Psychometric properties of the Thai version of the Illness-Specific Social Support Scale Short Version-8 (ISSS-8) among hematological malignancy patients in the Northeastern region of Thailand: A multicenter study.

Social support, which is an essential aspect influencing health, has resulted in the development of several approaches for assessment in cancer patients. The Illness-Specific Social Support Scale Short Version-8 (ISSS-8) effectively evaluates social support among diverse patient demographics; however, its psychometric validity has yet to be established in Asian cultural contexts. The objectives of this study were to translate and culturally adapt the ISSS-8 for the Thai setting and to assess its psychometric properties in patients with hematological malignancies (HMs). This study employed a convenience sampling method to select patients with HMs undergoing hospitalization at three tertiary institutions in Northeastern Thailand. Psychometric testing was conducted following the translation and cross-cultural adaptation of the ISSS-8 into Thai. A total of 350 patients were recruited. Participants were randomly divided into two groups for exploratory factor analysis (EFA) (n = 200) and confirmatory factor analysis (CFA) (n = 150). The EFA of the eight items yielded a loading from a two-factor model comprising Positive Support and Detrimental Interactions, which explained 82.44% of the variance. Cronbach's alpha (0.80) and item-total correlations (rho = 0.33-0.65) demonstrated acceptable reliability of the ISSS-8, while test-retest reliability was high (ICC = 0.924--0.934). The average variance extracted (AVE) demonstrated convergent validity for all ISSS-8 subscales, with AVEs ranging from 0.76 to 0.80. Moreover, the total ISSS-8 scale demonstrated a statistically significant but weak positive correlation with the Stanford Inventory of Cancer Patient Adjustment (r = 0.244, p < 0.001), while the Detrimental Interactions subscale was significantly and weak negatively correlated with it (r = 0.237, p < 0.001). These findings suggest that the ISSS-8 captures distinct psychosocial and illness-specific relational constructs that differ from coping self-efficacy and psychological adjustment measured by the SICPA. The ISSS-8 is a short, accurate, and valid instrument for measuring social support in Thai patients with HMs. As a result, healthcare professionals can use the ISSS-8 to assess social support in both research and clinical settings. The findings emphasize the necessity of integrating social support evaluation into cancer management and family-centered care, thereby supporting comprehensive and adaptive healthcare delivery in Thailand.