Prevalence, predictors, and consequences of propoxyphene use in the aged

Abstract

Propoxyphene, an opiate-like analgesic, is considered inappropriate among patients 65 years or older. Despite this, propoxyphene is commonly prescribed among elderly patients. The objectives of this study were (1) to estimate the prevalence and persistence of propoxyphene use, (2) to determine patient and physician characteristics and the main clinical indications associated with propoxyphene use, and (3) to establish whether propoxyphene use is associated with an increased risk of fractures in elderly persons. The Medicare Current Beneficiary Survey (MCBS), a nationally representative dataset of the Medicare population, and the Area Resource File, which provided county-level physician characteristics, were used to estimate the prevalence and predictors of propoxyphene use. Since drug events are not dated in the MCBS, the MarketScan, an employer-based claims dataset was used to examine persistence of propoxyphene use, indications for its use and its association with fractures. Descriptive and multivariate (logistic and time-dependent Cox regression) analyses were conducted. The results indicated a high prevalence of propoxyphene use in the community-dwelling elderly Medicare population, with over 2 million beneficiaries receiving it in each year from 1993(6.8%) to 1999(6.5%). More than half the propoxyphene users had only one prescription in the year and the mean prescription was written for 11 days supply. Beneficiaries most likely to fill propoxyphene included: females, Medicaid beneficiaries, residents of the South and Midwest, and those with history of osteoporosis and hip fractures. Beneficiaries residing in counties where the proportion of medical specialists was higher were less likely to receive propoxyphene. The most common indications for propoxyphene were cancer, back disorder, osteoarthritis, and joint pain. Cox regression results indicated a 2.5 times increase in the hazard of fractures for persons who used propoxyphene in the last 14 days as compared to those who did not (HR 2.5; 95%CI 2.4--2.7). A positive dose-response relationship was also observed between propoxyphene use and risk of fractures. These results should help design and target interventions to reduce propoxyphene use in elders. Establishing an increased risk of fractures should strengthen the case for these interventions.