The most frequent perioperative problems in postoperative major surgical patients are postoperative neurocognitive disorders (PNDs), which comprise postoperative delirium (POD), a short-term neurological issue, and postoperative cognitive impairment (POCD), a long-term effect.1 PND is characterized by fluctuating changes in arousal, a sudden and rapid onset, difficulty focusing and cognition as a result of an acute medical condition, which may cause falls, a rise in re-admissions to the hospital, institutionalization, and elderly people dying prematurely.2 PND is prevalent in patients undergoing various surgeries, 3, 4, 5, 6, 7 particularly in cardiac and orthopedic surgery, accounting for 6 %–46 % and 5 %–14 %, restrictively.3,6 Age is a high-risk factor for PND on its own, particularly in individuals over 65 years old. Likewise, frailty is a condition that typically preexists in the elderly and affects the neuromuscular system, metabolism, and immune system. This condition raises the risk of death, disability, falls, and long-term hospital adverse events.8,9 Age-related frailty in postsurgical patients is a widespread problem in society. The prevalence of frailty among elderly people over 65 years old is 7 %, the proportion of frail elderly people over 80 years is higher than 20 %, and elderly people over 90 years old is as high as 30 to 40 %.10 Previous data also suggested that frailty has a significant correlation with POD or POCD.11,12 One meta-analysis also demonstrated that frailty in prospective cohort studies shows a more significant correlation between frailty and PND compared with a retrospective study in patients undergoing surgery.13 In the presence of advanced diagnostic techniques and multidisciplinary cooperation, clinicians pay more attention to the relationship between the preoperative condition of the patient and postoperative complications.14 In addition, due to the increasing aging population in the whole world, publications on frailty and PND have increased significantly.14 One study investigated the use of point-care ultrasound to detect frailty and predict postoperative outcomes, found preoperative ultrasound measurements of quadriceps depth showed promise in discriminating between frail and not-frail patients before surgery, and it was also associated with skilled nursing facility admission and postoperative delirium.15 The frailty scale, initially introduced by the Fried team in 2001, proposed that weakness was a combination of five phenotypes: weight loss, reduced handgrip strength, slower pace, reduced physical activity, and conscious fatigue.10 In 2002 and 2005, Mitnitski et al.16 and Rockwood et al.17 proposed that they consider frailty not only a simple combination of the above five phenotypes, but a comprehensive assessment of 92 items in four aspects: symptoms, signs, dysfunction, and laboratory examination. As the study of frailty is increasing, various different assessment methods have emerged according to the attention variables, and the results are also different by using different evaluation methods. The new consensus published in 2012 argued that the frailty index not only includes physical health but also emphasizes the status of mental health and cognitive function in the frailty index.18

In recent years, bibliometric has been applied to assess the linkages and impacts of published articles and citations.19 Although the bibliometric method can clarify the research trends in one area, most studies only analysed the trends based on the software and did not make an elaborate analysis. Therefore, to illustrate and visualize the correlation between frailty and PND in recent publications, we conducted a systematic and bibliometric review. The current study uses bibliometric tools to summarize the research trends and hot spots in the correlation of frailty and PND. Furthermore, we combined systematic and bibliometric to elaborate on the evidence in the fields of frailty and PND in cardiac and other surgeries patients. We hope that our findings will enhance clinicians’ and researchers’ general understanding of the evolution of this procedure and provide meaningful insight into directions relative to advances in frailty and PND.