Among diabetes patients, loneliness, but not social isolation scale, is associated with a higher risk of CVD

byJoaquim Cardoso

28 de julho de 2023

7 minute read

the health strategist
review

management, engineering and
technology review

Joaquim Cardoso MSc.

Chief Research Officer (CSO), Chief Editor
Chief Strategy Officer (CSO) and Senior Advisor

July 28, 2023

What is the message?

Key takeaways:

Aims

To investigate the prospective associations of the loneliness and social isolation scales with cardiovascular disease (CVD) risk in diabetes patients and compare the relative importance of loneliness and social isolation with traditional risk factors.

Also, the interactions of loneliness or isolation with the degree of risk factor control in relation to CVD risk were evaluated.

Methods and results

A total of 18 509 participants diagnosed with diabetes from the UK Biobank were included.

A two-item scale and a three-item scale were used to assess loneliness and isolation levels, respectively.

The degree of risk factor control was defined as numbers of glycated hemoglobin (HbA1c), blood pressure (BP), low-density lipoprotein cholesterol (LDL-C), smoking, and kidney condition controlled within the target range.

During a mean follow-up of 10.7 years, 3247 total CVD incidents were documented, including 2771 coronary heart disease and 701 strokes.

In the fully adjusted model, compared with participants with the lowest loneliness score (zero), hazard ratios (95% confidence interval) for CVD were 1.11 (1.02 and 1.20) and 1.26 (1.11 and 1.42) for participants with a loneliness scale of 1 and 2, respectively (P-trend < 0.001).

No significant associations were observed for social isolation. Loneliness ranked higher in relative strength for predicting CVD than the lifestyle risk factors in diabetes patients.

A significant additive interaction between loneliness and the degree of risk factor control on the risk of CVD was observed (P for additive interaction = 0.005).

Conclusion

Among diabetes patients, loneliness, but not social isolation scale, is associated with a higher risk of CVD and shows an additive interaction with the degree of risk factor control.

Structured Graphical Abstract

DEEP DIVE

Joint association of loneliness and traditional risk factor control and incident cardiovascular disease in diabetes patients [excerpt]

European Heart Journal
Xuan Wang, Hao Ma, Xiang Li, Yoriko Heianza, Vivian Fonseca, Lu Qi
29 June 2023

Introduction

Individuals with diabetes have a two- to three-fold higher risk of cardiovascular disease (CVD) than individuals without diabetes.1,2 Recently, the American Heart Association issued a statement calling for attention to the importance of the social determinants of health (SDOH) in diabetes patients in addition to traditional risk factors.3 However, the relevant evidence is still lacking.

Loneliness and social isolation are two important components of SDOH, reflecting different aspects of social contact.4,5 Loneliness usually refers to the emotional feelings related to the quality of social relations, while isolation refers to the quantity of social relations in behavior.6,7 Although the concepts of loneliness and social isolation are often discussed and compared to each other, they are quite different in nature and have different health consequences.6–9 Several previous studies in the general population have found that loneliness and social isolation are both significantly related to a higher risk of CVD.6,10,11 Notably, growing evidence shows that individuals with diabetes experience significantly higher levels of loneliness and isolation than individuals without diabetes,12,13 whereas little is known about the association of loneliness or social isolation with CVD risk in diabetes patients.

Moreover, previous studies showed that controlling for multiple traditional risk factors, such as high glycemia, high blood pressure (BP), dyslipidemia, smoking, and a poor kidney condition, might lower but not entirely eliminate the diabetes-related excess risk of CVD.14,15 It is unclear whether the association between traditional risk factor control and the risk of CVD differs by the status of loneliness or isolation. Therefore, in this study, we investigated the prospective associations of the loneliness and social isolation scales with CVD risk in diabetes patients and particularly compared the relative importance of loneliness and social isolation to traditional risk factors (e.g. lifestyle factors and metabolic risk factors) in predicting CVD risk. Moreover, we also evaluated the interactions of loneliness or isolation with the degree of risk factor control in relation to CVD risk by applying multiplicative interaction and additive interaction more relevant to the public health measures.

Methods

See the original publication (this is an excerpt version)

Discussion

This study generated two key findings. First, we found that a higher loneliness scale, but not social isolation scale, was significantly associated with a higher risk of CVD in diabetes patients, and loneliness ranked higher in relative strength for predicting CVD than the lifestyle risk factors (Structured Graphical Abstract). Second, we observed that the risk of CVD associated with a combination of loneliness and a low degree of traditional risk factor control was greater than the addition of the risk associated with each of these factors, indicating a significant interaction on an additive scale.

Our study, for the first time, showed that loneliness was significantly related to a higher risk of CVD in diabetic patients. Our findings were supported by the results from several previous studies studying the general population, in which loneliness was found to be associated with higher risks of CVD events.32,33 A cohort study from England showed that a one-point increase in the loneliness scale was associated with a 5%–8% increase in the hazard of CVD in the general population.32 Another study from the UK showed that loneliness was significantly associated with a higher risk of acute myocardial infarction in the general population when separately adjusting for biological factors, health behaviors, depressive symptoms, or socioeconomic factors, whereas such an association was no longer significant when these factors were fully adjusted in the model (HR 1.06, 95% CI, 0.96–1.17).11 In our study, the associations between the loneliness scale and the risks of CVD and CHD among diabetes patients remained significant after adjusting for similar covariates. Our findings could be potentially explained by the evidence that diabetic patients not only have a higher risk of CVD but also experience higher levels of loneliness than individuals without diabetes.13 Moreover, we compared the relative importance of loneliness with traditional risk factors in predicting CVD among diabetes patients and found that the relative strength of loneliness was greater than the lifestyle risk factors, including smoking, physical activity, and diet.

In this study, we did not find a significant association between social isolation and CVDs among diabetes patients. Consistent with our findings, a prospective study from the Women’s Health Initiative also did not find a significant association between social network size (constructed by married or in an intimate relationship, times attending activities, and number of relatives) and CHD risk among women with diabetes.34 Our findings are also supported by the results of intervention studies examining the impact of social support on outcomes in diabetes patients,35–40 which found that behavior-related interventions had no effect on changes in cardiometabolic biomarkers such as HbA1c and BP,36,37 whereas emotion-related interventions such as peer support consistently resulted in greater improvement in these biomarkers.38–40 Different from loneliness, which refers to a negative emotional feeling toward social contacts and relationships, social isolation refers to the scarcity of social contacts and relationships in behavior.6,41,42 Our findings suggest that the quality of social context (emotional) may play a more important role than quantity (behavioral) in determining CVD among diabetes patients.

We observed that among diabetes patients, the CVD risk associated with a combination of loneliness and a low degree of risk factor control was greater than the addition of the risks associated with each of these factors, indicating a significant interaction on an additive scale. Specifically, if both loneliness and a low degree of risk factor control were present, this would result in an additional 8.5% of cases of CVD. The observed effect size of additive interaction in this study is modest in magnitude. However, given the high prevalence of diabetes and the increasing trend worldwide, such a percentage increase is considerable regarding the number of patients affected by CVD complications and therefore has important public health implications. The additive interactions could distinguish whether the effect of the risk factor on a certain disease differed across subgroups; thus, they are more relevant to public health as compared with multiplicative interactions. Our findings indicate that the public health consequence of a low degree of risk factor control would be greater in diabetes patients with loneliness.

The major strengths of this study include the prospective study design, the large sample size of diabetes patients with available data on loneliness and isolation, and the comprehensive and detailed information on covariates in diabetes patients. We also acknowledge several potential limitations of this study. Firstly, due to the nature of an observational study, we cannot draw any conclusions about the causality between the loneliness scale and the risk of CVD. Second, the loneliness and social isolation scales were constructed based on simple questions, which may not be able to adequately assess the complex phenomenon of social networking and interaction. However, these scales have been widely used in several previous studies from different cohorts,7–9,11,43 suggesting such scales are effective in population studies. Third, despite the large sample size of the study and long follow-up period, the incidence of stroke was still low; thus, our results on stroke should be interpreted as exploratory. Fourth, we did not adjust for cognitive function in this study because only a limited number of UK Biobank participants completed the cognitive test at baseline. Future studies considering these factors are warranted. Fifth, only ∼12% of our study participants were non-White European; whether our findings could be generalized to other race/ethnic groups would need to be further tested. Sixth, the participants from the UK Biobank are more likely to have healthier behaviors and may not be a representation of the general UK population.16 However, a valid assessment of exposure–disease relationships may not require a representative population.44

Conclusion

Our findings indicate that a higher loneliness scale, but not isolation scale, was significantly associated with a higher risk of CVD in diabetic patients, and loneliness ranked higher in relative strength for predicting CVD than the lifestyle risk factors. The effect of loneliness and a low degree of risk factor control on the risk of CVD is greater than additive among diabetic patients. These results highlight the importance of loneliness in the prediction of CVDs among diabetic patients.