Psychological Distress and Trends in Healthcare Expenditures and Outpatient Healthcare
Published Online: May 23, 2011
Paul A. Pirraglia, MD, MPH; John M. Hampton, MS; Allison B. Rosen, MD, ScD; and Whitney P. Witt, PhD, MPH
A critical first step in assessing the value of healthcare in the United States as it relates to mental health is determining whether trends in mental health symptoms have had an impact on changes in healthcare expenditures over time. It is well recognized that healthcare costs have been increasing,1 with an average growth rate of 5.4% in healthcare expenditures between 1993 and 2000.2 Mental health spending has increased as part of total spending, though at a lower rate.3 Spending on prescription drugs to treat mental health and substance abuse conditions increased markedly between 1996 and 2000.4 Mental health conditions—including depression,5-7 anxiety,5,8 bipolar disorder,9-11 and schizophrenia12have been linked to higher healthcare costs. These higher costs are not attributable solely to higher mental health costs. While some reports suggest that the prevalence of mental health conditions in the United States is stable,13 there is also evidence that mental distress has increased over time.14
Given the increased use of prescription medications to treat depression, anxiety, psychotic illnesses, and other mental health conditions, one might expect that while the prevalence of mental health conditions might not change, the overall burden of mental health symptoms might decline over time. Therefore, since healthcare costs are known to be increasing, a trend toward improving value of healthcare as it relates to mental health would be reflected by a relationship between mental health symptoms and expenditures; that is, either the proportion of those with elevated mental health symptoms would decrease over time or the spending for those with a greater burden of mental health symptoms would drop over time relative to those individuals with fewer symptoms.
Quantifying how mental health plays a role in changing healthcare costs is not easily done. Consideration of the impact of diagnosed mental health conditions over time may be influenced by changes in screening and in recognition, as well as shifts in nosology. Examining only diagnosed or self-reported conditions also misses the impact of mental health conditions that are undiagnosed or unreported. Furthermore, how mental health may be related to healthcare expenditures is not solely determined on the basis of having a mental health condition, but on the burden of mental health-related symptoms; that is, severity of symptoms may bea key determinant for related expenditures, which has been shown, for example, in depression15 and bipolar disorder.16 Because healthcare expenditures and utilization in those with known mental health conditions tend to be higher, overall costs must be evaluated.
We sought to examine trends in overall mental health and subsequent healthcare expenditures in the United States by using linked data from 2 nationally representative surveys of noninstitutionalized individuals, the National Health Interview Survey (NHIS) and the Medical Expenditure Panel Survey (MEPS). These linked surveys are well suited to address trends in mental health and expenditures. Starting in 1997, a 6-item scale of the Kessler Psychological Distress Scale (K6), a shortened form of a previously developed 10-question psychological distress scale, was introduced into NHIS, which provides a measure of psychological distress that has been validated with respect to mental health diagnoses.17 Starting in 1996, MEPS used the NHIS sampling frame to track national health expenditures. Using these linked data sets, we sought to examine whether there has been a change over time in psychological distress in the United States and whether adjusting for factors known to be associated with mental disorders would impact a trend in psychological distress if it were observed. We also sought to examine whether there were trends in healthcare expenditures and outpatient visits associated with the level of psychological distress, with the expectation that good value in healthcare related to mental health symptoms would be reflected by either a decrease over time in the population burden of psychological distress or a reduction over time in subsequent healthcare costs and expenditures
among those with greater psychological distress.
Data Source and Study Sample
We performed a sequential cross-sectional study wherein we examined 8 consecutive years of data. Data are from NHIS and MEPS, both of which provide nationally representative data. NHIS data are collected on a new sample each year, and MEPS uses a subset of this sample in the 2 subsequent years. While the MEPS data are a subset of the NHIS sample, MEPS still uses a survey sample design such that the weighted values are nationally representative, which minimizes selection bias that might occur with selection of the MEPS subsample. 18 We obtained NHIS data from 1997 through 2004, which provided information on psychological distress (described below), and the 2 subsequent years of MEPS data for each of these samples to obtain subsequent utilization and expenditure data. We limited our study to those persons 18 years and older, resulting in weighted data representing 25,618,369 adults. The study was exempted from institutional review board approval as the data were publicly available and participants could not be identified from the data.
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