Frailty is a syndrome that is closely related to age. Current assessment of frailty relies mainly on single inflammatory factors or nutritional indicators and lacks systematic diagnostic markers. Chronic inflammation and nutritional status as part of the physiopathologic mechanisms of debilitation, and platelet count and nutritional status are simple and easily accessible, whereas there are fewer studies on the correlation between mixed inflammatory markers of platelet count and nutritional status and frailties.

To investigate the correlation between preoperative platelet count/albumin ratio (PAR) and new-onset frailty at 7 d postoperatively in elderly patients undergoing elective surgery.

This is a secondary study based on the Early Warning Model Construction Study of EPAE dataset. Using cross-sectional survey method was used to select elderly patients who were hospitalized and planned to undergo surgery in 7 hospitals, including the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Shunde Hospital of Guangzhou University of Chinese Medicine, the Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, the Eighth Clinical Medical College of Guangzhou University of Chinese Medicine, Huizhou Hospital of Guangzhou University of Chinese Medicine, Guangzhou University of Chinese Medicine Affiliated Zhongshan Hospital of Chinese Medicine and Dongguan Hospital of Guangzhou University of Chinese Medicine from February 2023 to October 2023. A total of 2 035 patients who were non-frailty before surgery were included, and the patients were divided into a non-frailty group (1 691 patients) and a new-onset frailty group (344 patients) according to the diagnostic criteria of the Chinese version of the Frail Scale at 7 d after surgery. General data and factors affecting perioperative frailty were collected and compared between the two groups. PAR was divided into four levels according to quartiles: Q1 (PAR≤4.160), Q2 (PAR: 4.161-5.339), Q3 (PAR: 5.340-6.479) and Q4 (PAR≥6.480), multi-model multifactorial Logistic regression analysis to assess the effect of different PAR levels on frailty. Analyzing the incidence of new-onset frailty 7 days after surgery in different age groups and receiver characteristic ROC curves were plotted to calculate the area under the curve (AUC) and the optimal cut-off value to assess the predictive value of preoperative PAR on new-onset frailty in elderly patients at 7 d postoperatively.

The age, caregiver, sedentary behavior, weekly hours of aerobic exercise, weekly hours of resistance training, proportion of stress history, age-corrected Charlson Comorbidity Index (ACCI) score, Athens Insomnia Scale (AIS) score, Depression Screening Scale (PHQ-9) score, Social Support Rating Scale (SSRS) score, American Society of Anesthesiologists (ASA) classification, preoperative analgesia, mode of anesthesia, proportion of type of surgery, duration of surgery and intraoperative transfusion were compared between the non-frailty group and the new-onset frailty group. The difference was statistically significant (P<0.05) and the PAR of the new-onset frailty group was significantly higher than that of the non-frailty group (P<0.001). The results of multifactorial Logistic regression analysis showed that after adjusting for all confounders, high level of PAR was a risk factor for new-onset frailty at 7 d postoperatively in elderly patients (OR=1.22, 95%CI=1.16-1.29, P<0.001). The results of multivariate Logistic regression analysis of different levels of PAR showed that compared with Q1 level PAR, Q2, Q3 and Q4 levels were the risk factors for new frailty at 7 days after surgery in elderly patients after adjusting for all confounding factors, and the risk of new frailty at 7 days after surgery was the highest in the Q4 group (OR=6.06, 95%CI=3.90-9.41, P<0.001). Stratified analysis showed that the incidence of postoperative new-onset frailty in different age groups increased significantly with higher preoperative PAR (P<0.001), and the AUC of preoperative PAR for predicting new-onset frailty at 7 d postoperatively in elderly patients was 0.635 (95%CI=0.606-0.665, P<0.001), and the optimal cut-off value was 4.345, with a sensitivity and specificity of 89.20% and 31.20%.

High level of PAR is a risk factor for new-onset frailty at 7 d postoperatively in elderly patients. Preoperative PAR has a certain predictive value for postoperative new frailty in elderly patients, and higher PAR indicates greater risk of postoperative new frailty.