Factors associated with depression of the parents who lost their only child in western China city

Background : The number of families who lost their only child is estimated to be 10 million by 2035. The parents who lost their only child are forced to endure psychological suffering and cope with elderly care problems alone. Long-term poor mental health can affect physical health and reduce the quality of life and well-being. Methods : 130 participants were selected using the method of combining stratified sampling with cluster sampling. The study used Geriatric Depression Scale (GDS) and adopted a generalized linear regression model to investigate the parents who lost their only child in Anshun city, Guizhou province, China, to comprehensively and systematically explore the depression status and it's influencing factors of the parents. Results : The parents who lost their only child of different self-rated health status ( P =0.004) and the number of chronic diseases ( P =0.001) had different GDS scores. European quality of life-5 dimensions (EQ-5D) score( P =0.019) and Social Support Rating Scale (SSRS) score ( P <0.001) were significantly associated with the depression of the parents who lost their only child. Conclusion : The parents who lost their only child is a high-risk group of depression, and targeted interventions should be carried out for them. The family doctor team should increase the frequency and content of serving them, and promptly manage their health. A diverse social support system should be built and consolidated for these parents.


Background
The one-child policy had been practiced for more than 30 years in China before it was ended in 2015. It required that each family could only have one child. Although the practice of the one-family-one-child policy had been successful in controlling the rapid growth of the population in China, it has brought new problems and challenges to the Chinese government and citizens, including the emergence of the families who lost their 3 only child. According to the national health commission in China, the number of families who lost their only child has risen to more than 1 million by 2011. and this number is estimated to be 10 million by 2035 [1] . This has become a social problem that cannot be ignored. Traditionally, children are considered to be not only a continuation of the bloodline but also emotional sustenance for parents in China. From generation after generation, Chinese parents tend to raise children in order to "carry on the family line" and "support parents when they are old". However, if parents lost their only child unfortunately, they would have to endure psychological suffering and cope with elderly care problems all by themselves [2] .
Losing only child will result in parents long-term poor mental health, affect their physical health and reduce the quality of their life and well-being. The visit time to hospital in lossof-only-child parents was significantly higher than that in parents who have a living child.
The mortality of coronary heart disease, tumor and mental diseases in loss-of-only-child parents (28.4%, 7.4%, 7.4%) were significantly higher than those in parents who have a living child (3.1%, 1.0%, 1.0%) [3] . Depression is one of such common mental diseases among the elderly parents who lost their only child. Therefore, people with psychological problems should be given timely attention and effective intervention. The World Health Organization (WHO) has predicted that depression will become the third leading cause of disability worldwide by 2020. Geriatric Depression Scale(GDS) was widely used to evaluate depression status. It is necessary to understand the depression status of the parents and it's influencing factors, to facilitate the exploration of effective, personalized interventions.
Heidi Sivertsen (2015) reviewed 74 original studies, and found that depression is associated with a lower quality of life and an increased risk of mortality [4] . Harry Owen 4 Taylor collected data of 1,439 older adults (55 years and above) from the National Survey of American Life, adopted CES-D to evaluate depressive symptoms, and discovered that subjective social isolation from friends only and from both family and friends was associated with more depressive symptoms [5] . Xiaofu Pan (2016) used a revised Posttraumatic Growth Inventory (PTGI-R) to assess posttraumatic growth (PTG), conducted the multiple linear regression analyses, and the study showed that a child's age at death, time since the death, and cause of death, parent's education and health, and community support are positively associated with the degree of posttraumatic growth [6] . Qianlan Yin (2018) interviewed 95 loss-of-only-child parents and 97 parents with a living child, adopted CES-D (Center for Epidemiological Studies Depression Scale) and GHQ-12 (General Health Questionnaire) to evaluate the parents' mental status, and found that loss-of-only-child family (Shidu) parents have more severe mental health problems than parents who have a living child [3]. Wen Zhang (2016) used the Posttraumatic Growth Inventory and the Connor-Davidson Resilience Scale to investigate 222 loss-of-only-child parents, used multinomial logistic regression to analyze the association between the demographic variables and resilience, and recommended that targeted intervention should be developed and timely attention must be paid to the mental health of the bereaved parents who are without a spouse and have low income [7] .
Lingyu Ran applied Symptom Check List-90 (SCL-90) and other scales to analyze the mental health status of Shidu parents and came to a conclusion that the mental health level of the Shidu parents was on the decrease significantly, and positive intervention has a positive effect on the mental health of the parents [8] .
Some preliminary evidence exists regarding the severity of depression of parents who lost their only child. However, there is a lack of quantitative studies. In addition, no studies 5 used GDS to measure depression status of the parents who lost their only child. Finally, some of the more important possible influencing factors were not included in the analysis, for example, the grandchildren, social support status, and quality of life. We hypothesized that there were some important social psychological factors associated with depression status of parents who lost their only child. We used GDS and adopted a generalized linear regression model to investigate the parents who lost their only child in Anshun city, Guizhou province, China, and aimed to comprehensively and systematically explore the depression status and it's influencing factors of the parents.

Sampling
Data were collected from March 1 st to April 30 th 2018 in Anshun city, Guizhou province, China, which was located in western China, and its economy is underdeveloped.
Participants were selected using the methods of stratified sampling and cluster sampling.
The sampling process involved a systematic approach and a three-step scheme: Firstly, according to geographical location, four districts of Anshun city were divided into two zones: east and west. Secondly, one district was selected from each zone: Xixiu and Kaifa, respectively. Thirdly, according to the method of cluster sampling, we selected some communities with the largest number of parents who lost their only child for the whole survey from each zone. The inclusion criteria were: The parents who lost their only child were equal to or older than 49, in view of the fact that the health bureau has the information of these parents aged at least 49 and mothers who lost their only child at this age would no longer be fertile. In addition, the participants must have normal cognitive functions, and be willing and able to cooperate throughout the investigation process. The exclusion criteria were: The parents who lost their only child had refused to accept the government's condolence and investigation. The parents moved to another place.
One teacher from Zhejiang Chinese Medical University and 15 family planning cadres in local communities were recruited and trained as interviewers. All respondents were clearly informed of the purposes of this study and asked to sign on the consent form. All respondents were assured of their rights to refuse to participate or to withdraw from this study at any time. Anonymity and confidentiality of the participants were assured. Each interview lasted for about 30 minutes. 130 participants were interviewed. There were 108 valid questionnaires, and the effective recovery rate was 83.1%.

Geriatric Depression Scale (GDS) was developed by the U.S. Brink and Yesavage in 1982,
which has 30 items in total. The simplified GDS-15 is a 15-item simplified scale designed by Sheikh and Yesavage in 1986 and is based on the standard version of 30 items according to the characteristics of the senior people [9]. It was used to evaluate their recent depression status, with particular focus on their feeling down, reduced activity, irritability, pain, withdrawal, and negative evaluation of the past, present and future. A higher score on the scale indicates more severe depression [9]. The GDS-15 has been widely used and its reliability and validity have been tested and supported [9]. The GDS-15 scores of the parents who lost their only child were regarded as the dependent variable in this study.

EQ-5D scale
European quality of life-5 dimensions (EQ-5D) scale mainly includes five dimensions: mobility, self-care, daily activities, pain or discomfort, anxiety or depression. Each dimension has three levels of "no difficulty", "some difficulty" and "total difficulty", which are used to evaluate the quality of life of the respondents. Due to the lack of calculation 7 method of China's EQ-5D index score at present, we chose to use the integral conversion table of Japan for calculation, and the scale index score is -0.11~1.00 points. A higher EQ-5D score indicates better health [10]. The EQ-5D scale has high internal consistency and reliability [10].

SSRS
Social Support Rating Scale (SSRS) has 10 items in total, which is divided into three dimensions: subjective support, objective support, and utilization of support. The sum of the scores of the three dimensions is the total score of the scale. A higher score indicates a higher level of social support. A total score of less than 20 indicates less social support, a total score of 20-30 indicates general social support, and a total score of more than 30 indicates satisfactory social support [11]. The SSRS has adequate internal consistency and reliability [11].
The number of chronic diseases was measured by the multiple-choice question, "How many chronic diseases do you have?" Sixteen chronic diseases were listed for selection, including diabetes, hypertension, hyperlipidemia, the malignant tumor, Cerebral infarction (stroke), cerebrovascular disease, coronary heart disease, senile dementia, chronic liver disease, gout, asthma, gynaecology disease, arthritis, tuberculosis (TB), hematopathy, chronic low back pain, osteoporosis, cataract. A higher score meant that participants had 8 more chronic diseases. However, self-rated health status was regarded as continuous variables in the generalized linear regression model.

Quality control
The respondents' ages were confirmed using the household registration system. During the face-to-face field survey, the trained teachers and family planning cadres in local communities explained how to fill in the questionnaires and helped respondents complete them in their homes or neighborhood committee office. The database was established by EpiData3.1, and double input was conducted to ensure accuracy.

Data analysis
Data were analyzed using the SAS version 9.1 software. Participant sociodemographic variables were expressed as frequencies. In view of the non-normal distribution of GDS score data, the rank sum test was used to compare the GDS score of the parents who lost their only child with different basic characteristics. The generalized linear univariate and multivariate regression models were conducted to analyze factors influencing GDS score.

Sociodemographic characteristics and basic situation of GDS score
The average age of these parents in this survey was 62.84 years old, the standard  Table 1. Their average GDS score was 5.64, the standard deviation was 3.71, the median and quartile were 4 and 5, the minimum and maximum values were 1 and 15 respectively. Table 1 presents the GDS score comparison of the parents who lost their only child with different basic characteristics. Rank sum test results were shown: The parents who lost their only child with different self-rated health status (P=0.004) and the number of chronic diseases (P=0.001) had different GDS scores. The parents who assessed themselves as in good health were less depressed than those who assessed themselves as in moderate and poor health. The parents who don't have chronic disease are less depressed than parents who do. The parents who suffer from one chronic disease are less depressed than the parents who suffer from two or more diseases. Table 2 presents the results of generalized linear univariate regression analysis of the factors associated with depression of parents who lost their only child. The deterioration of self-rated health status was significantly associated with the increase in depression risk (P=0.002). More number of chronic diseases was significantly associated with the increase in depression risk (P=0.002). The decrease in EQ-5D score was remarkably associated with the increase in depression risk (P<0.001), and depression risk increased as the SSRS score decreased (P<0.001). Table 3 presents the results of generalized linear multivariate regression analysis of the factors associated with depression of parents who lost their only child. EQ-5D score(P=0.019) and SSRS score(P<0.001) were significantly associated with the depression of the parents who lost their only child. The decrease in EQ-5D score was significantly associated with the increase in depression risk (P=0.019), and the increase in social support contributed to the reduction of depression risk (P<0.001).

Discussion 10
The purpose of this study was to clarify the depression status of the parents who lost their only child and its influencing factors in Anshun city, Guizhou province, China, and provide strategies to alleviate their depression. This study adopted a generalized linear regression model and found the following results: The parents who lost their only child of different self-rated health status (P=0.004) and the number of chronic diseases (P=0.001) had different GDS score. EQ-5D score(P=0.019) and SSRS score(P<0.001) were significantly associated with the depression of the parents who lost their only child.
Their average GDS score was 5.64, the standard deviation was 3.71. The standard cutoff score is 5 [12] .
Therefore, the average GDS score of these parents exceeds the standard cutoff score. This study is consistent with David J. Vinkers 's findings. He found that all respondents reported the bereavement to be a major negative life event. A negative life event was the most important risk factor for depression in the elderly [13]. Heidi Sivertsen also found that bereavement is a risk factor for depression [4]. Therefore, the parents who lost their only child are a high-risk group of people who may have depression, and targeted interventions should be carried out for them.
The results of this study showed that the parents who assessed themselves as in good health were less depressed than those who assessed themselves as in moderate and poor health. The parents who didn't have chronic disease were less depressed than parents who did. The parents who suffered from one chronic disease were less depressed than the parents who suffered from two or more diseases. Depression risk increased as the EQ-5D score decreased. None study on the aspect of the parents who lost their only child have been done before, while Heidi Sivertsen studied the ordinary elderly. The findings of this study is consistent with that of Heidi Sivertsen 's. He also found that physical morbidity and impaired level of functioning were associated with depression [4]. Alice Laudisio pointed out that depressive symptoms were associated with reduced Qol [14]. This may be because the physical illness affects mental health and therefore increases the risk of depression. Therefore, it is very important to maintain and manage the health of these parents. To help them, the family doctor contract service system is being vigorously promoted throughout China. These parents should be the key contracting service objects for family doctors. The family doctor team should increase the frequency and content of serving them, and promptly provide them with preventive and primary health care services. If they encounter diseases that cannot be solved, they need to be referred to a higher level hospital.
This study also discovered that the lower the SSRS score was, the more serious their depression was. The results of this study were similar to those of Harry Owen Taylor [5].
Everyone in society needs the care and help from others. These parents lacked an important source of social support after losing their only one child. Therefore, other social support resources provided by relatives, friends, social workers, government, society, etc.
will be very necessary and important because they help establish a diverse social support system. Heidi Sivertsen's study indicated that female gender and older age were associated with depression [4]. Derek Richards discovered that women were a high-risk group of depression [15]. However, we did not find it, possibly due to the particularity of the parents who lost their only child. Women are more likely to talk after being bereavement, which may reduce the probability of depression. Men are more likely to hide their sadness, which increases the probability of depression. Our study did not find that age is an influencing factor, probably because of the small sample size. This study has several strengths. First, a quantitative study on the depression status of the parents who lost their only child by using GDS was carried out. Second, for the first time, we conducted quantitative research in this area for the western cities where China's economy was underdeveloped. Third, the independent variables of the factors influencing depression were relatively comprehensive. Some limitations of the study should be acknowledged.
First, some of these parents who were studied had not yet entered the old age, but they were assessed by adopting the age-specific GDS. Second, only one city in western China was surveyed, and the sample size was small. Third, this study was a cross-sectional study and it is difficult to make a causal inference.This study systematically analyzed the depression status of these parents and its influencing factors, and provided a theoretical basis for relieving the depression of this special vulnerable group. China is working hard to improve people's livelihood. Relieving the depression of this group is one of the important issues that the government and the community need to pay attention to. This study can further arouse the attention and concern of all circles in this society. confidential and never leak. The committee has decided that a full review is not necessary, and decided to grant ethical approval waiver.
The written Informed consent was obtained from all individual participants included in the study.

Consent for publication
All authors have approved the final manuscript and consent for publication Availability of data and material The datasets generated and/or analyzed during the current study are not publicly available due to China's parents who lost their only child are a special vulnerable group, giving them some privacy protection, but are available from the corresponding author on reasonable request.

Competing interests
The authors declare that they have no conflict of interest. The funding sources had no role 14 in the design of this study and will not have any role during its execution, analyses, interpretation of the data, or decision to submit results.

Funding
The Tables Table 1The GDS   Note: a It includes divorced and widowed.