Journal of Nursing Management, 2015
Association between shift work and severity of depressive symptoms among female nurses: the Korea Nurses’ Health Study HEA YOUNG LEE R N , P h D 1,2, MI SUN KIM HAN-KYOUL KIM M P H 2,4,8,9
MHA
2,3,4
, OKSOO KIM
RN, PhD
5,6
, IL-HYUN LEE
PhD
2,7
and
1
Professor, Department of Nursing, Doowon Technical University College, Gyeonggi-do, 2Researcher, the Korea Nurses’ Health Study, Seoul, 3PhD candidate, College of Public Health Science, Graduate School of Korea University, Seoul, 4Researcher, Research Institute of Health Policy, Korean Nurses Association, Seoul, 5President, Korean Nurses Association, Seoul, 6Professor, Division of Nursing, Ewha Womans University, Seoul, 7Senior Consultant, Stat Edu, Jeonju, 8PhD course student, College of Public Health Science, Graduate School of Korea University, Seoul, 9BK21 PLUS Program in ‘Embodiment: Health-Society Interaction’, Department of Public Health Sciences, Graduate School, Korea University, Seoul, Korea
Correspondence Mi Sun Kim Graduate School of Korea University, Hana Science Hall, Building B, Room no. 363, 5th Street, Anam-dong, Seongbuk-gu, Seoul, South Korea 136-713 E-mail: [email protected]
LEE H.Y., KIM M.S., KIM O., LEE I.-H. & KIM H.-K.
(2015) Journal of Nursing Management Association between shift work and severity of depressive symptoms among female nurses: the Korea Nurses’ Health Study Aim To determine the prevalence of depression and the relationship between shift work and depression severity among female nurses in South Korea. Background Shift work has been associated with higher risks of depressive symptoms, but there is a dearth of research on nurses, particularly investigating the severity of depressive symptoms. Methods Quantitative data including survey response from 9789 participants were analysed. Statistical analysis included descriptive, Spearman’s correlation and multivariable ordinal logistic regression. Results The numbers of nurses according to the severity of depressive symptoms were 35.2% (n = 3445), 38.0% (n = 3716), 16.1% (n = 1578), 7.6% (n = 747) and 3.1% (n = 303) for normal, mild, moderate, severely moderate and severe level of depressive symptoms, respectively. After adjusting for sociodemographic and health behavioural factors, nurses who worked shifts had 1.519-times greater odds of experiencing a higher severity of depressive symptoms (OR = 1.519, CI = 1.380–1.674, P < 0.001). Conclusion This study shows a higher prevalence of depressive symptoms among nurses who worked shifts and suggests that shift work may increase the severity of depressive symptoms among female nurses in South Korea. Implications for nursing management Nursing professionals, managers and health policy makers need to understand the factors influencing depressive symptoms and to use appropriate interventions based on the severity and not just the onset. Keywords: depressive symptoms, Korea Nurses’ Health Study, nurse, shift work
Accepted for publication: 16 February 2015
Introduction More than 500 million people of all ages are afflicted with depression globally (Ferrari et al. 2010). According to the Global Burden of Disease Study 2010, DOI: 10.1111/jonm.12298 ª 2015 John Wiley & Sons Ltd
depressive disorders were a leading cause of disability adjusted life years and a second leading cause of years lived with disability worldwide (Ferrari et al. 2013). Particularly, the burden of depression is 50% higher for women and is the leading cause of disability 1
H.-Y. Lee et al.
among women in both high-income and low-income countries today (Mathers et al. 2008). For women aged 15–44 years, mental disorders including depression are one of main causes of loss of healthy lives (Mathers et al. 2008). The prevalence of depression is also high and increasing in South Korea. The Korea National Health and Nutrition Examination Survey reports that the number of adults with depressive symptoms showed an 87.6% increase from 2980 (1241 male, 1739 female) in the year 2007 to 5590 (2309 male, 3281 female) in 2012 (Korea Centers for Disease Control and Prevention 2012). The prevalence of depression in South Korea is also higher among females than among males (Chun et al. 2006). Additionally, the 2010 Korean Work Environment Survey also reports that, out of 20 occupational categories, health-care workers were ranked third in terms of the prevalence of depressive symptoms in 2010 (Korean Statistical Information Service 2011). Compared with other healthcare professionals, nurses exhibit greater job stress (Sehlen et al. 2009). Nursing may carry a high risk of depression due to the perpetual care of individuals in distress and the burnout that can result from caring for sick patients (Poghosyan et al. 2009). One of the factors known to cause depression including the nursing profession is shift work (Saksvik et al. 2011). Shift work is known negatively to affect both physical and mental health (Zhao & Turner 2008, Zhao et al. 2011). The International Council of Nurses declared in 2007 that in order to provide 24hour care to patients, shift work is necessary. However, the potential benefit of flexible work schedules and higher pay does not protect nurses from occupational harm. In particular, depression among South Korean nurses is increasing (Yoon & Cho 2007, Kim & Kim 2011, Yoon & Kim 2013). Most studies on depression in nursing focused on nurses dealing with patients who are suffering from depression (Lamers et al. 2011, Adams et al. 2012, Haugan et al. 2013), not depression among nurses themselves. Additionally, compared with other occupations, a relative dearth of research was conducted on investigating the relationship between shift work and depression among nurses. Furthermore, most of the previous studies have dichotomised the prevalence of depression or depressive symptoms (Ardekani et al. 2008, Eldevik et al. 2013). Thus, the aim of this study is to understand the prevalence of depressive symptoms and the relationship between shift work and the severity of depressive symptoms among female nurses in South Korea. 2
Methods Study design and sample The Nurses’ Health Study (NHS), started in 1976 with funding from the National Institutes of Health in the USA, is one of the world’s largest and longest cohort studies to investigate factors influencing women’s health. Harvard University has been leading the NHS research in the field of women’s health with information provided by more than 238 000 nurses. The Korea Nurses’ Health Study (KNHS) is the South Korean version of the NHS. The KNHS used questionnaires from NHS 3 with funding from the Korea Centers for Disease Control and Prevention (KCDC) of the Korea National Institute of Health (KNIH). KNHS is a joint research project of the Korean Nurses Association (KNA) and KCDC, and it is a cooperative study with Harvard University. KNHS is funded for 3 years (phase 1) since January 2013 and will be reviewed by the KCDC for additional funding. The KNHS is a cohort study; the data used for the current study were from the baseline data. We had a multi-disciplinary advisory board with experts including academic researchers involved with the NHS at Harvard University and from academia in South Korea. The KNA sent the web-based survey to nurses in its nurse registry via e-mail. After sending the e-mails, the research team gave presentations in hospitals across South Korea and co-worked with hospitals on online advertising via the intranet of each hospital. Also, we sent reminder e-mails every month to all of the South Korean female registered nurses. We also mailed promotional posters and catalogues to be placed at each hospital. According to the 2013 National Health Insurance Statistical Yearbook, a total of 134 748 are active registered nurses (National Health Insurance Service & Health Insurance Review & Assessment Service 2014). For the current study, a total of 10 173 nurses voluntarily registered and completed the self-administered questionnaires between July and December 2013; of these nurses, 9789 were included in the analyses after excluding participants with missing data.
Measurement We translated and back-translated the questionnaires. The questionnaires used in the KNHS collected information on sociodemographic characteristics, comorbidities, medical history, family history of disease, reproductive health, lifestyle, psychiatric and occupational characteristics and health behaviours. In ª 2015 John Wiley & Sons Ltd Journal of Nursing Management
Shift work and severity of depression: the Korea NHS
this study, the variables of primary interest were shift work and the severity of depressive symptoms, along with various confounding variables. Shift work is defined as ‘any arrangement of daily working hours that differs from the standard daylight hours’ (Smith et al. 2003). Participants who worked on a regular daytime schedule were coded 0, and all others were coded 1. Traditional three 8-hour shifts are being used in South Korea. The KNHS participants were asked whether they worked in shifts. Depressive symptoms were measured via the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 is a self-report instrument to identify and measure the severity of depressive symptoms. The PHQ-9 contains nine items, and the total scores range from 0 (minimal depressive symptoms) to 27 (all symptoms occurring daily). Scores of 0–4, 5–9, 10–14, 15–19 and 20 or higher represent minimal, mild, moderate, moderately severe and severe depressive symptoms, respectively (Kroenke et al. 2001). The sensitivity and the specificity for the major depressive symptoms of a PHQ-9 score over 10 is 88% according to the original PHQ-9 paper (Kroenke et al. 2001). The Cronbach’s alpha reliability estimate in the present study was 0.90, which is similar to the Cronbach’s alpha reliability estimate of 0.87 in the original PHQ-9 study (Arroll et al. 2010). Based on the literature, sociodemographic characteristics including increasing age (Lamers et al. 2012), lower level of education (Jang et al. 2009, Mueller et al. 2010, Lamers et al. 2012), lower level of annual income (Mueller et al. 2010), never being married (Jang et al. 2009) as well as health behaviour factors including smoking (Boden et al. 2010), frequent alcohol consumption (Fergusson et al. 2009) and less physical activities (Teychenne et al. 2008) are all risk factors for depression. Confounding variables that were adjusted for were age (29 years or younger, 30– 39, 40 years or older), level of education (3-year college, 4-year college, Master’s degree or higher), annual income (
Association between shift work and severity of depressive symptoms among female nurses: the Korea Nurses’ Health Study HEA YOUNG LEE R N , P h D 1,2, MI SUN KIM HAN-KYOUL KIM M P H 2,4,8,9
MHA
2,3,4
, OKSOO KIM
RN, PhD
5,6
, IL-HYUN LEE
PhD
2,7
and
1
Professor, Department of Nursing, Doowon Technical University College, Gyeonggi-do, 2Researcher, the Korea Nurses’ Health Study, Seoul, 3PhD candidate, College of Public Health Science, Graduate School of Korea University, Seoul, 4Researcher, Research Institute of Health Policy, Korean Nurses Association, Seoul, 5President, Korean Nurses Association, Seoul, 6Professor, Division of Nursing, Ewha Womans University, Seoul, 7Senior Consultant, Stat Edu, Jeonju, 8PhD course student, College of Public Health Science, Graduate School of Korea University, Seoul, 9BK21 PLUS Program in ‘Embodiment: Health-Society Interaction’, Department of Public Health Sciences, Graduate School, Korea University, Seoul, Korea
Correspondence Mi Sun Kim Graduate School of Korea University, Hana Science Hall, Building B, Room no. 363, 5th Street, Anam-dong, Seongbuk-gu, Seoul, South Korea 136-713 E-mail: [email protected]
LEE H.Y., KIM M.S., KIM O., LEE I.-H. & KIM H.-K.
(2015) Journal of Nursing Management Association between shift work and severity of depressive symptoms among female nurses: the Korea Nurses’ Health Study Aim To determine the prevalence of depression and the relationship between shift work and depression severity among female nurses in South Korea. Background Shift work has been associated with higher risks of depressive symptoms, but there is a dearth of research on nurses, particularly investigating the severity of depressive symptoms. Methods Quantitative data including survey response from 9789 participants were analysed. Statistical analysis included descriptive, Spearman’s correlation and multivariable ordinal logistic regression. Results The numbers of nurses according to the severity of depressive symptoms were 35.2% (n = 3445), 38.0% (n = 3716), 16.1% (n = 1578), 7.6% (n = 747) and 3.1% (n = 303) for normal, mild, moderate, severely moderate and severe level of depressive symptoms, respectively. After adjusting for sociodemographic and health behavioural factors, nurses who worked shifts had 1.519-times greater odds of experiencing a higher severity of depressive symptoms (OR = 1.519, CI = 1.380–1.674, P < 0.001). Conclusion This study shows a higher prevalence of depressive symptoms among nurses who worked shifts and suggests that shift work may increase the severity of depressive symptoms among female nurses in South Korea. Implications for nursing management Nursing professionals, managers and health policy makers need to understand the factors influencing depressive symptoms and to use appropriate interventions based on the severity and not just the onset. Keywords: depressive symptoms, Korea Nurses’ Health Study, nurse, shift work
Accepted for publication: 16 February 2015
Introduction More than 500 million people of all ages are afflicted with depression globally (Ferrari et al. 2010). According to the Global Burden of Disease Study 2010, DOI: 10.1111/jonm.12298 ª 2015 John Wiley & Sons Ltd
depressive disorders were a leading cause of disability adjusted life years and a second leading cause of years lived with disability worldwide (Ferrari et al. 2013). Particularly, the burden of depression is 50% higher for women and is the leading cause of disability 1
H.-Y. Lee et al.
among women in both high-income and low-income countries today (Mathers et al. 2008). For women aged 15–44 years, mental disorders including depression are one of main causes of loss of healthy lives (Mathers et al. 2008). The prevalence of depression is also high and increasing in South Korea. The Korea National Health and Nutrition Examination Survey reports that the number of adults with depressive symptoms showed an 87.6% increase from 2980 (1241 male, 1739 female) in the year 2007 to 5590 (2309 male, 3281 female) in 2012 (Korea Centers for Disease Control and Prevention 2012). The prevalence of depression in South Korea is also higher among females than among males (Chun et al. 2006). Additionally, the 2010 Korean Work Environment Survey also reports that, out of 20 occupational categories, health-care workers were ranked third in terms of the prevalence of depressive symptoms in 2010 (Korean Statistical Information Service 2011). Compared with other healthcare professionals, nurses exhibit greater job stress (Sehlen et al. 2009). Nursing may carry a high risk of depression due to the perpetual care of individuals in distress and the burnout that can result from caring for sick patients (Poghosyan et al. 2009). One of the factors known to cause depression including the nursing profession is shift work (Saksvik et al. 2011). Shift work is known negatively to affect both physical and mental health (Zhao & Turner 2008, Zhao et al. 2011). The International Council of Nurses declared in 2007 that in order to provide 24hour care to patients, shift work is necessary. However, the potential benefit of flexible work schedules and higher pay does not protect nurses from occupational harm. In particular, depression among South Korean nurses is increasing (Yoon & Cho 2007, Kim & Kim 2011, Yoon & Kim 2013). Most studies on depression in nursing focused on nurses dealing with patients who are suffering from depression (Lamers et al. 2011, Adams et al. 2012, Haugan et al. 2013), not depression among nurses themselves. Additionally, compared with other occupations, a relative dearth of research was conducted on investigating the relationship between shift work and depression among nurses. Furthermore, most of the previous studies have dichotomised the prevalence of depression or depressive symptoms (Ardekani et al. 2008, Eldevik et al. 2013). Thus, the aim of this study is to understand the prevalence of depressive symptoms and the relationship between shift work and the severity of depressive symptoms among female nurses in South Korea. 2
Methods Study design and sample The Nurses’ Health Study (NHS), started in 1976 with funding from the National Institutes of Health in the USA, is one of the world’s largest and longest cohort studies to investigate factors influencing women’s health. Harvard University has been leading the NHS research in the field of women’s health with information provided by more than 238 000 nurses. The Korea Nurses’ Health Study (KNHS) is the South Korean version of the NHS. The KNHS used questionnaires from NHS 3 with funding from the Korea Centers for Disease Control and Prevention (KCDC) of the Korea National Institute of Health (KNIH). KNHS is a joint research project of the Korean Nurses Association (KNA) and KCDC, and it is a cooperative study with Harvard University. KNHS is funded for 3 years (phase 1) since January 2013 and will be reviewed by the KCDC for additional funding. The KNHS is a cohort study; the data used for the current study were from the baseline data. We had a multi-disciplinary advisory board with experts including academic researchers involved with the NHS at Harvard University and from academia in South Korea. The KNA sent the web-based survey to nurses in its nurse registry via e-mail. After sending the e-mails, the research team gave presentations in hospitals across South Korea and co-worked with hospitals on online advertising via the intranet of each hospital. Also, we sent reminder e-mails every month to all of the South Korean female registered nurses. We also mailed promotional posters and catalogues to be placed at each hospital. According to the 2013 National Health Insurance Statistical Yearbook, a total of 134 748 are active registered nurses (National Health Insurance Service & Health Insurance Review & Assessment Service 2014). For the current study, a total of 10 173 nurses voluntarily registered and completed the self-administered questionnaires between July and December 2013; of these nurses, 9789 were included in the analyses after excluding participants with missing data.
Measurement We translated and back-translated the questionnaires. The questionnaires used in the KNHS collected information on sociodemographic characteristics, comorbidities, medical history, family history of disease, reproductive health, lifestyle, psychiatric and occupational characteristics and health behaviours. In ª 2015 John Wiley & Sons Ltd Journal of Nursing Management
Shift work and severity of depression: the Korea NHS
this study, the variables of primary interest were shift work and the severity of depressive symptoms, along with various confounding variables. Shift work is defined as ‘any arrangement of daily working hours that differs from the standard daylight hours’ (Smith et al. 2003). Participants who worked on a regular daytime schedule were coded 0, and all others were coded 1. Traditional three 8-hour shifts are being used in South Korea. The KNHS participants were asked whether they worked in shifts. Depressive symptoms were measured via the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 is a self-report instrument to identify and measure the severity of depressive symptoms. The PHQ-9 contains nine items, and the total scores range from 0 (minimal depressive symptoms) to 27 (all symptoms occurring daily). Scores of 0–4, 5–9, 10–14, 15–19 and 20 or higher represent minimal, mild, moderate, moderately severe and severe depressive symptoms, respectively (Kroenke et al. 2001). The sensitivity and the specificity for the major depressive symptoms of a PHQ-9 score over 10 is 88% according to the original PHQ-9 paper (Kroenke et al. 2001). The Cronbach’s alpha reliability estimate in the present study was 0.90, which is similar to the Cronbach’s alpha reliability estimate of 0.87 in the original PHQ-9 study (Arroll et al. 2010). Based on the literature, sociodemographic characteristics including increasing age (Lamers et al. 2012), lower level of education (Jang et al. 2009, Mueller et al. 2010, Lamers et al. 2012), lower level of annual income (Mueller et al. 2010), never being married (Jang et al. 2009) as well as health behaviour factors including smoking (Boden et al. 2010), frequent alcohol consumption (Fergusson et al. 2009) and less physical activities (Teychenne et al. 2008) are all risk factors for depression. Confounding variables that were adjusted for were age (29 years or younger, 30– 39, 40 years or older), level of education (3-year college, 4-year college, Master’s degree or higher), annual income (
