Does defensive medicine protect doctors against malpractice claims?

In a linked paper in this issue, Jena and colleagues (doi:10.1136/bmj.h5516) examine a longstanding, unanswered question about the US malpractice system: if doctors spend more, will they reduce their risk of being sued?1 This is an important question that explores the contentious issues of defensive medicine and the risk of malpractice claims in the US healthcare system.

Defensive medicine refers to medical care performed primarily to reduce the risk of litigation. Positive defensive medicine occurs when doctors perform more tests or procedures than are necessary. Negative defensive medicine occurs when doctors avoid high risk procedures or refuse to care for high risk patients. Most doctors in the United States state that they practise defensive medicine, and it is estimated that $60b (£39b; €54b) is spent annually on defensive medicine.2 3 Although the US is considered a highly litigious environment, clinicians in other countries also report practising defensively.4

Most research has looked at the prevalence of defensive medicine and the impact of malpractice reforms on the magnitude of defensive medicine. However, an important unanswered question is whether defensive medicine is effective at reducing the risk of malpractice claims.

The current study complements other studies that explore factors contributing to the risk of malpractice claims. For example, a previous study by Jena and colleagues found that specialty is an important predictor of risk for malpractice claims—doctors in surgical specialties were over five times more likely than those in non-surgical specialties to have an active malpractice claim against them.5 Other studies find that poor patient-doctor communication is associated with a higher risk of malpractice claims.6 7 However, none of these studies investigated whether higher spending and intensity of care reduced the risk.

The study by Jena and colleagues specifically explores whether higher spending by doctors correlates with a reduced risk of malpractice claims. Using data from the state of Florida, the authors created two measures of intensity of care provided by doctors: risk adjusted patient charges and caesarean section rates. The authors then explored the association between these rates and the future probability of the doctor being sued.

The findings are noteworthy. Among doctors in six out of seven specialties, those in the highest fifth of spending had the lowest rates of malpractice claims. For example, internal medicine doctors in the highest spending fifth were five times less likely to be sued than their colleagues in the lowest spending fifth. Similar associations were seen among paediatricians, surgeons, and obstetricians. Family medicine doctors were the only clinicians in whom this association was not observed.

When the researchers looked specifically at caesarean section rates, commonly considered to represent defensive practice among obstetricians, they found almost half the rate of malpractice claims among obstetricians in the highest compared with the lowest fifth of caesarean sections.

The study by Jena and colleagues is the first to substantiate a common assumption that if doctors spend more and use more resources, they are less likely to be sued. Before we can broadly conclude this is truly the case, however, there are some things to consider.

Firstly, the authors measure resource use in the forms of spending by doctors and caesarean section rates. It is not possible to determine whether these measures actually represent defensive medicine or if they represent different medical care that leads to fewer medical errors and adverse events.

Secondly, the main outcome in this study was whether a doctor was sued. The researchers did not explore whether increased spending was associated with fewer medical errors or fewer adverse events. In fact, previous work has shown considerable discrepancies between adverse events and malpractice claims.8

Thirdly, it would be interesting to know if doctors in the highest spending categories had been named in a malpractice claim before the study period. If, in fact, those in the highest spending categories had been sued before the study, they may be more acutely aware of the risk of malpractice claims and may be employing targeted defensive practice or other unobserved practices such as better patient communication consciously to reduce the risk.

These issues highlight the need for future research in this area. It may be tempting for doctors to use the results to justify ordering unnecessary tests and procedures to reduce their risk of malpractice claims. Instead, we should consider Jena and colleagues’ study as a contribution to our understanding of the risk of such claims. The study shows that we need to understand better defensive medicine, including how to define and reliably measure it and how this type of practice affects both patients and doctors. Future research should explore what specific tests and procedures doctors overuse mainly for defensive purposes and the effect this practice has not only on medical errors and adverse events but also on over-diagnosis and escalating costs.