Introduction

An aging population model leads to a systematic increase in the number of elderly individuals undergoing surgical procedures. Geriatric patients are characterized by increased susceptibility to postoperative complications, resulting from the presence of comorbidities and the frequent occurrence of nutritional disorders. Malnutrition, including inadequate protein intake, represents a significant yet potentially modifiable problem and constitutes a risk factor for numerous postoperative complications and delayed recovery.

Protein plays a crucial role in wound healing, tissue regeneration, and the maintenance of muscle mass and strength, which is particularly important given that elderly people experience a physiological decline in muscle mass and reduced anabolic sensitivity, thereby increasing protein requirements. This is especially relevant in situations of metabolic stress, such as surgical procedures. Protein deficiency may lead to the exacerbation of sarcopenia, prolonged recovery, increased incidence of perioperative infections, and other complications.

In recent years, numerous studies have shown that impaired nutritional status, assessed using indices such as the Geriatric Nutritional Risk Index (GNRI) or the Prognostic Nutritional Index (PNI), is associated with a significantly higher risk of postoperative complications, prolonged hospital stay, and increased perioperative mortality in elderly patients.

The GNRI is calculated using the following formula: 1.489 × serum albumin concentration (g/L) + [41.7 × current body weight (kg) / ideal body weight (kg)]. For men, ideal body weight is calculated as 0.75× height (cm) – 62.5; whereas for women the formula 0.60× height (cm) – 40 is used. Based on the obtained GNRI values, patients can be classified into four categories: no nutritional risk (GNRI > 98), mild risk (GNRI 92–98), moderate risk (GNRI 82–91), and severe risk (GNRI < 82) [1].

The PNI is calculated using a formula based on serum albumin and lymphocyte levels: serum albumin concentration (g/L) + 0.005 × total lymphocyte count (× 10⁹ /L). Patients were divided into three groups: normal nutritional status (PNI > 38), moderate risk of malnutrition (PNI 35–38), and severe risk of malnutrition (PNI < 35) [4].

These observations were confirmed in both elective and emergency surgical procedures. Although these indicators do not directly measure protein intake, they provide a reliable indirect reflection of inadequate nutrient supply, including protein.

The clinical significance of this issue is particularly important, as the assessment of nutritional status and optimization of protein intake prior to surgery may represent simple interventions that, in the long term, are beneficial for both the patient and the hospital. A reduced risk of postoperative complications and faster recovery are associated with lower healthcare costs.

Despite the growing number of publications, data on the direct impact of protein intake on postoperative outcomes in elderly people remain limited and require further systematization.

Aim of the study

The aim of this review paper is to analyse publicly available studies evaluating the relationship between low protein intake and poor nutritional status in elderly people and the risk of postoperative complications and the course of recovery, with particular emphasis on the role of nutritional indicators used in clinical practice.

Material and methods

This study was conducted as a literature review aimed at analysing the relationship between nutritional status in elderly patients—associated with dietary protein intake—and the risk of postoperative complications and the course of recovery. The review was performed using the PubMed medical database.

The publications used in this study concerned patients aged ≥65 years undergoing surgical treatment. Combinations of keywords related to nutritional status and postoperative outcomes were applied, including: elderly, protein intake, malnutrition, nutritional status, postoperative complications, surgical outcomes, Prognostic Nutritional Index, and Geriatric Nutritional Risk Index.

Six original observational or cohort studies were included in the review, in which patients’ nutritional status was assessed preoperatively using the Geriatric Nutritional Risk Index (GNRI) and/ or the Prognostic Nutritional Index (PNI). The analysis focused on the association between nutritional status in geriatric patients and postoperative outcomes. Inclusion criteria were: an elderly population aged ≥65 years, assessment of nutritional status in the preoperative period, and reporting of at least one clinically relevant endpoint, such as the incidence of postoperative complications, perioperative mortality, length of hospital stay, or rate of recovery. Data from the included studies were analyzed qualitatively, with emphasis on the direction and strength of the observed associations between impaired nutritional status and postoperative course.

Review articles, case reports, studies involving pediatric populations or adults under 65 years of age, and publications lacking clear data on postoperative outcomes were excluded from the analysis.

Results

The analysis of the six cited scientific studies demonstrated an association between impaired nutritional status in elderly patients and poorer surgical outcomes. In all analyzed studies, patients with a GNRI score ≤98 and/or a PNI score ≤38 had a significantly higher incidence of postoperative complications compared with those with normal nutritional status (Tab. 1).

In studies assessing the incidence of perioperative infections, patients with reduced nutritional index values were found to more frequently experience surgical site infections, pneumonia, and urinary tract infections. Moreover, patients with poorer nutritional status demonstrated an increased risk of complications such as cardiorespiratory failure, as well as impaired wound healing and scar formation (Tab. 2).

In most of the analyzed studies, an association was also demonstrated between impaired nutritional status and prolonged length of hospital stay following surgery. Patients at risk of malnutrition (low GNRI and/or PNI) required longer hospital treatment and were characterized by a poorer postoperative course and significantly higher mortality. Poorer preoperative nutritional status was associated with delayed recovery and a greater postoperative burden [2, 3, 5, 6, 7] (Tab. 3).

Some of the analyzed studies further indicated a significant association between reduced nutritional status and increased perioperative mortality. This relationship persisted even after adjusting for other risk factors, such as age, comorbidities, and the extent of the surgical procedure. These findings clearly suggest that nutritional status constitutes an independent prognostic factor in the geriatric patient population [4, 5, 6, 7].

Although none of the included studies directly analysed the amount of protein intake, the nutritional status indicators used (GNRI, PNI) indirectly reflected its deficiency. Across all studies, patients with lower values of these indices achieved poorer postoperative outcomes, suggesting the potential importance of adequate protein intake in the perioperative period.

Discussion

The results of the analysed studies indicate a significant association between impaired nutritional status in older adults and a poorer postoperative course. Elderly patients at risk of malnutrition were shown to experience postoperative complications more frequently, had longer hospital stays, and demonstrated slower recovery. These findings highlight the importance of nutritional status as a significant prognostic factor in the surgical treatment of the geriatric population [3, 4, 5, 6, 7].

Particular attention should be paid to the fact that although none of the analyzed studies focused directly on the amount of protein intake, all of them used nutritional indices that indirectly reflect its deficiency. Protein plays a key role in the body’s response to surgical stress, and insufficient protein intake may limit the ability to regain functional capacity after surgery.

The findings regarding the increased incidence of perioperative infections in patients with poorer nutritional status are consistent with current knowledge about the impact of malnutrition on immune system function. This, in turn, leads to prolonged hospitalization and a worse prognosis. Clinically significant are also the observations concerning delayed wound healing and impaired scar formation, which may reduce patients’ quality of life after surgery [2, 3, 5].

From a clinical practice perspective, it is particularly important that the assessment of nutritional status prior to a planned surgical procedure represents a tool that is relatively easy to implement. Indices such as GNRI or PNI can be calculated on the basis of routinely performed laboratory tests and anthropometric measurements. This enables early identification of patients at increased risk of complications and creates an opportunity to introduce nutritional interventions before surgery. Potential optimization of protein intake in the preoperative period may constitute one of the elements contributing to improved surgical outcomes in older adults.

The limitations of this review should also be emphasized. First, the cited studies were observational in nature, which precludes the establishment of clear cause-and-effect relationships. Moreover, the nutritional indices used allowed only for an indirect, rather than direct, assessment of the amount and quality of protein intake. The heterogeneity of the studied populations, types of surgical procedures, and evaluated endpoints further limits the possibility of direct comparison of the individual study results.

Despite these limitations, the obtained results clearly indicate that nutritional status—and indirectly, protein intake—plays a significant role in shaping postoperative outcomes in geriatric patients. Further prospective studies are necessary to directly assess the impact of the quantity and quality of protein intake on the risk of complications and the rate of recovery in this patient population. Such an approach could contribute to the development of more precise nutritional recommendations for the perioperative period.

Conclusions

Based on the conducted literature review, it can be concluded that the nutritional status of geriatric patients plays a significant role in determining surgical outcomes. Older adults with features of malnutrition or increased nutritional risk more frequently experience an unfavourable postoperative course, including a higher incidence of complications and prolonged hospitalization. These observations indicate that impaired nutritional status constitutes an important risk factor in this group of patients.

Available data also suggest that patients with poorer nutritional status are more likely to develop perioperative infections and require longer hospital stays, which may indirectly indicate a slower postoperative recovery. In this context, preoperative assessment of nutritional status using indices such as the Geriatric Nutritional Risk Index or the Prognostic Nutritional Index appears to be a simple and useful prognostic tool, enabling the identification of patients at increased risk of postoperative complications.

Although the analysed studies did not include a direct assessment of protein intake, the obtained results indicate that insufficient protein supply may play a significant role in impairing the adaptive capacity of older adults in response to surgical stress. Early evaluation of nutritional status and the implementation of nutritional interventions in the preoperative period may therefore constitute an important component in improving surgical outcomes in the geriatric population.