A retrospective observational study analyzing work and study motivation based on the work environment of 15,677 Japanese clinicians in 2016

Physicians play an active role in public health. However, there is a limit to the knowledge and experience that can be gained through hospital work alone. This was a secondary data analysis from 100,000 doctors in Japan (15,677 respondents). The results of the analysis showed that 898 (8.4%) male and 190 (6.0%) female doctors worked 60 h or more in a week. The percentage of physicians whose spouse was a physician was found to be 31.4% (male) and 61.7% (female) (p < 0.001), and the rate of full-time working clinicians was 85.7% (male) and 30.0% (female) (p < 0.001). In the univariate analysis, female’s working hours were affected by childbirth and childcare experience (p < 0.001, 95% CI − 10.3 to − 8.4, with “none” as reference) and specialty certification (p < 0.001, 95% CI − 3.5 to − 1.4, with “none” as reference). In the multivariate analysis, physician’s working hours were associated with sex (coefficient, − 7.4; 95% CI − 8.3 to − 6.5, with “male as reference), childbirth/childcare (coefficient, − 2.2; 95% CI − 2.9 to − 1.4, with “possession” as reference), and specialty qualification (coefficient − 4.0, 95% CI − 5.0 to − 3.0, with “possession” as reference). To summarize the results of the analysis, work/study motivation of physicians will be facilitated by ensuring adequate learning opportunities and by developing support systems and environments.


Survey details of the physicians' work style survey in 2016.
First, the physician survey questionnaire covered the following four parts. The first part was composed of the physician's attributes include the attributes asked for included: age; sex; university of origin; year of graduation; place of residence; place of birth; type of work; income; family members living together; department; specialist qualification; childbirth, childcare experience, and leave of absence due to that; and affiliation with university medical office. This item was used to extract detailed attributes to obtain an accurate picture of the current status of physicians' work styles and working conditions. The second part contained working conditions in a time schedule-study mean. To investigate the working conditions of doctors, we asked them to describe their working conditions in a timetable. The subjects described their actual work, especially during the week from Thursday, December 8 to Wednesday, December 14. Respondents had the option of choosing either "workday" or "holiday". If they chose "holiday", there were no responses in the table for that day. Working hours were classified into four categories: "clinical office hours", "non-clinical office hours", "on-call hours", and "break time". For the definition of terms, clinical office hours were defined as the time spent in outpatient, inpatient, and home nursing care. Non-clinical office hours were defined as time dedicated to teaching, research, self-training, meetings, and administrative duties. On-call hours were defined as the time when the physician maintains a cell phone for contact from nighttime to the next morning and treats patients when the need for medical care arises. Finally, break time was defined as time allocated for meals and resting. The third part was composed of work shared with other professions or physicians, which included work that other professionals could perform on their behalf as follows: (1) explaining procedures to patients and obtaining consent, (2) taking vital parameters and obtaining data, (3) preparing medical records, (4) medical administration, and (5) moving and transporting patients. In reality, physicians may spend a lot of time performing these tasks on their own. Therefore, to enable work sharing with other professionals, physicians were asked to indicate the actual time spent on these tasks and the percentage of time that could be shared with other professionals. These included career awareness and future work style (clinician, general practitioner, nursing care and welfare field, occupational health, administrative position, private company, research, international health, etc.). The intent of these questions was to investigate physicians' intentions regarding career development and job diversity. The fourth part included intentions and years of working in the local area. We defined urban and metropolitan areas as cities like Tokyo, government-designated cities, and places where prefectural governments are located. Other cities and towns were classified as rural areas. The medical facility questionnaire survey covered the following four parts. The first part contained attributes of the medical facility: type of establishment, type of facility, type of hospital, number of inpatients, and number of outpatients. The second part included the number of staff members working at the facility. The third part contained questions in balancing work and family, measures instated by the institution to ensure that support, and availability of support for doctors to balance work and family life at each facility. The number of doctors that took childcare leave was assessed. Questions on the availability of day-care centers were also asked, their opening hours, and their working days.

Analysis.
To create a database for the analysis, we matched the questionnaires for physicians and facilities using the zip code. First, we extracted all generations of doctors whose zip codes matched those of the questionnaires for doctors and medical facilities. While the basic attributes of young doctors were the crux of the discussion on lifelong career development, this study aimed to analyze the factors necessary for career development from a survey on the working styles of young doctors (men and women under 40 years of age). The chi-square test was used to analyze the differences of attributes between male and female. Secondly, to grasp the relationship between the work attributes of young doctors and the working hours of the elderly (greater than 40), the distribution of working hours by sex and age is shown as a bar graph (Fig. 1 www.nature.com/scientificreports/ and mean values for clinical office hours, non-clinical office hours, on-call hours, and career aspirations by sex and age (Table 2). To find factors affecting physicians' working hours, we performed a univariate analysis. First, the univariate analysis showed that age, sex, department, childbirth/childcare experience, and specialty status were significantly associated with working hours. Secondly, we attempted to construct a multivariate model. However, spousal work status and number of hospital beds could not be entered as explanatory variables due to many missing values. Therefore, we conducted a multivariate analysis using age, sex, medical department, childbirth/childcare, and whether the patient obtained a medical specialty, which were significant in the univariate analysis. The results of the multivariate regression for each type of working hours (i.e., clinical office hours, non-clinical office hours, and on-call hours) are shown in Table 3. As an appendix analysis, we analyzed efforts to continue working without leaving the job during childbirth or childcare, depending on whether the respondent has experienced childbirth or childcare (the results by sex are attached as a supplemental file). All analyses were performed using Stata/IC version 15.0 (Stata Corp, College Station, TX, USA). p-values < 0.05 were considered statistically significant.
Ethics. This study was approved by the Ethics Committee of the Institute of Medical Science, University of Tokyo (approval number: 2020-33) and by the Ethics Committee of Fukushima Medical University (approval number: General 2020-166).
Informed consent was obtained from all the participants in the study in the form of the opt-out methods.

Results
The overall response rate generally reflects the age distribution of the physicians. www.nature.com/scientificreports/ These data are the accurate reflection of the overall employment situation of physicians in Japan. Therefore, from the attributes of physicians of all ages, we can extract the working styles and environment surrounding their employment. Consequently, we were able to clearly describe the differences in career development by sex.
We cross-referenced the physician questionnaire with the medical facility questionnaire based on their zip codes and selected 12,293 physicians. We sampled physicians under the age of 40 to describe the work styles of younger physicians and the environment surrounding their employment. The results showed that a total of 5094 (41.4%) were under 40 years (3295 males, 64.7%; 1799 females, 35.3%). Table 1 shows the basic demographics of the younger generation of physicians aged < 40 years. The number of valid responses varied by item. A total of 695 respondents provided their spouses' occupations. A total of 282 respondents had partners who were doctors (153 males, 31.4%; and 129 females, 61.7%; respectively p < 0.001), with a statistically significant difference. Additionally, 318 respondents (144 males, 30.0%; and 174 females, 85.7%) had spouses who worked full time, and the difference was statistically significant (p < 0.001).
Given the differences in the attributes of young doctors, we summarized the distribution of working hours for all generations in the figures. Figure 1a shows the distribution of weekly working hours by sex (n = 13,909). The most frequent response was "41-50 h" (n = 3743 [26.9%]), with a difference between males and females of 2939 [27.4%] and 823 [25.9%], respectively (p < 0.05). A total of 898 (8.4%) males and 190 (6.0%) females were overworked for more than 60 h, while 108 males (1.0%) and 18 females (0.5%) (n = 135, 10.0%) worked more than 81 h per week. Figure 1b showed the distribution of age and working hours (n = 14,142). The highest frequency was 31-40 working hours (n = 3803); Regarding overworking, 1116 people (29.3%) worked ≥ 60 h and 128 people (3.4%) worked ≥ 81 h (2.3%). Table 2 summarized the details of clinical office hours and on-call hours (n = 15,337; 11,762 males, 76.7%; 3575 females, 23.3%). The overall median clinical office hours was 40 (range, 0.5-119) hours, 41 (range, 0.5-119) for males and 37.5 (range, 2-107) for females. There was no clear difference in the time spent on miscellaneous duties between age and sex. As for future career preferences, there was a shift from clinical to private practice. There was no significant difference in the desire to increase or decrease workload between the age or sex groups.
In Table 5, we showed the efforts to work without turnover. The total number of valid responses was 4800 (2265 and 2535 in the groups with and without childcare experience, respectively), consisting of 12 items including reduced overtime work (466 vs. 417, p < 0.05), leave after shift change (187 vs. 280, p < 0.05), vacation promotion (269 vs. 184, p < 0.001), and creation of a system to prevent career delays (82 vs. 137 p < 0.05). There was a significant statistical difference between the two groups.

Discussion
This study showed that physician consultation times decreased with age for both male and female ( Table 2). In Japan, working hours tend to decrease in other occupations, regardless of the type of work 16 ; however, they are still high for doctors 17 . We have presented the working hours of Japanese physicians. In many countries around the world, it is common for physicians, excluding residents, to work longer hours 10,11 . In Western countries, there are regulations regarding maximum working hours for residents. However, there are no regulations regarding working hours for physicians. In Europe and the United States, the problem of doctors (including residents) working long hours became apparent from the 1990s to the 2000s 18,19 . As a result, the working hours were regulated. In Japan, guidelines on working hours for physicians are scheduled to be issued in 2024, more than 20 years later than that in Western countries. However, the current United States study showed that treatment outcomes do not change, regardless of whether residents' working hours are restricted or not 20,21 . Long working hours are an important factor to be considered under labor management because they can lead to burnout and a decline in job performance due to fatigue and lack of concentration [22][23][24][25][26] . While working hours are necessary for self-improvement as part of professional training, too long working hours leave little time for off-job training 27 . The prevalence of burnout among physicians is high globally, and it is important to prevent it. In particular, burnout is strongly associated with a decrease in physicians' motivation to work and learn. As a result, burnout syndrome reduces physicians' work and study time, which has a negative impact on patients' life expectancy. Therefore, more research should be conducted worldwide in the future not only on physician labor, but also on professional demotivation, depression, and burnout.
The present study showed that female physicians worked shorter hours than their male counterparts. This can be attributed to the fact that their partners were doctors (619 women, 63.9% vs. 598 men, 26 www.nature.com/scientificreports/ and that they were working full time (1334 women, 74.7% vs. 2629 men, 80.8%), as shown in Table 1. In previous studies [27][28][29][30] , working hours were thought to be affected only by childbirth and childcare experience, however, this study proved that they were greatly affected by the occupation and working style of their partner. To support the generation with childcare experience, it is socially important to create a system that allows them to continue working without leaving the workforce. Table 5 shows that there was a significant statistical difference in the intention to continue working without leaving the workforce between those who had experienced childcare and those who had not. There was a significant difference between the two groups.
Therefore, we believe that clarifying the difference in intentions between the two groups can serve as a basis for the development of social systems. Buddenberg et al. 31 reported that females become less career-oriented and more part-time oriented after raising children. To date, no study has reportedly compared the intentions of female physicians with and without childcare experience 32,33 . Globally, the percentage of female physicians is increasing yearly 34 . As a result, there is a need to improve the social infrastructure to support them. The goal is that society should work together to ensure that female doctors do not perceive childbirth and childcare as having a negative impact on their career development. In other words, the realization of the Sustainable Development Goals in the medical field is synonymous with comprehensive support for working female doctors [35][36][37] .
Multiple regression analysis revealed that physicians' working hours are associated with age, sex, department, childbirth/childcare experience, and specialist qualifications. Particularly, working hours generally decreased as age increased for both males and females. It is noteworthy that for men, working hours became longer with the acquisition of a medical specialty. Meanwhile, childbirth and childcare were found to shorten working hours for females. In Tables 3 and 4, we highlighted these two points. Childbirth and childcare experience and the availability of specialist qualifications had an impact on the working hours of female doctors. Working hours are an integral part of building a career. The skills required of a physician are not limited to hospital care but include the ability to think comprehensively about patients and their families and to provide them with the best options. The meaning encompassed by career in this paper is a broad concept that includes specialty medicine, obtaining a doctoral degree, and raising a family. Meanwhile, intermittent study and extensive case experiences are essential to acquire the broad cultivation required of physicians.
This study has some limitations. First, this was a cross-sectional study conducted at one point in time during the winter of 2016. This may result in seasonality in the physicians' working hours and work content. As a result, it may not reflect the standard work content throughout the year. Secondly, although the questionnaire was distributed in advance, recall bias may have occurred when respondents filled it out. Third, this survey was conducted in Japan in 2016. Therefore, the working environment for physicians may differ from current working conditions. The regional distribution of physicians and the ratio of men to women have changed due to changes in the social situation in Japan and the changes that have occurred as a result of these changes. In addition, the special situation of the coronavirus pandemic has been added, and the working environment may differ from that of physicians under normal social activities. The working environment during this pandemic has a significant impact not only on the physical situation of physicians, but also on their mental health 38 . Changes in the www.nature.com/scientificreports/  www.nature.com/scientificreports/ working environment have a significant impact on physicians' willingness to work, and as a result, their working conditions are changing as of 2022. Fourth, as the target population has become older, their working conditions, family environment, and career aspirations may differ from those of the same age today.