Marked Increase in Prescription Drugs and Polypharmacy in US Adults

MedicalResearch.com Interview with:
Dr. Elizabeth D. Kantor PhD MPH
Assistant Attending Epidemiologist
Memorial Sloan Kettering Cancer Center

Medical Research: What is the background for this study? What are the main findings?

Dr. Kantor: We know that use of prescription drugs represents a major expenditure in the United States and research suggests that use of prescriptions has increased. However, much of what we know is derived from information on expenditures, is outdated, or is limited to certain populations, such as older adults or those with a given clinical condition. For example, a number of studies have looked at things like use of drugs used to control condition x among persons with condition x, but that doesn’t tell us about use of that class of drugs in the population.

It’s important that we continue to monitor use of prescription drugs in the population, as practice patterns are continually evolving as the population ages, the health needs of the population change, drugs enter/exit the market, scientific knowledge advances, and policies change. We therefore sought to create an updated comprehensive reference on prescription drug use among US adults using nationally representative data from the National Health And Nutrition Examination Survey, a continuous survey conducted by the Centers for Disease Control and Prevention. We examined trends in use of prescription drugs over 7 cycles, ranging from 1999-2000 to 2011-2012 (the sample size per cycle ranged from 4,861 to 6,212).Participants were asked about use of prescription medications over the prior 30 days, from which we were able to estimate the prevalence of use within each survey cycle. We then looked at trends in prescription drug use, both overall and within drug classes.

In our study, we observed that use of any prescription medications increased over the study period, with 51% of adults reporting any prescription medication use in 1999-2000 and 59% reporting any use in 2011-2012. We also observed an increase in polypharmacy (or use of 5 or more prescription drugs) over the study period, with approximately 8% of adults reporting use of 5 or more drugs in 1999-2000, as compared to 15% in 2011-2012. Polypharmacy was much more common among older adults: 24% of adults ages 65 and older reported use of 5 or more drugs in 1999-2000 and 39% reported use of 5 or more drugs in 2011-2012. At first glance, one might take a look at these results and think that this is probably because the US population is aging and people tend to take more drugs as they age. But we found that the increase in overall prescription drug use and polypharmacy persisted even after accounting for the aging of the US population. This means that something else is driving the observed increase in use of prescription drugs.

We also found that use of the majority of drug classes increased over the study period. For example, among commonly used drug classes, we observed marked increases in use of drugs taken to control high cholesterol, high blood pressure, and diabetes. We also observed marked increases in some less commonly used drug classes, such as muscle relaxants. Interestingly, if we look at the ten most commonly used drugs in 2011-2012, we can see that most are taken for conditions associated with cardiometabolic disease This raises the question of how much of this increase in prescription drug use may be attributable to overweight/obesity, as we know that the prevalence of obesity has increased among US adults.

Medical Research: What should clinicians and patients take away from your report?

Dr. Kantor: Use of prescription drugs has increased, as has use of 5 or more drugs. This increase persists even accounting for the changing age structure of the US population. We also observed an increase in the majority of drug classes.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Kantor: We created a comprehensive report, and have examined trends not just overall, but also within drug classes and by population subgroups (age, sex, and race/ethnicity). I think that there are many interesting trends observed and I hope that these findings can inform both researchers and clinicians alike.

Citation:

 

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Dr. Elizabeth D. Kantor PhD MPH (2015). Marked Increase in Prescription Drugs and Polypharmacy in US Adults