Results on value of stroke imaging may be misleading

Economic evaluations of stroke imaging modalities are generally of high quality, but shortcomings may lead to inaccurate results, according to a review published in the March issue of Stroke.

Senior author Andreas Laupacis, MD, MSc, of the Institute of Health Policy, Management and Evaluation in Toronto, and colleagues described neuroimaging-focused economic studies as in their infancy but important for optimal management of patients with acute ischemic stroke. They conducted a systematic review and analysis to assess the quality of economic evaluations and identify opportunities for improvement.

They searched MEDLINE, EMBASE, OVID HealthSTAR, CINAHL, Tufts Medical Center Cost Effectiveness Analysis Registry, the British National Health Service Economic Evaluation Database and Econlit from various starting dates through July 2012 for comparative cost-effectiveness analyses of stroke imaging strategies.

They selected five studies and applied a scoring system used by the British Medical Journal to determine methodological quality. The median quality score was 84.4 percent, which they considered to be generally high quality, but they also identified numerous opportunities to improve accuracy.

Each of the studies compared noncontrast CT to another modality but none included all relevant comparators. They highlighted time between symptom onset and imaging, the impact of imaging results on treatment and clinical outcomes and imaging utility as important considerations as well.

“These factors should be considered in any future economic evaluations of stroke imaging, specifically: (1) the sensitivity and specificity of any imaging modality used; (2) the proportion of imaging studies that are interpretable; (3) the additional time taken to acquire, process, and interpret multimodal imaging techniques,” they proposed.

Evaluations using CT perfusion as a comparator lacked high-quality outcome data. Other studies failed to address complications such as contrast-induced nephropathy, radiation exposure, bailout from claustrophobia and stroke recurrence, all of which carry cost implications.

“[B]ecause of several clinical and radiological limitations, these studies need improvement, and their results may be misleading,” they warned. They added that their analysis also had limitations, including the use of a scoring tool that has not been validated.