Original Contribution
Diagnostic imaging rates for head injury in the ED and states' medical malpractice tort reforms

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Abstract

Objective

Physicians' fears of being sued may lead to defensive medical practices, such as ordering nonindicated medical imaging. We investigated the association between states' medical malpractice tort reforms and neurologic imaging rates for patients seen in the emergency department with mild head trauma.

Methods

We assessed neurologic imaging among a national sample of 8588 women residing in 10 US states evaluated in an emergency setting for head injury between January 1, 1992, and December 31, 2001. We assessed the odds of imaging as it varied by the enactment of medical liability reform laws.

Results

The medical liability reform laws were significantly associated with the likelihood of imaging. States with laws that limited monetary damages (odds ratio [OR], 0.63; 95% confidence interval [CI], 0.40-0.99), mandated periodic award payments (OR, 0.64; 95% CI, 0.43-0.97), or specified collateral source offset rules (OR, 0.62; 95% CI, 0.40-0.96) had an approximately 40% lower odds of imaging, whereas states that had laws that limited attorney's contingency fees had significantly higher odds of imaging (OR, 1.5; 95% CI, 0.99-2.4), compared to states without these laws. When we used a summation of the number of laws in place, the greater the number of laws, the lower the odds of imaging. In the multivariate analysis, after adjusting for individual and community factors, the total number of laws remained significantly associated with the odds of imaging, and the effect of the individual laws was attenuated, but not eliminated.

Conclusion

The tort reforms we examined were associated with the propensity to obtain neurologic imaging. If these results are confirmed in larger studies, tort reform might mitigate defensive medical practices.

Introduction

Diagnostic imaging has increased significantly over the past 2 decades and contributes substantially to overall medical costs [1], [2], [3]. According to the Centers for Medicare and Medicare Services, the growth in the volume of imaging services per Medicare beneficiary outstripped the growth of all other services [4], [5]. Many factors have contributed to the increase in imaging, including improvements in imaging technology, greater availability of computed tomography (CT) and magnetic resonance (MR)[6], and increased patient- and physician-generated demand, resulting in a lowering in the threshold for its use. Physicians' fears of being sued also may lead to defensive medical practices, such as ordering nonindicated medical imaging [7], [8], [9]. Thus, some of the increase in imaging may be driven by physicians' fears of malpractice lawsuits and their adoption of defensive, medically nonindicated test ordering to avoid lawsuits [7], [8], [9].

Defensive medicine has been reported frequently in the United States [8], [9], [10]. In a 1992 Gallup pole, 84% of physicians said that the threat of medical liability suits causes them to order tests they might consider unnecessary [10], and a recent survey of physicians practicing within 6 high-risk medical specialties found nearly all physicians reported defensive medical practices [9]. Ordering of more diagnostic tests than was medically indicated was the most frequently reported defensive medical practice, and emergency department (ED) physicians were significantly more likely than other specialists to report nonindicated medical test ordering [9]. Other reports have also found that ED physicians are particularly likely to report defensive medical practices [8], [11].

There have been few studies on the association between specific tort reforms and indirect malpractice costs, such as those that result from so-called defensive medical practices. The US Office of Technology Assessment concluded it is impossible to accurately measure the costs of defensive medicine [8], but it is widely believed to account for a much larger percentage of health care costs than the direct costs. For example, whereas the direct costs (such as premiums and award payouts) associated with malpractice are estimated to represent approximately 1% of health care costs [8], indirect costs, such as those that result from defensive medical practices, are estimated to account for a much higher proportion of health care costs, and as much as 5% of health care costs, or $5 to $50 billion dollars annually [12], [13], [14], [15].

To assess defensive medical test ordering, we investigated the association between states' medical liability tort reforms and neurologic imaging rates for patients seen in the ED with head trauma. We studied neurologic imaging among head trauma patients; because it is a prevalent condition [16], guidelines exist for the use of imaging in this setting allowing at least crude separation between indicated and nonindicated imaging [17], [18], and ED physicians are specialists who experience high levels of litigation and report frequent defensive test ordering [9]. We hypothesized that imaging rates would be higher when imaging was indicated but that imaging rates would also vary by the specific tort reforms enacted.

Section snippets

Methods

Medicare billing claims provide a convenient source of information to evaluate the use of neurologic imaging among elderly adults. A representative 5% sample of Medicare-eligible adults 65 years and older living in 10 US states (Table 1), representing approximately 14% of the US population, was used to complete this study. These data were originally obtained for an unrelated project evaluating breast cancer screening and treatment [19], [20], thus limiting the sample to female Medicare

Results

Among the 274 590 Medicare beneficiaries in our cohort, 8588 women (3.1%) were evaluated in an ED for head injury between 1992 and 2001, including 1835 who had a severe injury (Table 2). Neurologic imaging increased substantially over the study period (Fig. 1). Imaging increased approximately 22% among patients with severe injury (73% to 89%) and 79% among patients with a mild-moderate injury (38% to 68%) over the 9-year period.

In the unadjusted analyses, patient age and income were not

Discussion

The American College of Emergency Physicians has developed guidelines for neurologic imaging for patients seen in an ED with head injury [17]. These guidelines recommend that imaging should be obtained when there is a severe injury, but that imaging should be considered discretionary in other cases, as the risk of detecting significant or treatable disease is low [18]. Although the guidelines are relatively recent, they provide a reasonable way to separate situations where imaging is clearly

Acknowledgment

The authors would like to thank Dr James Brenner for his helpful comments on an earlier version of the manuscript.

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