Abstract
Unwanted loneliness negatively affects people's health and quality of life, increasing morbidity and the risk of premature death; this situation can generate major social costs. The aim of this study is to estimate the social costs of loneliness in Spain for 2021: both tangible costs -monetary value of health costs and production losses- and intangible costs -Quality Adjusted Life Years (QALYs). To estimate costs not derived from mortality, information from a sample of 400 people with unwanted loneliness was compared with that derived from two samples of the general population obtained from the Spanish National Health Surveys. To estimate the costs associated with premature deaths, the population attributable fraction was calculated using the relative risks estimated in previous survival studies. In the baseline scenario, the tangible costs of unwanted loneliness are estimated to be around 14,129 million euros in 2021, representing 1.2% of Spain's GDP. Approximately 56.8% of the tangible costs correspond to production losses due to reduced working time, and 43.2% are due to healthcare costs related with increased consultation frequency in healthcare services and higher consumption of medicines related to loneliness. In addition, loneliness generates a reduction in quality of life equivalent to 1.04 million QALYs, which corresponds to 2.8% of the total stock of QALYs of the Spanish population over 15 years of age.