Trends in Prescription Drug Use among Adults in the United States from 1999–2012

Abstract

Importance

It is important to document patterns of prescription drug use to inform both clinical practice and research.

Objective

To evaluate trends in prescription drug use among adults living in the United States.

Design, Setting, and Participants

Temporal trends in prescription drug use were evaluated using nationally representative data from the National Health and Nutrition Examination Survey (NHANES). Participants include 37,959 non-institutionalized US adults, aged 20 years and older. Seven NHANES cycles were included (1999–2000 to 2011–2012), and the sample size per cycle ranged from 4,861 to 6,212.

Exposures

Calendar year, as represented by continuous NHANES cycle.

Main Outcome(s) and Measure(s)

Within each NHANES cycle, use of prescription drugs in the prior 30 days was assessed overall and by drug class. Temporal trends across cycles were evaluated. Analyses were weighted to represent the US adult population.

Results

Results indicate an increase in overall use of prescription drugs among US adults between 1999–2000 and 2011–2012 with an estimated 51% of US adults reporting use of any prescription drugs in 1999–2000 and an estimated 59% reporting use in 2011–2012 (Difference: 8%; 95% CI: 3.8%–12%; p-trend<0.001). The prevalence of polypharmacy (use of ≥5 prescription drugs) increased from an estimated 8.2% in 1999–2000 to 15% in 2011–2012 (Difference: 6.6%; 95% CI: 4.4%–8.2%; p-trend<0.001). These trends remained statistically significant with age adjustment. Among the 18 drug classes used by more than 2.5% of the population at any point over the study period, the prevalence of use increased in 11 drug classes including antihyperlipidemic agents, antidepressants, prescription proton-pump inhibitors, and muscle relaxants.

Conclusions and Relevance

In this nationally representative survey, significant increases in overall prescription drug use and polypharmacy were observed. These increases persisted after accounting for changes in the age distribution of the population. The prevalence of prescription drug use increased in the majority of, but not all, drug classes.