Reliability and validity of the 23-Duke Social Support Scale among rural elderly population

Objective To assess the reliability and validity of 23-Item Duke Social Support Index(DSSI-23)scale among an elderly population in rural areas.Methods Stratified random cluster sampling was employed to select 1021 elderly people aged ≥60 years and without severe hearing disorders or mental problems from rural areas in Zigong and Guangyuan municipality of Sichuan province and the participants were surveyed face-to-face with DSSI-23 scale.Reliability of DSSI-23 was evaluated by split-half reliability and Cronbach's α coefficient.Validity of DSSI-23 was evaluated by convergent,discriminant,and structure validity.Results The split-half reliability coefficient was 0.910 and the overall Cronbach's α coefficient was 0.873.The Cronbach's α coefficient for domains of social interaction,subjective social support,utilization of social support were 0.459,0.855,and 0.888,respectively;after deleting items for one of the 3 domains successively,the overall Cronbach's α were 0.891,0.803,and 0.808(all >0.8).The DSSI-23 scale has good reliability.The correlation coefficient of each item with the total scale(except the item 3)was 0.35-0.69(P<0.01).The DSSI-23 scale has good convergent and discriminant validity,with the success rate of calibration experiment of 100% for both convergent and discriminant validity.The structure validity was tested by confirmatory factor analysis and the fitness indexes were 0.082 for root mean square error of approximation(RMSEA),0.837 for goodness-of -fit index(GFI),0.807 for normed fit index(NFI),0.827 for comparative fit index(CFI),and 0.828 for incremental fit index(IFI),respectively.Significant differences were observed in the scores for social interaction and subjective social support among the elderly at various ages and in the scores for social interaction,subjective social support,utilization of social support,and the whole scale among the elderly with different education level and marital status(all P<0.05),suggesting that DSSI-23 scale has good discriminant validity.Conclusion The DSSI-23 scale has good reliability,convergent validity,and discriminant validity but dissatisfactory structure validity when measuring social support among elderly population in rural area,suggesting some items of the scale need to be revised.