Anthropometric characteristics, high prevalence of undernutrition and weight loss: impact on outcomes in patients with adolescent idiopathic scoliosis after spinal fusion.

PURPOSE: Abnormal anthropometry including comparably lower weight and body mass index (BMI) in the adolescent idiopathic scoliosis (AIS) population is increasingly recognised, however, no study has examined postoperative weight loss or its clinical relevance in these relatively thin patients. This study aimed to assess perioperative nutritional status as well as clinically severe involuntary weight loss and its impact on outcomes in patients with AIS undergoing posterior spinal fusion (PSF). A further objective was to compare preoperative anthropometric measurements of the current AIS cohort with healthy controls.
METHODS: Seventy-seven consecutive and eligible patients with AIS who underwent PSF were prospectively followed up from hospital admission (January 2010-April 2012). Pre- and postoperative anthropometric measurements were collected (weight, height, BMI), and clinically severe unintentional weight loss computed, defined as loss of >10% body weight from admission to hospital discharge. The effect of weight loss >10% was analysed in relation to radiographic, nutritional and perioperative complication data, and length of hospitalisation. A case-controlled study was then performed to establish potential differences in weight, height and BMI of this AIS cohort with healthy age- and gender-matched controls derived from the National Teens' Food Survey (2005-2006). Anthropometric values were standardised by conversion to age- and gender-specific Z-scores; 'undernutrition' was defined as BMI Z-scores <-2.
RESULTS: Mean age of the cohort was 15 years (SD 1.89); 93.5 % of subjects were female. Clinically severe postoperative weight loss >10%, identified in 22 patients (30.6%), was associated with a significantly increased superficial wound infection incidence (13.6 vs. 2%, P = 0.047), as well as lower serum albumin at hospital discharge (25 vs. 28 g/L, P < 0.05). A high prevalence of postoperative undernutrition was observed-over one quarter of patients had a BMI Z-score <-2 at hospital discharge (26.4%); serum albumin, total protein and haemoglobin levels were below normal limits in 98, 66 and 91% of patients, respectively. Significantly lower weight (52 vs. 59.8 kg, P < 0.0001), corrected height (162 vs. 166.3 cm, P < 0.0001) and BMI (19.72 vs. 21.6 kg/m(2), P < 0.0001) measurements were identified in this AIS cohort, in comparison with those recorded in The National Teens' Survey.
CONCLUSIONS: This study demonstrated that clinically severe postoperative weight loss >10%, identified in almost one-third of this AIS cohort, was associated with significantly increased wound infection incidence. Early detection and prevention of severe postoperative weight loss in patients with AIS who undergo spinal fusion may be beneficial in reducing wound infection risk. This study confirms a body of literature indicating the significantly lower weight and BMI in patients with AIS compared with healthy controls.