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 included 37,959 noninstitutionalized 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 4861 to 6212.

Exposures: Calendar year, as represented by continuous NHANES cycle.

Main outcomes and measures: 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 of any prescription drugs in 2011-2012 (difference, 8% [95% CI, 3.8%-12%]; P for trend <.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 for trend <.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.

Figure 1. Trends in Any Prescription Drug Use and Use of ≥5 Prescription Drugs, Overall, and by Age Group, Sex, and Race/Ethnicity (1999–2012)^a

Panel A presents trends in any prescription drug use and use of ≥5 prescription drugs among US adults. Panel B presents trends in any use and in use of ≥5 prescription drugs, by age group (≥20–39, ≥40–64, ≥65 y). Panel C and Panel D present trends for any use and use of ≥5 prescription drugs, by sex and race/ethnicity (non-Hispanic white, non-Hispanic black, Mexican American), respectively. All trends statistically significant, except for any prescription drug use among persons ages 20–39 (p-trend=0.22) and for any prescription drug use among Mexican Americans (p-trend=0.17). ^a All data are weighted to be nationally representative.

Figure 2. Trends in individual prescription medications used by >4% of US adults in 2011–2012^a

Figure 2 presents temporal trends in prevalence of use for drugs used by >4% of US adults in 2011–2012. All trends were statistically significant (p-trend for each drug<0.001). ^a All data are weighted to be nationally representative.