Frailty, sarcopenia, cachexia and malnutrition as comorbid conditions and their associations with mortality: a prospective study from UK Biobank

Background: Frailty, sarcopenia, cachexia and malnutrition are clinical conditions that share similar diagnostic criteria. This study aimed to investigate the clustering and mortality risk among these clinical conditions in middle- and older-aged adults. Methods: 111 983 participants from UK Biobank were included. Sarcopenia was defined according to the EWGSOP 2019 while frailty using a modified version of the Fried criteria. Cachexia was defined using the Evans et al. classification and malnutrition using the Global Leadership Initiative on Malnutrition. The exposure variable was categorized as: no conditions; frailty only (one condition); frailty with sarcopenia (two conditions); frailty with ≥2 other conditions (three or four conditions). Its association with all-cause mortality was investigated using Cox-proportional hazard analysis. Results: Frailty had the highest prevalence (45%) and was present in 92.1% of people with malnutrition and everyone with sarcopenia or cachexia. Compared with people with no conditions, those with frailty only and frailty with sarcopenia had higher risk of all-cause mortality. Individuals with frailty plus ≥2 other conditions had even higher risk (HR: 4.96 [95% CI: 2.73 to 9.01]). Conclusions: The four clinical conditions investigated overlapped considerably, being frailty the most common. The risk of all-cause mortality increased with the increasing number of conditions in addition to frailty.