Association between body mass index and burnout among nurses in China: a cross-sectional study

Abstract

Objectives

Body mass index (BMI) can affect an individual’s health. The night shift is a characteristic of the nursing profession, which is associated with an abnormal BMI. However, few studies have investigated the association between BMI and burnout in Chinese nurses. This study examined the association between BMI and burnout among Chinese nurses.

Methods

A total of 1863 nurses from 12 tertiary hospitals in Shandong Province of China were selected. BMI was calculated as body weight divided by height squared. The Maslach Burnout Service Inventory General Survey (MBI-GS) was used to measure the level of burnout among nurses. Ordinal logistic regression was used to analyse the association between BMI and burnout.

Results

In this study, the prevalence of normal BMI, underweight, overweight, and obesity was 69.2%, 7.5%, 18.2%, and 5.2%, respectively. The prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 26.1%, 38.7%, and 35.6%, respectively. Nurses who were obese were more likely to have high levels of emotional exhaustion (OR=1.493, 95% CI: 1.011 to 2.206) and cynicism (OR=1.511, 95% CI: 1.014 to 2.253), and nurses who were underweight were more likely to have high levels of cynicism (OR=1.593, 95% CI: 1.137 to 2.232) compared with those who were normal weight.

Conclusions

Obesity was positively associated with emotional exhaustion and cynicism, and being underweight was only positively associated with cynicism among Chinese nurses. Hospital administrators should consider BMI when taking effective measures to reduce burnout among nurses.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• As Shandong Province is a typical province in terms of population structure, social and cultural life of China, the sample was representative.

• This study had a large sample size and a high response rate.

• This study was based on self-reports of the respondents, which may have resulted in recall bias and errors.

• The results of this study cannot be generalised to be extended to nurses from primary and secondary hospitals.

Background

Nursing is among the most prone professions to burnout,¹ and the COVID-19 pandemic has increased the level of burnout of nurses.² Burnout refers to a psychological condition in which individuals react to interpersonal stressors at work³ and is often divided into three dimensions: emotional exhaustion, cynicism, and low personal accomplishment.⁴ Emotional exhaustion is the most obvious manifestation of burnout and includes loss of enthusiasm, frustration, stress, and fatigue. Cynicism refers to an individual who has a negative and sarcastic attitude and expresses indifference or detachment from his or her work. Low personal accomplishment refers to dissatisfaction with one’s work achievements and a feeling that the work is not valuable. Previous studies found that 78% of Swedish nurses, 34% of American nurses⁵, and 50% of Chinese nurses experience burnout.⁶ The percentages of Spanish nurses with high levels of emotional exhaustion, cynicism, and personal accomplishment were 25%, 30%, and 30%, respectively.¹ A high level of burnout can decrease quality of life and increase the risk of suicide among nurses.⁷ Furthermore, burnout negatively affects patient care quality. For example, it can lead to more sick days, absenteeism, and medical errors among nurses, and reduced productivity.⁸ Therefore, burnout among nurses has become an important issue that needs to be addressed urgently.

In recent decades, the number of obese people has exceeded the number of underweight people, and the world has entered an era in which more people are obese than underweight.⁹ Previous studies have found that nurses are more likely to be overweight or obese.^{10 11} A Scottish study found that 69.1% of nurses were overweight or obese.¹² Another previous study found that 30.6% of nurses in the USA were obese.¹³ Both stress and night shifts are occupational characteristics of nursing. Work-related stress can affect behaviour by inducing overeating and consumption of foods in high calories, fat or sugar, reducing physical activity, and reducing sleep time. In addition, stress can trigger physiological changes on the hypothalamic–pituitary–adrenal axis, reward processing in the brain and possibly in the gut microbiome.¹⁴ Night shift work has also been found to be associated with poor sleep, which increases appetite and unhealthy snacking.^{11 15} Increased body weight negatively affects the health of individuals, increasing the risk of high blood pressure, heart disease, and type 2 diabetes.¹⁶

Although previous studies have investigated the association between body mass index (BMI) and burnout among healthy employees, the results are still inconclusive, and few studies have investigated the association between BMI and burnout among nurses. One study found a negative association between obesity and burnout levels,¹⁷ while another found a positive association between them.¹⁸ Furthermore, previous studies that focused on the association between BMI and burnout often used vital exhaustion presented with burnout and ignored the two dimensions of burnout (cynicism and low personal accomplishment).^{19 20} Additionally, most studies have focused on the prevalence of overweight and obesity among nurses,^{13 21} and the prevalence of underweight among nurses has been ignored. However, underweight also has negative effects on individual health,²² which may lead to a high level of burnout. Based on the literature review, this study aimed to examine the association between BMI and burnout among Chinese nurses. The results of this study provide novel suggestions for hospital administrators to reduce the prevalence of burnout among nurses.

Methods

Study design and sample

This cross-sectional survey was conducted in Shandong Province, China, between 30 July and 30 September 2020. This survey used the multistage stratified random sampling method. First, according to the 2019 gross domestic product (GDP) per capita, 16 cities at the prefecture-level in Shandong Province were divided into three groups: high (GDP per capita >100 000 Chinese yuan), medium (GDP per capita of 50 000–100 000 Chinese yuan) and low (GDP per capita <50 000 Chinese yuan), and in each group, two prefecture-level cities are randomly selected. Then, two tertiary hospitals were randomly selected in each sampled city. Categorised according to internal medicine, surgery, obstetrics and gynaecology, paediatrics, emergency and other departments (excluding administrative departments), two-thirds or more departments in each category were randomly selected in each hospital and a random questionnaire survey was conducted among nurses in the selected departments.²³ The questionnaire for this study was an electronic questionnaire created through ‘Questionnaire.com’ (https://www.wenjuan.com). The electronic questionnaire was sent to the participants’ cell phones using WeChat.²³ In total, 1933 nurses from 12 tertiary hospitals in six cities were invited to participate in this survey. After excluding 70 participants for missing data, 1863 responses were finally included in the analysis. The response rate was 96.38%.

Measurement

Burnout

In this study, the Chinese version of the 15-item Maslach Burnout Service Inventory-General Survey (MBI-GS)²⁴ was used to measure the level of burnout among nurses, which has been validated among Chinese nurses.²⁵ The MBI-GS includes three dimensions: emotional exhaustion (five items), cynicism (four items), and personal accomplishment (six items). Each question was answered using a 7-point Likert scale (ranging from 0= ‘never’ to 6= ‘every day’). The cut-off points for the Chinese version of the MBI-GS are as follows: emotional exhaustion (low: <11; moderate: 11–14; high: ≥15), cynicism (low: <5; medium: 5–7; high: ≥8) and personal accomplishment (low: ≥30; medium: 26–29; high: <26).²⁶ In the current survey, Cronbach’s alpha coefficient for the MBI-GS scale was 0.807 and Cronbach’s alpha coefficients for emotional exhaustion, cynicism, and personal accomplishment were 0.940, 0.939, and 0.930, respectively.

Body mass index

BMI scores were calculated as body weight (kg) divided by height in metres square (m²).²⁷ Based on the criteria of WHO, the participants were categorised as underweight (<18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25.0–29.9 kg/m²) or obese (≥30.0 kg/m²).^{10 28 29}

Covariates

The basic characteristics of the nurses in this study included age, sex, marital status (married or single), and education (junior college and below, bachelor’s degree, and master’s degree and above). The job characteristics included departments (internal medicine, surgery, obstetrics and gynaecology, paediatrics, emergency department, and other departments), title (primary, intermediate, and senior), establishment (formal or contract) and the number of night shifts per week (0, 1–2, ≥3). Participants were asked how many children they have, and divided into three groups according to their answer (0, 1, ≥2).

Statistical analysis

This study used IBM SPSS V.20.0 statistical package to analyse the data. Categorical variables were described as percentages. The Kruskal-Wallis test was used to compare the distribution of BMI categorization in different burnout dimensions. Ordered logistic regression was used to analyse the relationship between BMI and burnout. Statistical significance was set at p<0.05.

Patient and public involvement

Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

Results

Sample characteristics

Table 1 presents the demographic characteristics of the participants. Of the 1863 participating nurses, 93.8% were women and 79.9% were married. More than half of the nurses were in the 31–50 age group (63.3%) and had a bachelor’s degree (88.0%). Of the participants, 39.1% were from the surgery departments. A total of 48.1% had an intermediate title. Furthermore, 78.4% were contract employees and 75.3% had at least one child. Lastly, 96.5% had at least one night shift per week and 69.2% had a normal BMI. The prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 26.1%, 38.7%, and 35.6%, respectively.

Table 1.

Demographic characteristics of participants (N=1863)

Variables	Group	N	%
Sex	Male	115	6.2
	Female	1748	93.8
Age	≤30	610	32.7
	31–50	1180	63.3
	>50	73	3.9
Marital status	Single	375	20.1
	Married	1488	79.9
Educational level	Junior college or less	135	7.2
	Bachelor	1639	88.0
	Master or above	89	4.8
Department	Internal medicine	524	28.1
	Surgery	729	39.1
	Obstetrics and gynaecology	95	5.1
	Paediatrics	134	7.2
	Emergency department	164	8.8
	Other	217	11.6
Professional title	Primary	886	47.6
	Intermediate	896	48.1
	Senior	81	4.3
Employment status	Formal	402	21.6
	Contract	1461	78.4
Number of children	None	462	24.8
	1	884	47.5
	≥2	517	27.7
Night shifts per week	None	65	3.5
	1–2	1636	87.8
	≥3	163	8.7
BMI	Normal	1289	69.2
	Underweight	140	7.5
	Overweight	339	18.2
	Obesity	96	5.2
Emotional exhaustion	Low	891	47.8
	Medium	486	26.1
	High	487	26.1
Cynicism	Low	778	41.7
	Medium	378	20.3
	High	708	38.7
Personal accomplishment	Low	663	35.6
	Medium	188	10.1
	High	1013	54.3

BMI, body mass index.

The levels of burnout and the categories of BMI among nurses

Table 2 shows the levels of burnout and BMI categories among nurses. In the normal group, the prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 25.1%, 37.0%, and 36.0%, respectively. In the underweight group, the prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 29.3%, 48.6%, and 27.9%, respectively. In the overweight group, the prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 25.4%, 35.1%, and 37.8%, respectively. Finally, in the obese group, the prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 37.9%, 46.3%, and 32.6%, respectively. The distribution of cynicism differed significantly between the four categories of BMI (p<0.05).

Table 2.

Distribution of burnout levels according to BMI categories

Variable	BMI				H	P
	Normal	Underweight	Overweight	Obesity
Emotional exhaustion, n (%)					5.081	0.166
Low	618 (47.9)	63 (45.0)	170 (50.1)	39 (41.1)
Medium	347 (26.9)	36 (25.7)	83 (24.5)	20 (21.1)
High	324 (25.1)	41 (29.3)	86 (25.4)	36 (37.9)
Cynicism, n (%)					9.179	0.027
Low	553 (42.9)	49 (35.0)	143 (42.2)	32 (33.7)
Medium	259 (20.1)	23 (16.4)	77 (22.7)	19 (20.0)
High	477 (37.0)	68 (48.6)	119 (35.1)	44 (46.3)
Personal accomplishment, n (%)					7.698	0.053
Low	464 (36.0)	39 (27.9)	128 (37.8)	31 (32.6)
Medium	127 (9.9)	10 (7.1)	41 (12.1)	10 (10.5)
High	698 (54.2)	91 (65.0)	170 (50.1)	54 (56.8)

H-values are derived from Kruskal-Wallis Test; Significant P-values are in bold.

BMI, body mass index.

Ordinal logistic regression analysis of BMI and emotional exhaustion, cynicism, and personal accomplishment

Table 3 shows the results of the ordinal logistic regression analysis of BMI and emotional exhaustion, cynicism, and personal accomplishment (see online supplemental tables S1–S3). After adjusting for all covariates, Model 1 showed that compared with normal BMI, obesity (OR=1.493, 95% CI: 1.011 to 2.206) was positively associated with a higher level of emotional exhaustion. Model 2 showed that, compared with normal BMI, both obesity (OR=1.511, 95% CI: 1.014 to 2.253), and underweight (OR=1.593, 95% CI: 1.137 to 2.232) were positively associated with a higher level of cynicism. There was no association between BMI and personal accomplishment.

Table 3.

Output of ordinal logistic regression analysis of association between BMI and emotional exhaustion, cynicism, personal accomplishment

Variable	B	SE	P value	OR	95% CI
Model 1 (Emotional exhaustion)
BMI
Normal (ref.)
Obesity	0.401	0.199	0.044	1.493	1.011 to 2.206
Underweight	0.183	0.170	0.280	1.201	0.861 to 1.675
Overweight	−0.050	0.118	0.670	0.951	0.755 to 1.198
Model 2 (cynicism)
BMI
Normal (ref.)
Obesity	0.413	0.204	0.043	1.511	1.014 to 2.253
Underweight	0.465	0.172	0.007	1.593	1.137 to 2.232
Overweight	−0.036	0.117	0.756	0.964	0.766 to 1.213
Model 3 (personal accomplishment)
BMI
Normal (ref.)
Obesity	0.078	0.214	0.714	1.081	0.711 to 1.644
Underweight	0.269	0.187	0.150	1.309	0.907 to 1.888
Overweight	−0.072	0.122	0.557	0.931	0.732 to 1.183

Models 1–3 adjusted for age, sex, marital status, educational level, department, professional status, employment status, night shifts per week, and number of child.

Significant P-values are in bold.

B, the coefficients; BMI, body mass index.

Discussion

This is the first study to investigate the association between BMI and three dimensions of burnout (emotional exhaustion, cynicism, and personal accomplishment) among Chinese nurses. The findings of this study provide a reference for hospital administrators to reduce nurses’ levels of burnout and maintain their health.

Burnout among nurses is a global issue. A review revealed that the prevalence of emotional exhaustion was 34.1%, cynicism was 12.6%, and lack of personal accomplishment was 15.2%.² In this study, the prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 26.1%, 38.7%, and 35.6%, respectively. These findings suggest that Chinese nurses have a higher prevalence of high levels of cynicism and a reduced sense of personal accomplishment, which should receive more attention from hospital administrators.

In this study, the prevalence rates of overweight and obesity were 18.2% and 5.2%, respectively. Previous studies have shown that the prevalence of overweight among nurses in the USA and Lebanon was 30.6%¹³ and 31.6%,³⁰ respectively, and the prevalence of obesity among nurses in the USA and Poland was 23.6%¹³ and 11.2%,²¹ respectively. Compared with nurses in these countries, Chinese nurses have a lower prevalence of overweight and obesity. As the BMI of the global population, including the Chinese population, has been showing an increasing trend in recent years, most studies have focused on obesity or overweight in nurses,¹⁵ but neglected the prevalence of underweight among nurses. However, being underweight also has negative effects on the health of individuals.⁹ In this study, we found that 7.5% of Chinese nurses were underweight, which was higher than that of Polish nurses (1.2%)²¹ and similar to the rate among Chinese women in rural areas in 2014 (7.8%).³¹ Therefore, the prevalence of underweight among Chinese nurses should attract the attention of hospital administrators.

Our data showed that obesity was positively associated with emotional exhaustion among Chinese nurses, indicating that obese nurses were more likely to experience a higher level of emotional exhaustion than those of normal weight. An explanation for this phenomenon is that most obese people often experience fatigue.³² Fat increases the burden on motor organs, bones, joints, and muscles, and the large amount of fat around the joints restricts the movement of the joints.³³ In addition, obese people are prone to snoring while sleeping,³⁴ leading to poor sleep quality and sleep apnoea syndrome, which aggravates brain hypoxia.³⁵ The process of energy consumption in the absence of oxygen easily produces lactic acid to make people feel tired. Nursing work is complex and requires a lot of physical effort; thus, obese nurses are more likely to feel fatigued at work, leading to reduced enthusiasm for work. Another explanation is that obese people have a higher risk of depression,³⁶ which is an important determinant of emotional exhaustion.³⁷

In this study, obesity was positively associated with cynicism among Chinese nurses, which means that obese nurses were more likely to experience a higher level of cynicism than nurses of normal weight. The stigma associated with obesity may explain this finding. The stigma of obesity has been frequently reported by employers, teachers, physicians, and nurses.³⁸ A systematic review found that weight stigma is associated with adverse physiological and psychological outcomes,^{39 40} leading to a decrease in enthusiasm for work among nurses. Additionally, in China, good image and etiquette are professional requirements for nurses because the image of nurses can affect the nurse–patient relationship and the quality of nursing services.⁴¹ Obese nurses may lack confidence to build good nurse–patient relationships or provide good care. As a result, they might be more likely to distance themselves from patients and adopt an indifferent, neglectful attitude toward patients, which could increase their level of cynicism.

Our data also demonstrated that underweight nurses were more likely to exhibit higher levels of cynicism than those with normal weight. Previous studies have found that underweight individuals indicated poorer self-rated health²² and a higher risk of mortality.⁴² As nursing has a stressful workload, nurses with poor self-rated health may be inactive in their work, or they may apply for a transfer to other positions with less workload to maintain good health status. Therefore, they may have a distant attitude towards nursing work and a high level of cynicism.

This study has some limitations. First, as this was a cross-sectional study, the causal relationship between BMI and burnout could not be determined, and future longitudinal studies should be conducted to determine the causal relationship. Second, the survey in this study was based on the self-reports of respondents, which may have resulted in recall bias and errors. Third, because the respondents in this study were from tertiary hospitals, the findings of this study cannot be generalized to primary and secondary hospitals.

Conclusion

To conclude, we found that obesity was positively associated with emotional exhaustion and cynicism and that underweight was only positively associated with cynicism among Chinese nurses. Hospital administrators should take into account both the prevalence of obesity and underweight among nurses, and should consider them when taking effective measures to reduce the level of burnout among nurses.

Implications

The findings of this study have some policy implications for hospital administrators. First, because both obesity and underweight have negative effects on nurses’ health, health education courses should be conducted in hospitals to promote dietary nutrition and healthy behaviours to avoid obesity or underweight in nurses. Second, previous studies found that night shift nurses have irregular meal times and a preference for high-calorie foods.^{30 43} Therefore, we suggest that hospitals should reasonably arrange the meal times of night shift nurses and provide them with healthy food alternatives. Third, hospital administrators should take effective measures to eliminate weight bias and stigma toward nurses.

Data availability statement

Data are available upon reasonable request.

Ethics statements

Patient consent for publication

Not applicable.

Ethics approval

This study involves human participants and was approved by The research was approved by the Ethical Review Committee of the School of Nursing and Rehabilitation, Shandong University (Approval number: 2020-R-50). All subjects gave their informed consent for inclusion before participating in the survey. Participants gave informed consent to participate in the study before taking part.