The association between malnutrition and postoperative complications, and the potential for prevention of both

Abstract

Introduction: Poor nutritional status is an established risk factor for suboptimal outcome of hospital stay, including among other things, an increased risk of postoperative complications. Despite the fact that international guidelines for surgery acknowledge this, they do not tell how to identify or prevent and treat malnutrition, and neglected malnutrition at hospitals has been reported for years. During the past two decades, there has been an increased focus on nutritional care in hospitals as a part of both local and national patient’s safety work. In this respect, screening patients for being “at risk of malnutrition” and further assessment of these patient’s nutritional status is recommended. Notably, the impacts of the diagnostic criteria on the incidence of postoperative complications, and the effect of implementation of nutritional guidelines on nutritional care at hospitals are scarcely investigated. To explore these relationships, a selection of established quality registers can be used.

Objectives: The overall objective of this thesis was to investigate the association between malnutrition and postoperative complications, and the potential for prevention of both. The specific objectives of the following papers was to investigate: I. The association between «at risk of malnutrition» and the incidence of surgical site infection in a mixed surgical patient sample at a large university hospital. II. The prevalence of preoperative malnutrition, and its association with severe postoperative complications and death among patients undergoing gastrointestinal resections at Norwegian hospitals. III. Whether the increased nutritional policy investment has resulted in changes in the prevalence of patients being «at risk of malnutrition», use of nutritional support and related diagnosis codes during an 11-year period at a large university hospital, and if there remains a further potential to decrease the risk of both malnutrition and postoperative complications.

Methods: To evaluate the prevalence and associations between malnutrition and postoperative complications (Paper I and Paper II), we used data from local and national registry databases: 1) The Malnutrition registry and 2) The local NOIS-POSI database (NOIS, Norwegian Surveillance System for Health Care Associated Infections in Hospitals; POSI, postoperative site infection) at Haukeland University Hospital, and 3) The Norwegian Registry for Gastro Surgery (NoRGast). The Malnutrition registry was also used to evaluate the trends in compliance with nutritional guidelines in the period 2008 - 2018 (Paper III). Results: We found the incidence of surgical site infections in a large Norwegian university hospital to be positively associated with the prevalence of «at risk of malnutrition» (OR 1.81 (95 % CI: 1.04 - 3.16)) (Paper I). Moreover, we found 35.4 % of patients at Norwegian hospitals having gastrointestinal surgery to be malnourished (Paper II). These patients were 1.29 (95 % CI: 1.13 - 1.47) times more likely to develop severe postoperative complications, and 2.15 (95 % CI: 1.27 - 3.65) times more likely to die within 30 days, as compared to those who were not. We observed no change in the prevalence of «at risk of malnutrition» in the period 2008 – 2018 at a large Norwegian university hospital (Paper III). However, more patients received nutritional support (from 61.6 % in 2008 to 71.9 % in 2018 (p < 0.001), with a range from 55.6 to 74.8 %). This trend was seen for both surgical and non-surgical patients (p < 0.001). Also, there was an increasing trend of having a dietitian involved in the patient care and using a related diagnosis code for patients “at risk of malnutrition”, despite less common for surgical, as compared to non-surgical patients (p < 0.001).

Conclusions: This thesis demonstrated that patients identified to be «at risk of malnutrition» or malnourished by recommended screening tools have an increased risk of postoperative complications as compared to those who are not. Despite a higher percentage of patients “at risk of malnutrition” received nutritional support, each year of the study period, one of four patients «at risk of malnutrition» did not receive nutritional support, and fewer surgical, as compared to non-surgical patients, received support from a dietitian or had a related diagnostic code at admission. This indicates that there is still a potential to reduce the risk of malnutrition on surgical patients, something that should be investigated in well-designed randomized controlled trials in the future.