In this multicenter, nationwide, prospective Chinese AMI patient registry, the major findings of present analysis are as follows: 1) Compared with not living alone group, young and middle-aged patients with AMI in living alone group had not significant difference in the crude rate of in-hospital mortality. 2) Patients who lived alone were associated with an increased risk of 2-year all-cause mortality and MACCEs compared to those who lived together. This association remained significant even after adjusting for potential confounding variables. 3) Living alone significantly increased the risk of 2-year all-cause mortality in men, GRACE score > 140, and hypertension subgroups.
This is the first study aimed at evaluating the relationship between living status and short-term and long-term outcomes in young and middle-aged patients with AMI. From the baseline characteristics of our cohort, living alone patients was generally paid by themselves during hospitalization, and higher rate of cardiac arrest on admission than not living group. The risk of cardiac arrest upon admission for young and middle-aged patients with AMI who lived alone was increased partly due to delayed medical attention caused by a lack of timely reminders from others and the failure to promptly administer cardiopulmonary resuscitation and other emergency medical interventions. In contrast with many stereotypes, before the occurrence of AMI, living alone patients were more likely to have a lower prevalence of cardiovascular comorbidities, such as diabetes, hypertension, and hyperlipidemia. Firstly, they typically had better control over their living environment and dietary habits. Additionally, patients living alone often took on the responsibility of managing and controlling chronic conditions themselves. They tend to be more conscientious in adhering to medical advice, promptly adjusting treatment plans, and effectively controlling cardiovascular risk factors.
In our present study, there was no remarkable difference in in-hospital mortality rate between patients living alone and those not living alone. Part of the explanation could be ascribed to the fact that young and middle-aged patients with AMI typically did not exhibit obvious comorbidities or significant risk factors for cardiovascular disease. During hospitalization, patients of both living alone and non-living alone received comprehensive and standardized medical monitoring and care. Medical practitioners promptly intervened and managed patients based on their individual conditions, ensuring the provision of appropriate care regardless of their living status. Furthermore, it is worth noting that our study had a limited sample size for in-hospital outcomes, which might underestimate the impact of living status on in-hospital mortality. Although the living status did not reveal a noticeable disparity in in-hospital mortality between living alone and not living alone groups, our present study elucidated a distinct and consistent protective effect of not living alone during long-term follow-up after AMI. Following discharge, patients who did not live alone was associated with a lower 2-year all-cause mortality and MACCEs in comparison to those who lived alone. This association remained significant even after adjustment for potential confounding variables. Several factors have been proposed to explain the association between living alone and adverse long-term outcomes in young and middle-aged patients with AMI. Studies reported associations between living alone and changes in sympathetic activity and increased catecholamines, which activated platelets and macrophages, led to higher levels of interleukin-6 (IL-6), and eventually contributed to development of atherosclerosis and poorer cardiovascular outcomes (17). After discharge, patients who lived alone were at greater risk of psychological stress and depression, which may aggravate the adverse cardiovascular outcomes caused by these factors via limiting social support and human contact (18). With the changes in marriage concepts and the high cost of living in modern society, the number of young and middle-aged people living alone has been continuously increasing worldwide. However, due to lacking for care and emotional support of others, people living alone would tend to have less medical supervision and encouragement to maintain a healthy lifestyle, this may be more important in younger patients (19, 20). Furthermore, younger adults who live alone have greater exposure to unhealthy behaviors, such as smoking, poor diet, and physical inactivity, which might also account for the negative effect (21, 22).
The present results were consistent with several previous studies indicating a significant relationship between living alone and prognostic outcomes after AMI. In the Multicenter Diltiazem Postinfarction Trial, living alone was an independent risk factor for recurrent cardiac events after AMI (HR = 1.54 [95% CI: 1.04–2.29], P < 0.03) (13). Similarly, after adjusting for potential confounding factors, Nielsen et al. (23) found that living alone was an independent predictor of death among employed patients with AMI, with a HR of 2.55 (95% CI: 1.52–4.30). In a study aimed specifically at older women, Norekval et al. (24) demonstrated a higher rate of 10-year mortality after AMI in older women living alone. Furthermore, Schmaltz et al. (6) also found that living alone was independently associated with 3-year mortality with AMI (HR = 1.6 [95% CI: 1.0-2.5]). Compared with woman living alone (HR = 1.2 [95% CI: 0.7–2.2]), man who lived alone had a higher risk of mortality post-discharge (HR = 2.0 [95% CI: 1.1–3.7]).
In our present study, with stratification of living status by patient sex, diabetes, GRACE score stratification, hypertension, and smoking, living alone also significantly increased the risk of 2-year all-cause mortality in men but not in women, indicating that the observed association between living alone and post-AMI prognostic implications also varied by patient sex. Previous study demonstrated that depression could potentially serve as the exclusive mediator linking living alone status to mortality post-AMI. Moreover, there existed a gender disparity between living alone and post-AMI depression. Specifically, men who lived in solitary conditions exhibited a higher propensity for depression (25), which was linked to detrimental cardiovascular outcomes. Besides, living alone might potentially contribute to suboptimal compliance with medication and treatment, as well as inadequate adherence to follow-up recommendations. The impact of this correlation might differ based on the patient's gender. Unfortunately, our study lacked pertinent data to investigate the potential role of these factor as a confounding or effect-modifying factor. There was also a significant increase in 2-year all-cause mortality rate among patients living alone with respect to GRACE score > 140 and hypertension. These were likely attributable to the factor that patients living alone generally need self-management of diseases, lack of supervision and reminders from family and friends, and can impede effective control of cardiovascular risk factors such as hypertension and diabetes, which may lead to disease progression and increase the risk of complications. Although our present study did not find a significant increase in 2-year all-cause mortality rate in patients living alone with diabetes, the adjusted HR was very close to 1, suggesting that expanding the sample size may obtain meaningful results.
Although these studies demonstrated the association between living alone and prognosis after AMI, several other previous reports did not show independent relationship between living alone and outcomes. For example, date from the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) III trial, AMI patients living alone had a higher crude 1-year mortality compared with patients living with others, but there was no significant difference in 1-year mortality rates after adjustment for confounding factors (26). Emily et al. (18) also found that living alone was not associated with mortality, readmission, or other health status measurements after adjusting for patient and clinical characteristics. Similarly, Berkman et al. (12) found that there was no significant difference in survival in elderly patients living alone versus those living with others after AMI. These different findings may be partially explained by differences in methodology, study sample characteristics, and length of follow-up. For example, the New Haven longitudinal community-based cohort study exclusively enrolled patients with AMI aged 65 years and older, potentially limiting the broader applicability to diverse patients (12). Additionally, many clinical studies predominantly focused on Western populations, inevitably limiting the generalizability of research outcomes to heterogeneous populations.
Currently, studies for AMI mainly focus on the whole or elderly population. With the increased number of young and middle-aged people living alone, great attention should be paid to the impact of the living status on the prognosis with AMI. The present study showed that living with others had a healthy premium on the prognosis of young and middle-aged patients with AMI. Through preventive interventions for young and middle-aged patients living alone, the adverse prognosis gap between living alone and not living alone patients could be reduced.
Nevertheless, there are several limitations in our study. Firstly, the missing or incomplete information and the potential unincluded confounding factors should be considered in the interpretation of results. Secondly, living status is dependent on the description provided by patients or their relatives, which might exist reporting bias. Thirdly, the living alone group in our study is limited in sample size which might influence the validation of our hypothesis. Relevant studies with larger samples are needed in the future.
In conclusion, the results from our study supported that living alone was independently associated with a substantially increased risk of adverse events during the first 24 months after AMI in young and middle-aged Chinese individuals but did not show an extra in-hospital mortality rate after covariate adjustment. Consideration of living arrangements and household support for living alone young and middle-aged patients with AMI may prevent the poor outcomes.