Phase 1 Reproducibility and validity of the modified SGA
Patients and methods: The study population comprised 26 patients, 14 m en and 12
wom en of m ean (range) age, 50.4 (34-66) years, with cirrhosis of varying aetiology and severity (Table 1.3). The aetiology of the liver injury was determ ined using
Chapter 1 Assessment of nutritional status 36
historical, clinical, laboratory and histological variables, whilst the functional severity of the liver injury was assessed using Pugh’s modification of Child’s grading
system"^^.
Patients w ere assessed independently by two observers experienced in the nutritional m anagem ent of patients with chronic liver disease. The two assessments w ere undertaken within 4 days of each other using the modified SGA form at as published^^^; the data were separately recorded. N ineteen patients w ere assessed as inpatients, seven as outpatients.
Clinical information: Clinical information was obtained directly from the patients
and from their medical records. Gastrointestinal symptoms which might influence nutrient intake, such as anorexia, nausea, vomiting, difficulty in mastication, dysphagia, indigestion or food-related abdominal pain w ere recorded and graded, in relation to their degree, frequency and duration, as absent, mild, m oderate or severe. Bowel habits, and any recent changes in stool frequency, colour or consistency were recorded. A history and details of infections, renal dysfunction, hepatic encephalopathy and gastrointestinal bleeding w ere sought and detailed. Pre-illness weight and weight range in the preceding 6 months w ere recorded and the overall weight change during this period calculated. Finally, patients were questioned about recent levels of activity and fatigue to determ ine w hether their capacity for work and muscle endurance was reduced; dysfunction, when present, was further characterized in relation to its severity and duration.
Nutrient intake: The patient’s appetite was assessed as good, fair or poor and any
factors likely to interfere with food intake, for example, early satiety or taste changes were noted. Recent dietary intake was assessed using an established diet history m ethod^ supplemented, where necessary, with additional inform ation from relatives, nursing staff and food record sheets. Details of dietary restrictions and oral, enteral or parenteral nutritional support were recorded. The d ata obtained were not intended to provide a quantitative evaluation of intake but an idea of the overall adequacy of the diet in relation to estim ated requirem ents assessed using
the H arris-B enedict equations^®®. Energy intake was classified as adequate, if it m et estim ated requirem ents, inadequate, if it failed to m eet estim ated requirem ents but exceeded 500 kcal/day, or negligible if it provided less than 500 kcal daily.
Physical status: A subjective evaluation of subcutaneous fat stores - good, fair, poor
- and the presence of muscle wasting and fluid retention - none, mild to m oderate, severe - was m ade by visual inspection. Height was m easured to the nearest centim etre with patients standing in socks or bare feet, using a wall m ounted or free-standing m easure (Seca, Hamburg, Germany). Patients w ere weighed to the nearest 0.1 kg, wearing night-wear or light indoor clothing but without shoes, using a weighing scale (Seca, Hamburg, Germany) or a seat balance scale (M arsden W /M G roup, London, UK). No adjustment was m ade for fluid retention. Ideal body weight was calculated from the patients’ height based on a BMI of 22.5 kg.m'^
529
Global assessment: Each dietitian categorized the patients using the data they had
themselves collected as: (1) well-nourished;
(2) m oderately m alnourished (or suspected of being so); (3) severely malnourished.
Anthropometric validation: Once the patients had been classified using the modified
SGA, they w ere assessed anthropometrically and the data separately recorded. A n estim ated dry weight was determ ined by deducting a weight for ascites a n d /o r oedem a based on clinical assessment, previously docum ented weights and published guidelines'^. BMI was calculated from the estim ated dry weight.
MAC and TSF were measured^^’^"^^’^"^^ using H o ltain /T armer-W hitehouse skinfold calipers and a steel tape measure (H oltain Ltd, Crymych, Dyfed, UK). M easurem ents were undertaken on the non-dominant side of the body using the writing hand to define dominance unless anatom ical abnorm alities or the siting of intravenous infusions precluded m easurem ent on that side. The mid-point of the
Chapter 1 Assessment of nutritional status 38
u p p er arm was m arked betw een the acromion process of the scapula and the olecranon process while the patient held their forearm horizontally with the palm of the hand facing upwards. MAC was then m easured in a horizontal plane at the site of the m id-arm m ark with the arm hanging at full extension with the palm facing inwards. Care was taken not to distort the skin surface while the m easurem ent was made.
W ith the patient’s arm remaining in the same position, a skinfold was form ed over the belly of the triceps muscle and parallel to the humerus, using the thum b and index finger of the observer’s non-dominant hand. Care was taken not to include underlying muscle and TSF was m easured at the mid-arm m ark while continuing to hold the skinfold. Three readings were taken to the nearest 0.2 mm, 2 or 3 seconds after applying the calipers and a m ean value calculated. MAMC was also calculated^^^.
M easurem ents of MAMC and TSF were com pared with published standards for the appropriate sex and age^^ and expressed both in relation to the 5th percentile and as a percentage of the 50th percentile, described as the relative m easurem ents.
Intraobserver repeatability of anthropom etric assessment was evaluated by rem easurem ent of variables within 5 days of each other in five patients.
Statistical analysis: Statistical analysis was undertaken using the M initab software
package (1994, State College, PA, USA). Repeatability coefficients'^^ w ere calculated for anthropom etric variables for each of the observers and expressed as a percentage of the m ean of the repeated values. Interobserver agreem ent in anthropom etric m easurem ents was evaluated using the intraclass correlation coefficient, rho. Comparison of interobserver global categorization of nutrition was undertaken using the kappa statistic, a m easure of interobserver reliability that controls for the agreem ent expected by chance. Rho and kappa values betw een 0.41 and 0.60 w ere considered to indicate a m oderate association and above 0.60 to indicate a substantial relationship^^^. Spearm an rank correlations w ere used to
examine the relationships between contributing variables, including anthropom etric m easurem ents and| energy intake, and global categorization of nutrition. C orrelation coefficients above 0.39 were considered to indicate a significant association for the sample of 26 patients at the 5% levef^^.
Results: There was agreem ent between observers in the nutritional status of 21
(81%) of the 26 patients using the modified SGA (kappa = 0.67). W here there was discordance, it was by a single category and without bias.
The intraobserver repeatability coefficients for anthropom etric variables ranged from zero to 8.0% (Table 1.4).
All anthropom etric variables showed excellent interobserver agreem ent with intraclass correlation coefficients exceeding 0.8 (Table 1.5). T here was m oderate agreem ent between evaluation of energy intake (rho = 0.42).
C orrelation between the SGA and BMI, relative TSF and relative M AM C yielded r values of -0.30, -0.48 and -0.53 respectively (Table 1.5).
Thus, the modified SGA m ethod of assessment was reproducible betw een two observers, and significantly associated with relative TSF and relative MAMC. However, it did not take explicitly into account anthropom etric m easurem ents which are considered useful in providing quantitative estim ates of body composition. Concerns have been raised about the use of subjective assessment alone in this patient population as it fails to identify as m alnourished some individuals with depleted anthropometric measurements^^^.
Therefore, in order to develop an improved assessment scheme, three objective variables - BMI, relative TSF and relative MAMC - w ere incorporated. These variables related significantly to the modified SGA and all had high interobserver
Chapter 1 Assessment of nutritional status 40
Fhas^ 2 D erivation of New G lobal Assessment Tool
Patients and methods: A n assessment scheme was devised to categorize nutritional
status in patients with chronic liver disease on a semi-structured basis determ ined by a com bination of subjective data and the three objective variables.
D ata w ere collected on gastrointestinal and other clinical symptoms, nutrient intake and physical status. Height, weight, MAC and TSF were m easured, dry weight estim ated and, from these, BMI, MAMC, relative MAMC and relative TSF were calculated. All the findings and m easurem ents, together with derived variables and dem ographic and clinical information, were collected as described above but docum ented on a single data collection form.
Patients w ere then categorized using the BMI, relative TSF, relative M AM C and nutrient intake data on an algorithmic basis as (Figure 1.1):
(1) well-nourished;
(2) m oderately malnourished (or suspected of being so); (3) severely malnourished.
A subjective override was incorporated, based on the other data collected, to allow factors, such as profound recent weight loss, severe steatorrhoea or aggressive nutritional intervention which may effect nutritional status, to be taken into account. This override allowed the assessor to change nutritional class by one category only.
In the first assessment of this phase, one observer assessed a group of patients and docum ented all relevant data on anonymized collection sheets w ithout recording the derived nutritional categorization. The second observer then reviewed the data sheets and categorized the patients’ nutritional status on the basis of the recorded inform ation only; no access was allowed to the patients or their m edical records.
The study population comprised 150 patients (87 men: 63 women; m ean age 50.7 [26-75] years) with cirrhosis of varying aetiology and severity (Table 1.3). One hundred and nine (73%) patients were assessed as inpatients, 41 as outpatients.
Comparisons w ere made between global categorization of nutritional status by the two observers using the kappa statistic, Spearm an rank correlations w ere used to examine the relationship between contributing variables and global categorization.
Results: There was agreem ent in the categorization of nutritional status in 145
(97% ) of patients using the devised scheme yielding a kappa value of 0.94 for the whole group. W here discordance occurred it was by a single category; four patients w ere categorized as m ore m alnourished by the first observer and one by the second. The degree of agreem ent varied little in subgroups divided on the basis of gender, aetiology or severity of liver disease (kappa = 0.88-1.00) (Table 1.6). The relationships between the global categorization and BMI, relative TSF and relative MAMC yielded r values of -0.69, -0.47 and -0.68 respectively.
Com pared to the modified SGA, the new Royal Free Hospital global assessment scheme (R FH GA) provided an improved interobserver categorization of nutritional status which was more closely associated with BMI and relative MAMC. Based on these results, the assessment scheme was modified by excluding relative TSF from the algorithm for the next phase.
Phase 3 Reproducibility and validity o f the devised global assessment R FH G A m ethod
Patients and methods: The study population comprised 50 patients, 34 m en and 16
wom en of m ean (range) age 50.1 (27-70) years with cirrhosis of varying aetiology and severity assessed as previously (Table 1.3). All were inpatients at the Royal F ree H ospital at the time of assessment.
All patients were assessed by two observers working independently without exchange of objective or subjective data other than the nam e and location of the patients in the study. Assessments were undertaken within 7 days of each other. The data collected were used to determ ine nutritional status using the modified algorithm of the R F H GA (Appendix).
Chapter 1 Assessment of nutritional status 42
The data were analysed as described in Phase 1. W here the subjective override had been employed to change the final category of nutritional status, the factors influencing the decision were examined using unpaired Student’s t-tests and Chi- squared analyses.
Results: There was agreem ent in the categorization of nutritional status in 44
(88%) of the 50 patients (kappa = 0.79). W here discordance occurred it was by a single category with four patients categorized as m ore m alnourished by the first observer and two by the second.
Excellent interobserver agreem ent was observed for BMI and relative MAMC (rho = 0.93 and 0.90). The correlation between global categorization and BMI and relative MAMC yielded r values of -0.78 and -0.69 respectively (Table 1.7).
The subjective override was employed in 9/50 and 8/50 of the patients by the two observers respectively. In only one patient was the override: used by both observers. Thirteen patients were categorized as m ore m alnourished than previously while four were categorized as less malnourished. Patients categorized as m ore m alnourished had a greater m ean weight loss and reported more symptoms than those who were categorized as less m alnourished although in neither instance was the difference significant. As a consequence of using the override, agreem ent in categorization was achieved in 11 patients which had previously been discordant, while in the remaining five patients the override changed agreem ent in categorization to discordance.