Frailty represents a global health issue with high prevalence and adverse health effects15,16. In our study, the probability of frailty in hypertensive patients was 11.9%. For patients with hypertension, accurate and prompt diagnosis of frailty is important because it allows for effective interventions and treatments17. Therefore, we established a reliable model to identify the risk of frailty in hypertensive patients and assist in its management to help clinicians and patients share decisions.
In our research, we utilized LASSO regression to screen variables and adjust for complexity. Compared to the univariate regression analysis, Lasso regression can minimize the multicollinearity in variables. The nomogram contains four risk factors, including age, health status, cognitive function, and CES-D. The use of the nomogram is that the corresponding predicted values are first transformed into the corresponding nomogram scores. The scores are summed, and the probability of a hypertensive patient being frail is derived from the realistic values at the intersection points. The AUCs and calibration curves suggested that the nomogram had good discrimination and accuracy in both the training and validation cohorts, while the DCA curves further showed that the nomogram conferred high clinical net benefits.
At present, most of the studies on frailty have been done on the Western population; few have been done on the Chinese or oriental populations. Recently, standardized definitions of frailty have been proposed, which were characterized by unintentional weight loss, self-reported fatigue, weakness, slower walking speed, and reduced physical activity8,18. Due to the aging and increasingly complex nature of cardiovascular patients, there is growing awareness of frailty in cardiovascular medicine14,19. The selection of hypertension treatment might also be influenced by frailty. Frail older adults are always excluded from randomized controlled trials (RCTs) for cardiovascular disease, including hypertension20. This limited the generalizability of the results, making it difficult to accurately evaluate the safety and effectiveness of chronic disease treatments for frail individuals. Secondly, frailty is associated with reduced life expectance and lifetime morbidity. According to the results of the SHARE study, the life expectance of males was 0.1–0.8 years, and females was 0.4–5.5 years in frail individuals at age 7021. Thus, the duration of benefit from specific treatments may exceed life expectancy in frail individuals22. Finally, frailty is linked to poor adherence to antihypertensive medication23.
Aging is the primary risk factor for the majority of chronic diseases24. Over increasing timescales, all people accumulate molecular and cellular damage, and these aging processes, including inflammation, genomic instability, and epigenetic changes, are highly inter-correlated25,26. Many of these processes are related to frailty. The prevalence of frailty among community-dwelling elderly increases with advanced age: 4% for elderly aged 65 to 69 years, 7% for elderly aged 70 to 74 years, 9% for elderly aged 75 to 79 years, 16% for elderly aged 80 to 84 years, and 26% for elderly aged 85 and over. Besides, we found that frailty has a tight correlation with cognition. Previously, it was demonstrated that changes in physical activity and disease are highly correlated with cognitive and functional outcomes in the elderly27–29. Cognitive function and frailty may be related by pathogenic mechanisms such as chronic inflammation and oxidative stress30. Reduced cognitive function can decrease the self-care ability and adherence to hypertension treatment, which further exacerbates disease progression and leads to a higher risk of frailty. Depressive symptoms were assessed using the CESD score. Depression predicts frailty due to reduced social relationships, gait speed, and physical activity31. Subclinical vascular disease (white matter disease) in patients with late life depression has been considered a key factor in pre-frailty32,33. Accumulating evidence supports a positive association between frailty and inflammatory cytokines such as IL-6, which is also elevated in depressed patients34,35. Mitochondrial dysfunction has been observed in several neurodegenerative diseases. Muscle biopsies obtained from depressed participants had decreased ATP production and impaired mitochondrial respiration, which is strongly associated with symptoms of frailty36. Furthermore, depression can adversely affect psychological status and exacerbate debilitating episodes by reducing social activities. Health status plays a direct role in frailty. The comorbidities of cardiovascular disease can exacerbate the clinical course, compromise treatment, and worsen outcomes37,38. The burden of cardiovascular disease is associated with increased short and long-term morbidity39,40.
However, our study still has some limitations. First, the CHARLS data did not include a number of potential predictors in hypertension, such as metabolic syndrome and family history. Moreover, the nomogram was constructed based on the Chinese population, and its applicability to populations in other countries requires further validation by an external validation cohort. Lastly, originating from a retrospective cohort, the nomogram needs to be verified using a larger sample size and prospective set.