The physician's explanation to the patient and the patient's understanding of that explanation in the medical setting have become increasingly important in recent years. It has been reported that the physician's explanation and the level of the patient's understanding are related to patient satisfaction, patient treatment adherence, and treatment outcome [1–3]. Furthermore, it has been shown in recent years that inappropriate explanations by physicians can lead to medical disputes [4–9]. Thus, the physician's explanatory behaviour plays an important role in improving patient satisfaction, preventing medical disputes, and increasing treatment effectiveness.
The purposes of the physician's explanation are to obtain the patient's consent in cases of invasive care, to secure the patient's right of self-determination, to explain factors related to negative outcomes in patient care, and to give medical treatment guidance . Legally, the physician's duty to explain is derived from the doctrine of informed consent and the physician's duty of disclosure. Thus, because the physician's explanation to the patient is legally required, an inappropriate or inadequate explanation is a breach of the duty of disclosure.
According to our survey on medical malpractice litigation in recent years in Japan, cases focusing on the physician's explanation to the patient have increased in number. When the physician delivers an insufficient explanation to the patient, the physician is deemed to have delivered substandard care, even if there is no fault with respect to his/her medical judgment or manual skills. This is because an insufficient explanation by a physician means a failure to fulfil the physician's duty derived from the medical contract between the physician and patient.
As a matter of course, relevant criteria for the level of a physician's explanation have become an issue. The first criterion is that the explanation should be as comprehensive as a typical doctor would provide in a similar situation (the "rational doctor criterion theory") [11–13]. The second criterion is that the doctor explains as much as the patient wants (the "concrete patient criterion theory") [11–13]. A third criterion consists of the first and second criteria in combination: the explanation is what a typical doctor would provide and as much as the patient wants to know.
Although these criteria may be useful in evaluating whether a physician's explanation to a patient is appropriate, they are still too abstract for practicing physicians. In fact, the abstract criteria concerning physicians' explanations to patients are likely not useful to health professionals engaged in medical practice. To date, no findings have addressed the specific physician explanatory behaviours by which possible breaches of the duty of disclosure can be evaluated in actual medical settings.
The number of medical malpractice claims has increased since the latter half of the 1990s in Japan, and this trend is partially due to breaches of the physician's duty of disclosure . As noted, findings related to physicians' explanatory behaviours are extremely limited in Japan. Because decisions in litigated medical malpractice cases provide useful information about patient-physician interactions, we have analysed litigated medical malpractice cases in Japan [15–17]. We have examined the association between physicians' explanatory behaviours and physicians' legal liability, and have identified relationships between the specific manner of listening or talking to patients/families and decisions of negligent care . However, several problems remain with respect to these findings. First, the decided cases analysed in those studies were not necessarily cases where the pivotal issue was the physician's duty of disclosure. Second, variables related to patient-physician interactions were extremely limited in number. Third, the number of decided medical litigation cases was not large enough to provide unbiased findings.
The present study takes the above issues into consideration and differs from our previous research as follows . First, we have increased the number of decided medical malpractice cases in Japan where the main issue was the physician's duty to explain to the patient, by extending the time period in which decisions in medical litigation cases were made. Second, we have added more potential variables related to physicians' explanatory behaviours to make the selection of variables as comprehensive as possible. Examples of added variables include the number of times that the physician was present and whether consent was given by the patient or family.
Third, to identify predictors of physician behaviour regarding breach of the duty to explain, we have analysed of the patient and physician factors related to the physician's explanatory behaviour.
Using our dataset, we identified specific physician explanatory behaviours that may be related to the physicians' legal liability. Our findings may be useful for improving physicians' explanations to patients in medical settings.