Prescription Opioids and Traumatic Brain Injury in Older Adults

Abstract

Older adults using opioids in the US increased annually from 1999 to 2011. This is a significant public health concern because prescription opioid use increases fall-risk, the most common cause of traumatic brain injury (TBI) among older adults and a leading cause of disability and mortality. No studies have investigated the association between prescription opioid use and TBI. This dissertation characterized prescription opioid use in Medicare beneficiaries aged ≥65 years and examined the relationship between opioid use and incident TBI. Using Medicare administrative claims data from 2010 – 2015, I assessed how older adult prescription opioid use has changed over time, as well as changes in opioid prescriber specialties and pre-opioid diagnoses/ procedures. I also used these data to estimate risk for TBI associated with prescription opioid use. Next, I used R Adams Cowley Shock Trauma Center Registry (STR) data from 2015 – 2019 to explore the relationship between prescription opioid use and TBI injury mechanisms and severity. I found that the percent of older adults using prescription opioids decreased from 35.4% to 32.9% (p<0.001). Primary care physicians prescribed the most opioids, but their share of prescriptions dropped from 59.0% to 52.8% (p<0.001). Back pain remained the most common diagnosis among older adult opioid users, unchanged over time (24.1% to 25.3%, p=0.594). Opioid use increased TBI risk (odd ratio: 1.34, 95% confidence interval: 1.28 - 1.40) among older adults, regardless of opioid dosage and duration differences. Compared to non-users in the STR data, older adult opioid users who sustained TBI were 85% more likely to be injured in a fall compared to a motor vehicle incident (OR 1.85, 95% CI 1.20 – 2.86). Opioid use was associated with a 39% increase in sustaining more severe TBIs. (OR 1.39, 95% CI 1.09 – 1.79). This dissertation found opioid prescriptions decreasing among older adults. This parallels reductions in primary care opioid prescribing as well as changes in opioid-related diagnoses and procedures. These are the first studies to provide evidence that prescription opioids raise TBI risk and severity in older adults. Future studies could refine the association between opioid and TBI using data with definite dosing details