Loneliness associated with higher CVD risk in DM
Joint association of loneliness and traditional risk factor control and incident cardiovascular disease in diabetes patients
Loneliness and social isolation are both related to a higher risk of CVD [1-3]. Although patients with DM experience higher levels of loneliness and social isolation than individuals with no DM [4,5], little is known about the association of these factors with CVD risk in this patient population. It is also unclear whether the association between traditional risk factor control and CVD risk differs by the status of loneliness or social isolation.
Aim of the study
The authors investigated the prospective associations of loneliness and social isolation scores with CVD risk in DM patients and compared the relative importance of loneliness and social isolation in predicting CVD risk with that of traditional risk factors. Additionally, they evaluated the interactions of loneliness and isolation with the degree of traditional risk factor control in relation to CVD risk.
In this observational, population-based cohort study, data of 18,509 participants diagnosed with DM were extracted from the UK Biobank. Exclusion criteria were prevalent CHD, stroke, or HF. To assess loneliness, a 2-item scale was used, and a 3-item scale was used to measure levels of social isolation. The degree of traditional risk factor control was defined as the levels of HbA1c, blood pressure (BP), LDL-c, smoking status, and control of kidney condition. Mean follow-up time was 10.7 years.
The primary endpoints were total incident CVD events and its 2 major components (CHD events and stroke).
Association of loneliness or isolation scores with CVD risk
- During follow-up, 3472 CVD incidents were observed, including 2771 CHD events and 701 strokes.
- In the fully adjusted model (i.e., multivariable model further adjusted for lifestyle factors, depression score, and traditional risk factor control), patients with a loneliness score of 1 had a higher risk of CVD compared with patients with a loneliness score of 0 (HR: 1.11; 95%: 1.02–1.20; P for trend<0.001). For patients with a loneliness score of 2, the CVD risk was also increased compared with the group with the lowest loneliness score (HR: 1.26; 95%CI: 1.11–1.42; P for trend<0.001).
- The CHD risk was also increased in patients with a loneliness score of 1 (HR: 1.13; 95%CI: 1.04–1.23; P for trend<0.001) and a score of 2 (HR: 1.26; 95%CI: 1.10–1.44; P for trend<0.001) compared with 0-score group. However, the loneliness score was not significantly associated with stroke.
- There were also no significant associations between the social isolation score and CVD, CHD, or stroke.
Relative importance of loneliness and isolation compared with other risk factors in predicting CVD risk
- Loneliness was in fifth place for predicting CVD risk. It ranked lower in relative strength than LDL-c, BMI, and albumin-to-creatinine ratio; similar to eGFR, HbA1c, and systolic BP; and higher than depression score, the Townsend deprivation index, and lifestyle risk factors such as smoking, physical activity, and diet.
- Of the selected 13 factors, social isolation came in last place.
Joint association of loneliness and degree of risk factor control with CVD risk
- Compared with individuals who had a high degree of traditional risk factor control (4–5 risk factors controlled) and did not feel lonely, individuals with a low degree of risk factor control (0–1 factor) who did not feel lonely showed an increased CVD risk (HR: 1.50; 95%CI: 1.30–1.73).
- Among participants who felt lonely, the HR further increased to 1.93 (95%CI: 1.47–2.54) for those with a low degree of risk factor control compared with those with a high degree of control.
- There was an additive interaction between loneliness and the degree of risk factor control on CVD risk (P for additive interaction=0.005). The relative excess risk due to interaction was 0.11 (95%CI: 0.03–0.18). The attributable proportion to the additive interaction was 8.5% (95%CI: 4.2%–12.8%), meaning that if both loneliness and a low degree of risk factor control were present, this would result in an additional 8.5% of CVD cases.
This observational, population-based cohort study using UK Biobank data showed that loneliness, but not social isolation, was associated with a higher CVD risk in patients with DM. Loneliness ranked higher in relative strength for predicting CVD risk than lifestyle risk factors such as smoking, physical activity, and diet. In addition, the CVD risk associated with a combination of loneliness and a low degree of traditional risk factor control was greater than the addition of the risks associated with each of these factors. The authors conclude that their “results highlight the importance of loneliness in the prediction of CVDs among diabetic patients.”