With the rapid growth of the number of older adults in industrialized countries, the harmful effects of loneliness have been identified in animal models and human longitudinal surveys.1 In 2018, the Lancet reported that loneliness is becoming a public health problem.1 In recent years, due to the development of urbanization in China, the shrinking of the family structure, the tendency of young people to work away from home, and communication methods for networking, the level of loneliness of the older adult population in China has gradually increased.2 The loneliness of older adults leads to an increasingly serious social and economic burden caused by psychosomatic disorders.3

The feeling of loneliness is multilayered and multidimensional.4 Peplau defined loneliness as an unpleasant subjective experience when individuals feel a lack of satisfactory interpersonal relationships and a gap between the ideal level of social interaction and reality, a negative emotional state.5 Weiss distinguishes between social loneliness and emotional loneliness.6 Social loneliness refers to a lack of social networks and social integration, while emotional loneliness is related to the loss of personal attachment figures.4 Studies on loneliness among older adults showed that approximately 9% of older adults reported severe loneliness in the UK,7 and 17.1% of older adults reported loneliness for most of the past week in the US.8 A national longitudinal study in China found that 30.6% of older women reported loneliness, compared to 22.9% of older men.9 In addition, studies have shown that loneliness increases the risk of heart disease, stroke, Alzheimer's disease, and dementia in older adults,9, 10, 11 and loneliness has been associated with anxiety, depression, decreased functioning, sleep disturbances, and increased mortality.12,13 Thus, loneliness is a global health problem that requires social and medical support.1

Currently, there are many varied scales used to assess loneliness in older adults, such as the UCLA loneliness scale (UCLA), the de Jong Gierveld loneliness scale (DJGLS), the differential of loneliness scale (DLS), the loneliness rating scale (LRS), and the adult social and emotional loneliness scale (SELSA).14, 15, 16, 17, 18 However, none of these scales were developed specifically for older adults. Among them, the most widely used is the UCLA loneliness scale, but it focuses more on the social dimension of loneliness and lacks attention on the family dimension. Older adults, as a vulnerable group of lonely people, have been an important subject of research in the field of loneliness. Due to older adults' unique physical and mental status, few scholars have developed scales that address the characteristics of loneliness in older adults. In addition, research related to multidimensional loneliness is also lacking in China. Therefore, BANDARI developed the loneliness scale for older adults (LSOA).19 First, the scale classifies loneliness into five factors. Then, the scale uses simple language and a moderate number of items, which is suitable for use by older adults. However, the scale has not been used and tested in the Chinese older adult population; thus, the suitability of the scale for detecting loneliness in the Chinese cultural context needs to be studied.

This study aims to translate the LSOA from English into Chinese and evaluate its psychometric properties among older adults in Chinese communities. After evidence of the scale's consistent internal reliability regarding our hypothesis, confirmatory factor analysis (CFA) will be used to test reliability and validity and concurrent validity by comparing the LSOA with the UCLA measure. Evidence of a reliable and valid measure of loneliness for older Chinese adults will help evaluate the level of loneliness in this population, analyze the multidimensional forms of older adult loneliness, and provide a reference for targeted interventions to reduce loneliness among older adults.