Translation, cross-cultural adaptation, and validation of the Scored Patient-Generated Subjective Global Assessment (PG-SGA) as a nutrition assessment tool in Thai cancer patients
Authors:   , Nitichai Nicharach 
Published: September 2023

The Scored Patient-Generated Subjective Global Assessment (PG-SGA) is a multidimensional tool to assess malnutrition and risk factors. At present, there is no official Thai translation and cultural adaptation of the PG-SGA available. Health professionals should be able to obtain and utilize valid and reliable tools matched with their own languages and cultures to further produce high quality patient care. The primary objective of this study is to translate and culturally adapt the original PG-SGA for the Thai setting and evaluate perceived comprehensibility, difficulty, content validity and intra-rater reliability of the Thai PG-SGA in cancer patients and healthcare professionals. In addition, this study aimed to determine the validity of the Thai version of the Scored PG-SGA and examine the correlations between clinical variables and nutritional instrument tools. The study consists of two parts. In the first part, the PG-SGA was translated and culturally adapted using the International Society for Pharmacoeconomics and Outcomes Research Principles. In 50 cancer patients and 50 healthcare professionals, perceived comprehensibility and difficulty of the Thai PG-SGA were assessed with the Scale Comprehensibility Index (S-CI) and Scale Difficulty Index (S-DI), using a 4-point scale. Content validity, i.e. relevance, was assessed in the professionals only, by Scale Content Validity Index (S-CVI). Intra-rater reliability (test-retest within 72 hours of admission) was tested by the Intraclass Correlation Coefficient (ICC) and weighted kappa (κ). In the second part, 195 cancer patients were enrolled to the study. Nutritional status assessed by the Thai PG-SGA and Subjective Global Assessment (SGA), anthropometry, dietary intake, handgrip strength and laboratory data were collected. The results revealed that the systematically translated Thai version of PG-SGA needed 4 cultural adaptations. It showed excellent comprehensibility (S-CI=0.99) and difficulty (S DI=0.95) as perceived by patients. It also showed excellent comprehensibility (S-CI= 0.92) and borderline acceptable difficulty (S-DI=0.79) reflected by professionals. Its relevance in assessing malnutrition was excellent (S-CVI=0.95). Agreement between numerical scores was good to excellent (ICC=0.95), and between PG-SGA categories was very good (κ=0.95). The Thai PG-SGA had high sensitivity (99%), specificity (86%) and accuracy (93%) compared to SGA. The prevalence of malnutrition assessed by using the Thai PG-SGA was 62%. It had perfect agreement with SGA in classification of nutritional status. In addition, the nutritional status by each instrument was correlated with anthropometric parameters, body fat, laboratory parameters, dietary intake and hand grip strength (p < 0.05). In conclusion, the Thai version of the PG-SGA is now available and considered very easy to complete by patients, very comprehensible and relevant by professionals, and as borderline acceptable regarding difficulty to complete. It is a valid and reliable nutrition instrument tool in predicting malnutrition among cancer patients.