Trends of medical expenditures and quality of life in US adults with diabetes: the medical expenditure panel survey, 2002–2011

BACKGROUND: Studies indicate a relationship between cost and quality of life (QOL) in diabetes care, however, the interaction is complex and the relationship is not well understood. The aim of this study was to 1) examine the relationship of quartiles of QOL on cost amongst U.S. adults with diabetes, 2) investigate how the relationship may change over time, and 3) examine the incremental effect of QOL on cost while controlling for other relevant covariates. METHODS: Data from 2002-2011 Medical Expenditure Panel Survey (MEPS) was used to examine the association between QOL and medical expenditures among adults with diabetes (aged ≥18 years) N = 20,442. Unadjusted means were computed to compare total healthcare expenditure and the out-of-pocket expenses by QOL quartile categories. QOL measures were Physical Component Summary (PCS) and Mental Component Summary (MCS) derived from the Short-Form 12. A two-part model was then used to estimate adjusted incremental total healthcare expenditure and out-of-pocket expenses adjusting for relevant covariates. RESULTS: Differences between the highest and lowest quartiles totaled $11,801 for total expenditures and $989 for out-of-pocket expenses. Over time, total expenditures remained stable, while out-of-pocket expenses decreased, particularly for the lowest quartile of physical component of QOL. Similar trends were seen in the mental component, however, differences between quartiles were smaller (average $5,727 in total expenses; $287 in out-of-pocket). After adjusting for covariates, those in the highest quartile of physical component of QOL spent $7,500 less, and those in the highest quartile of mental component spent $3,000 less than those in the lowest quartiles. CONCLUSIONS: A clear gradient between QOL and cost with increasing physical and mental QOL associated with lower expenditures and out-of-pocket expenses was found. Over a 10-year time period those with the highest physical QOL had significantly less medical expenditures compared to those with the lowest physical QOL. This study demonstrates the significant individual and societal impact poor QOL has on patients with diabetes. Understanding how differences in a subjective measure of health, such as QOL, has on healthcare expenditures helps reveal the burden of disease not reflected by using only behavioral and physiological measures.