The cost of an itch: A nationally representative retrospective cohort study of pruritus‐associated health care expenditure in the United States

Abstract

To the Editor: Pruritus arises from many common diseases and is reported as a symptom in [7 million outpatient visits annually in the United States. The impact of pruritus on quality of life is substantial and comparable with that of chronic pain. Although there are limited studies regarding its epidemiology, pruritus has an estimated lifetime prevalence of 25.5% and most commonly affects patients who are female, elderly, and of lower socioeconomic status. Despite the significant health and biopsychosocial burden posed by pruritus, limited information exists regarding its economic burden. As such, the goal of this study was to provide nationally representative estimates of the incremental health care burden of pruritus controlling for sociodemographic characteristics and comorbidities. In this study, we used 9 years of data from the Medical Expenditure Panel Survey (MEPS; 2007-2015), a nationally representative survey assessing patterns of utilization of outpatient care in the United States. The methods of administration for MEPS are detailed elsewhere. All analyses were done in R accounting for the complex survey design of MEPS to provide nationally representative samples. We compared sociodemographic characteristics of patients with pruritus (International Classification of Disease Ninth Revision, Clinical Modification code 698) to those without pruritus using Rao-Scott chi-squared tests. To determine the adjusted incremental inflation-adjusted expenditure (in USD) of pruritus controlling for all other factors, we constructed a 2-part linear regression model to account for the high concentration of zero expenditures in the data. Our 2-part model consists of logistic regression to predict the likelihood of nonzero expenditures and a generalized linear model to predict conditional nonzero expenditures. A generalized linear model with a gamma distribution and log-link function was used to address the positive skewness of the expenditure data. Our model was used to estimate expenditure ratios, which represented the adjusted multiplicative effect of a variable compared with the reference class. For example, an expenditure ratio of 2 would indicate that patients with pruritus had twice the health care expenditure of patients without pruritus, controlling for other factors. The advantages of this validated 2-part model have been previously described. In total, our sample included 637 patients with pruritus and 288,061 patients without pruritus. Women, older adults, nonwhite patients, Medicaid and Medicare patients, patients with less education, and patients with more comorbidities were all more likely to have pruritus (P\\ .001 for all, Table I). Controlling for Charlson Comorbidity Index and all sociodemographic factors, the cost of care for patients with pruritus is 1.64 times as high as patients without pruritus (P \\ .001, Table II). Although emergency room and home health service expenditures due to pruritus have increased over time, expenditures due to pruritus in both the outpatient and inpatient setting have decreased. Pruritus is a significant burden to both medical and financial health. Patientswith pruritus are estimated to face $4,843.68 (adjusted for inflation) more in annual health care expenditures than patients without pruritus, even after controlling for comorbidities and sociodemographic factors. When accounting for even the most conservative national estimates of chronic pruritus (6.1%), our data suggests that pruritus is associated with [$90 billion per year in population-level expenditures in the United States. Strengths of this study include analysis of a large, nationally representative data set to provide cost estimates. A limitation is that unmeasured confounders might have overestimated the incremental cost, given the demographic differences between the pruritus and nonpruritus patient population found in this study. Elucidating the health care costs due to pruritus is vital, considering its association with numerous chronic diseases. Although the incremental cost associated with pruritus has remained steady, expenditures due to pruritus seem to be shifting from outpatient and inpatient settings to the emergency room and home health services. As overall health care costs continue to rise, it is critical to identify effective strategies to improve the control and management of pruritus.