Impact of preoperative nutritional support on clinical outcome in abdominal surgical patients at nutritional risk

Abstract

Objective

This multicenter, prospective cohort study evaluated the effect of preoperative nutritional support in abdominal surgical patients at nutritional risk as defined by the Nutritional Risk Screening Tool 2002 (NRS-2002).

Methods

A consecutive series of patients admitted for selective abdominal surgery in the Peking Union Medical College Hospital and the Beijing University Third Hospital in Beijing, China were recruited from March 2007 to July 2008. Data were collected on the nutritional risk screening (NRS-2002), the application of perioperative nutritional support, surgery, complications, and length of stay. A minimum of 7 d of parenteral nutrition or enteral nutrition before surgery was considered adequate preoperative nutritional support.

Results

In total 1085 patients were recruited, and 512 of them were at nutritional risk. Of the 120 patients with an NRS score at least 5, the complication rate was significantly lower in the preoperative nutrition group compared with the control group (25.6% versus 50.6%, P = 0.008). The postoperative hospital stay was significantly shorter in the preoperative nutrition group than in the control group (13.7 ± 7.9 versus 17.9 ± 11.3 d, P = 0.018). Of the 392 patients with an NRS score from 3 to 4, the complication rate and the postoperative hospital stay were similar between patients with and those without preoperative nutritional support (P = 1.0 and 0.770, respectively).

Conclusion

This finding suggests that preoperative nutritional support is beneficial to patients with an NRS score at least 5 by lowering the complication rate.

Introduction

Preoperative malnutrition is common in surgical patients and has been associated with poor clinical outcomes [1]. A study by the Veterans Affairs Administration has shown that preoperative parenteral nutrition decreases the rate of complications in severely malnourished patients but not in borderline or mildly malnourished patients [2]. A meta-analysis was performed of 13 prospective randomized trials in which most subjects were at least moderately malnourished according to weight loss, plasma proteins, or prognostic indices. Five trials found significantly fewer postoperative complications in patients who received preoperative nutritional support, and the pooled results indicated that total parenteral nutrition (TPN) therapy decreased the overall risk of postoperative complications by approximately 10% [3]. Although these studies were criticized for inadequate sample sizes, imprecise definitions of complications, and diverse definitions of malnutrition, there was a consensus that the effectiveness of preoperative nutrition was confined to a limited group of patients with severe malnutrition [4], [5].

The search has continued for more accurate methods of preoperative nutritional assessment and for better identifying the specific subsets of patients who might be best served by preoperative nutritional support. Kondrup et al. [6] established the Nutritional Risk Screening Tool 2002 (NRS-2002), which was validated against 128 previous trials of nutritional support and clinical outcomes from the literature. The results from the validation study showed that artificial nutritional support was associated with positive outcomes such as a lower complication rate in patients at nutritional risk [6]. Furthermore, prospective cohort studies have shown that patients at nutritional risk as defined by the NRS-2002 are more likely to have unfavorable clinical outcomes and nutritional support improves outcomes in such patients [7], [8]. The NRS-2002 was recommended by the Europe Society of Parenteral and Enteral Nutrition for use in hospitalized patients [9].

However, there have been no studies on the effect of preoperative nutritional support in patients at nutritional risk as defined by the NRS-2002. A randomized controlled trial would be the best study design, but assigning parenteral and enteral nutrition randomly to patients at severe nutritional risk raises ethical concerns. Therefore, we conducted this multicenter, prospective cohort study to evaluate the impact of preoperative nutritional support on clinical outcomes in patients at nutritional risk. The primary endpoint was the complication rate and the second endpoint was the length of stay (LOS). The protocol was carried out in teaching hospitals in Beijing, China.