Quantifying Imaging’s Value to Patients

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Contrary to popular belief among regulators and payors, imaging studies do, in fact, contribute to improved patient care, according to a to-be-published study, “The Association Between Hospital Outcomes and Diagnostic Imaging: Could More Be Better?” by David W. Lee, PhD, and David Foster, PhD.

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David Lee, PhD

The study’s results indicate that the risk-adjusted probability of receiving an imaging service has a statistically significant inverse correlation with risk-adjusted mortality for all four modalities studied (CT, MRI, ultrasound, and radiography). Utilization of imaging services was correlated with reductions in costs and lengths of stay, though none of the correlations between imaging and cost achieved statistical significance.

The authors hope that this work inspires others to investigate further by approaching the issue from different angles. Lee, senior director of health economics and outcomes research for GE Healthcare, Waukesha, Wisconsin, says, “If anything, our study highlights the need for further assessment of whether and how diagnostic imaging shapes key clinical, operational, and economic outcomes in the inpatient setting.” The study has been accepted for publication by a peer-reviewed journal, Lee reports.

Sparked by Doubts

Lee says that he became interested in conducting this study because of the rising doubts about the value of imaging coming from government and the insurance industry. “Between 2000 and 2006, the use of advanced imaging technologies—such as CT, MRI, PET, and SPECT—grew at more than twice the rate for physician services overall per Medicare beneficiary,” he reports. “As we all know, this spurred Congress to reduce payments significantly for diagnostic imaging services. At the same time, this utilization trend prompted payors and policymakers to begin questioning whether more diagnostic imaging is at all associated with better health outcomes.”

Lee notes that the foes of upward utilization trends have been bolstered in their assumptions by dint of a body of literature (no single study in particular) suggesting that when it comes to health care resources in general and imaging specifically, delivery of more does not necessarily result in better outcomes. “Our study was an attempt to focus in on diagnostic imaging in the inpatient setting and see whether that’s true or whether the opposite is the case,” Lee says.

Testing the Hypothesis

The study by Lee and Foster tests whether more is better in diagnostic imaging. It does this by examining the association between the utilization of inpatient diagnostic imaging services and three key hospital outcome measures: mortality, length of stay, and cost.

“We used patient-level data to construct a pair of hospital-specific, risk-adjusted imaging-utilization measures for CT, MRI, ultrasound, and radiography: a binary indicator of whether the patient received the service and an estimate of the mean number of services received,” Lee explains. “Both were adjusted for the patients’ demographic characteristics, severity level, and discharge disposition of death, as well as for hospital characteristics.”

The necessary data were culled from the Thomson Reuters 2007 Hospital Drug Database, which covers 1.1 million patients treated at 102 US hospitals. “Nearly 54% of these patients were female, and almost 33% were between the ages of 45 and 64, with another 29.9% between 70 and 84 years old,” Lee notes. “The hospitals ranged from fewer than 200 beds to more than 500 beds. Some were teaching institutions; many were community hospitals. Most were located in the South, but there was a nice mix of urban and rural hospitals.”

Lee and Foster chose to sift through the Thompson Reuters database instead of visiting and surveying a cohort of hospitals for reasons of efficiency. “This database—which was available to us in electronic form—offered very detailed information on basically every intervention and service delivered to the 1.1 million patients during each stay,” Lee says. “Included among those interventions and services were the imaging procedures the patients received. Also provided was information about the outcome of care, and how much that care cost.”

Ensuring Soundness

So that the findings of their investigation would withstand scrutiny, Lee and Foster sought to design the study in such a way that pertinent factors and variables (from one hospital to the next) affecting both the utilization of imaging and patient outcomes would