Several recent studies have made clear that drug expenditures are rising mo
re rapidly than other health care spending. What has not been clear, howeve
r, is how much drug spending is driven by price rather than volume and whet
her volume increases are appropriate. This DataWatch takes a closer look at
the components and drivers of drug spending using large claims databases f
rom managed care and employer-sponsored health benefit plans. In both envir
onments this study found volume, not price, to be the largest driver of dru
g spending for seven diseases studied. For four of the diseases, we review
the clinical issues that may have influenced volume growth.