD-01 and the South Carolina Clinical & Translational Research (SCTR) Institute, through NIH - NCATS Grant Number UL1 TR001450. Data analytic support for the study was provided through the CEDAR core, funded by the MUSC Office of the Provost.


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