Several studies have shown that age is a relevant factor for complications in liver surgery (Trundle et al. 2019; Laporte and Kalil 2013). With increasing age, the complication rate of liver surgery has gradually increased (Liu et al. 2021). A study of 663 patients who underwent hepatectomy showed that the 90-day mortality rates were 11.0%, 13.0%, and 17% for patients aged > 70, 75, and 80 years, respectively, and that the complication rates were 53%, 57%, and 66%, respectively (Shutt et al. 2016). Therefore, establishing a liver surgery complication evaluation system for older persons and dealing with the risk factors for complications are important.

Although advances in surgical techniques and perioperative management have reduced the incidence of complications and the mortality rate after hepatectomy during the last half century, liver failure after major hepatectomy has remained an important problem (Ocak et al. 2020). Before the 1980s, the mortality rate related to hepatectomy was approximately 10%. In recent years, however, the mortality rate has decreased to < 1% in some surgical centers, and several recent studies have reported a mortality rate of 0 (Huang et al. 2009). The incidence of liver failure after hepatectomy varies greatly in the reported literature, and the generally accepted incidence is between 8 and 12% (Søreide and Deshpande 2021). Liver failure after hepatectomy is the most common cause of death after liver surgery, and a decrease in liver function in older persons before surgery may be one of the reasons for this situation (Lodewick et al. 2017). Therefore, a detailed preoperative assessment of liver function is important. The Child–Pugh grade is the most widely used indicator of liver function (Huang and Gao 2020). This study showed that Child‒Pugh grade B was an independent risk factor for postoperative complications in older persons (aged ≥ 75 years).

The residual liver volume after hepatectomy is a key predictor of perioperative outcomes (Simpson et al. 2014). It is closely related to various barriers, including postoperative ascites, bleeding, and wound healing (Blüthner et al. 2020). The residual liver volume can be used to predict the risk of liver failure in patients undergoing hepatectomy (Olthof et al. 2019). Although the etiology of liver failure after hepatectomy is multifactorial, insufficient residual liver volume is considered to be the most important modifiable predictor. Preoperative assessment of residual liver function and volume is essential before liver resection (Khan et al. 2018). Unless the remaining liver after hepatectomy has a sufficient volume, surgery may lead to liver dysfunction, which may, in turn, lead to further postoperative complications. With increasing age, liver volume and blood flow are significantly reduced. In addition, the liver reserve function of older patients is significantly decreased, which reduces their tolerance to liver disease treatment (Tajiri and Shimizu 2013). This study showed that ≥ 3 liver segments removed was an independent risk factor for complications after hepatectomy in older persons (aged ≥ 75 years). Similarly, many studies have shown that the larger the scope of an operation is, the more complications there are. This study also showed that patients with extrahepatic organ invasion had a greater risk of complications if organ resection was performed simultaneously.

Frailty is an independent predictor of a high incidence of postoperative adverse events (Shinall et al. 2020). Frailty symptoms in elderly patients should be evaluated, and geriatricians should be consulted for further evaluation if necessary (Ko 2019).

Accurate assessment of frailty in elderly people can help individuals identify high-risk groups as early as possible, predict adverse health outcomes, and provide a reference for further assessment, treatment, and nursing measures for elderly people with different degrees of frailty. In addition, accurate assessment of frailty in perioperative elderly patients can guide doctors in controlling the safety of perioperative procedures. Frailty is associated with poor surgical outcomes and poor prognosis (McIsaac et al. 2017). The risks of surgery and perioperative complications are increased in older people with frailty. Beggs et al. (Beggs et al. 2015) analyzed 19 studies on frailty and perioperative outcomes and found that although the evaluation criteria and types of surgery were different, frailty was associated with perioperative adverse outcomes to some extent. Frail patients have higher mortality, morbidity, and complications; longer hospital stays; and slower recoveries after discharge than nonfrail patients (Makary et al. 2010).

Comorbidities and fatigue are the main conditions used to assess frailty (Church et al. 2020; Thompson et al. 2020). Many patients who require surgery often have one or more other medical conditions, termed comorbidities (Couri and Pillai 2019). Comorbidities are common in elderly individuals and can affect disease manifestation and severity, sometimes even impacting management (Scichilone 2017). Old age, therefore, is associated with a number of age-associated risks and remains the most common predisposing factor for poor postoperative outcomes (Olotu 2021). With the development of traditional surgery, a large number of high-risk surgery patients with single/multiple-organ dysfunction have undergone surgery, and the number of surgical patients with atherosclerosis, diabetes, chronic obstructive pulmonary disease, and other internal diseases has increased rapidly. Fatigue is also significantly related to postoperative adverse events. This study also showed that ≥ 5 kinds of comorbid diseases and fatigue were independent risk factors for postoperative complications in older persons (aged ≥ 75 years).

One study used the abnormal skeletal muscle mass index, type of surgery, and preoperative serum albumin concentration to develop a risk-scoring system for liver surgery in older persons (Tomita et al. 2021). When the risk score of this scoring system was ≤ 1, the postoperative complication rate was 0.0%; when the risk score was ≥ 4, the postoperative complication rate was 57.1%, and the AUC was 0.810. However, at present, abnormal skeletal muscle mass indices are not routinely detected by this evaluation method in clinical practice, which makes this evaluation system unsuitable for widespread use.

The items of RASHA established in this study are easy to obtain clinically, and RASHA has not only a score (RASHA scale) but also a risk probability (RASHA formula), which makes the evaluation results more intuitive. In addition, our research focused on the conditions of older persons, including fatigue, comorbidities, and other factors related to frailty. Therefore, RASHA is more effective at assessing surgical risk in older patients.

Accurate assessment of frailty in older patients during surgery can guide doctors in controlling the safety of surgery. Because short and simple instruments are most feasible in clinical practice, several quick screening tools have been developed and validated. However, these scales have the disadvantages of complicated evaluation processes and difficult data acquisition, which limit their clinical application. For example, the FRAIL scale consists of five items: fatigue, resistance, aerobic, illness, and loss of weight. However, obtaining a specific weight loss and walking distance (resistant or aerobic) is difficult, which limits the application of the FRAIL scale. Therefore, this study used fatigue and comorbidities to reflect the state of frailty. However, if a patient’s frailty can be assessed with a widely recognized frailty assessment tool, the patient's frailty state can be better assessed.