Physical multimorbidity and lifetime suicidal ideation and plans among rural older adults: the mediating role of psychological distress

Suicide is a serious public health issue worldwide and nearly 800,000 people died from suicide every year. Although the overall suicide rate in China has decreased over the past few decades [1, 2], it remains high among the elderly in China [3]. A recent study indicated that suicide rate among the elderly aged 65–85 years was 2.75–7.08 times higher than that of the general population in China [4]. According to World Health Organization (WHO) report, the suicide rate was highest in population aged over 70 years across different regions in the world. Currently, the suicide rate is about 51.5 per 100,000 people among the elderly in China [5, 6]. This rate was found to be significantly higher among older people in rural than that in urban areas [7, 8]. A study revealed that the mean annual suicide rate among the elderly aged 60–84 years in rural and urban areas was 82.8 per 100,000 people and 16.7 per 100,000 people, respectively [9]. With a rapid increase of elderly population, there is an urgent need to prevent suicide among the older adults, especially in rural areas.

Previous studies have shown that suicidal ideation, plans, and attempts were important predicators of later suicide [10–13]. The early detection of suicidal ideation and plans is one of the critical primary prevention measures for suicide [14]. However, the current prevention measures mainly focus on the secondary prevention (suicide attempts) and the tertiary prevention (suicide) [15, 16]. Therefore, to identify potential influencing factors for suicidal ideation and plans is of priority.

Physical chronic conditions were found to be related with higher odds of reporting suicidal behaviors among the elderly [17, 18]. Moreover, more and more people were found to be affected by more than one physical condition, especially among the elderly [19, 20]. The existence of two or more physical chronic conditions in an individual was known as multimorbidity [19]. Previous studies in some other countries further found that multimorbidity was associated with suicidal related behaviors. A study by Scott and colleagues revealed that the risk of suicidal outcomes was increased with the increase of the number of physical chronic conditions [21]. Another study in Korea showed that the adults with multimorbidity experienced higher prevalence of suicide thoughts and plans [22]. Although previous studies have demonstrated that the relationship between multimorbidity and suicidal ideation/plans, few studies have explored this association among the elderly, and the underlying potential mechanism or pathways on this relationship is still rarely explored.

Psychological distress (PD) is largely defined as a state of emotional suffering, typically characterized by depressive and anxiety symptoms. PD is an important and widely-used indicator in evaluating the psychological health of the population [23–25], which was assessed by Kessler Psychological Distress Scale (K10) in the present study. The relationship between single chronic conditions (such as cancer, diabetes, hypertension) and mental disorder has been well established [26]. Recently, more and more studies have focused on the relationship between multimorbidity and PD. A study conducted in Australia showed that the risk of PD increased with the number of chronic conditions in adults [27]. Another study further showed that three or more chronic conditions conferred a 2.30-fold increase in elevated anxiety among the older adults [28]. Furthermore, a number of studies have examined the association between PD and suicidal related behaviors and revealed that PD was correlated with suicidal ideation, plans and attempts [29, 30]. Similarly, PD was also found to be the strongest predicator of suicidal ideation across different age groups [31]. About 90% of suicides were found to have mental disorders before their death [32]. Thus, PD might be a mediator between the association between chronic conditions and suicidal ideations or plans.

The aim of the present study is to investigate the prevalence of suicidal ideations/plans and further examine the association between physical multimorbidity and suicidal ideation and suicidal plans, as well as to explore the mediating role of PD on this relationship among rural elderly in China. The main hypotheses of this study are as follows: First, there is a significant association between physical multimorbidity and suicidal ideations as well as suicidal plans in rural older adults; Second, PD is a mediator between multimorbidity and suicidal ideations as well as suicidal plans in rural older adults.

This population-based study found that physical multimorbidity was associated with lifetime suicidal ideation as well as suicidal plans in rural older adults. For the first time, this study tried to explore the potential mediating effect of PD on this relationship, and the results showed that PD was associated with suicidal ideation as well as suicidal plans, and partially mediated the association between multimorbidity and suicidal ideation/plans.

The present study found the prevalence of lifetime suicidal ideation and suicidal plans in rural elderly (60+) was 10.6 and 2.2%, respectively. The prevalence of suicidal ideation in present study was much higher than the 4.8% among rural elderly (65+) in Beijing reported by Ma et al. [40], the 5.2% in rural older adults (65+) in Shandong reported by Ge et al. [41], and the 9.4% among U.S. Chinese elderly (60+) reported by Dong and colleagues [42]. Meanwhile, the prevalence of suicidal plans in this study was higher than the 0.51% among elderly (65+) in Spain reported by Miret and colleagues. The lifetime prevalence of suicidal ideation and suicide plans in present study were both lower than 34.5 and 10.3% of elderly (65+) in a remote rural area of China that found by Chiu et al. [11]. One possible reason for such difference is that the sample size of Chiu et al.’ s study was relatively small and only 87 participants were included in the study. Another possible reason is that, the prevalence of suicidal ideation/plans was age-related. The older the elderly, the higher the prevalence. The age inclusion criteria by Chiu et al.’ s study was 65 years and above, which was older than the current study.

Congruent with our hypothesis, we found that the presence of two or more physical chronic conditions were significantly associated with suicidal ideation and suicidal plans. In the fully adjusted model, the elderly with two or more chronic conditions had higher odds of experiencing suicidal ideation and plans compared to those without any physical condition. This finding was consistent with a previous study, which demonstrated that the increasing number of chronic conditions were related with higher risks of suicidal ideation and plans in US population [43]. Huh et al. reported elderly (65+) with multimorbidity had higher prevalence of suicidal thoughts than those without multimorbidity in Korea [22]. Some previous studies showed that compared with those with no physical conditions, the elderly with multimorbidity were more likely to have disability, poor physical and mental health-related quality of life [44, 45], and it is intolerable for some older adults when these adverse consequences have accumulated to a certain extent. That was to say, multimorbidity may cause more seriously adverse health outcomes, thus increased the likelihood of suicidal ideation/plans of the patients.

Furthermore, we found that PD were independently associated with both multimorbidity and suicidal ideation/plans, and partially mediated the association between them. Although there was no study to explore the mediating role of PD in the association between multimorbidity and suicidal ideation/plans, a previous study conducted in China suggested that depression partly mediated the association between multimorbidity and health-related quality of life in older adults [46]. As mentioned above, the possible interpretation of this finding might be that the multiple adverse outcomes caused by multimorbidity may directly or indirectly increase the risk of PD, which in turn further stimulates the occurrence of the suicidal ideation/plans. A review suggested that the patients with multimorbidity were twice as likely to experience depression than those without multimorbidity [47]. A study conducted in Canada indicated that people with obesity and multimorbidity had higher probability of reporting mental disorders [48]. In addition, multimorbidity was associated with increased risk of loneliness, social exclusion, function limitations, and economic burden, all of which may negatively affect the PD [49–51]. Several previous studies also found that PD was one of the strongest influencing factors of suicidal related behaviors [52, 53]. Thus, multimorbidity may have indirect effect on suicidal ideation as well as suicidal plans via inducing the PD. Some previous studies demonstrated that health care utilization and spending increased with the number of chronic conditions among the elderly [54–56], and a large proportion of the healthcare cost for multimorbidity was out-of-pocket paid by the rural elderly themselves, which may be more economically disadvantaged and impose financial hardship for their households. Moreover, as the origin of the Confucius culture, the elderly in rural Shandong were more traditional and conservative [57]. For those with multiple chronic conditions, they were fear of becoming a burden to their families and bearing higher level of PD for a long time. This existence of mental disorders may be one of the triggers of stressful life events, and ultimately increase the risk of suicide [58].

The findings in this study implied for the healthcare providers in rural communities to strengthen the regular screening and management of chronic conditions among the elderly to prevent or retard the presence of the multimorbidity, and further to reduce the chronic condition burden. More importantly, a regular surveillance for the mental health status should be taken among the rural elderly with multimorbidity, and various effective intervention measures should be carried out to improve the mental health status, so as to reduce the risk of suicide.

This study had several limitations. First, the information about number of physical chronic conditions and suicidal ideation/plans was self-reported, which might lead to recall basis. Second, although the US National Comorbidity Survey (NCS) and many previous studies have used the question “Have you ever seriously considered about suicide/killing yourselves?” to measure suicidal ideation, this question cannot be used as a standard instrument for assessing suicidal ideation. In addition, although previous studies have found that older adults who committed suicide were more likely to have antidepressants detected in the blood [59], the information about diagnosed mental illness and medication (e.g., antidepressant use information) was not collected in our study, which would be remedied in the follow-up studies. Third, based on the availability of data, we only examined the relationship between the number of chronic conditions and suicidal ideation/plans, further studies would investigate whether the pattern, length, or severity of chronic conditions were associated with suicidal ideation/plans. Fourth, the present study was based on cross-sectional design, so we could not infer the casual relationship between multimorbidity, PD, and suicidal ideation as well as plans, prospective studies were needed in the future to elucidate the causal association.

This study demonstrated the significant associations between physical multimorbidity and suicidal ideation/plans, and the mediating role of PD on this relationship among Chinese rural elderly. In rural areas, policy makers and healthcare providers should strengthen the prevention and management of chronic conditions among the elderly, to prevent or retard the presence of chronic conditions, especially the multimorbidity. In addition, a regular surveillance for the mental health status should be taken among the rural elderly with multimorbidity, and various effective intervention measures should be carried out to improve the mental health status, so as to reduce the risk of suicide.