Prolonged confinement can lead to personal deterioration at various levels. We studied this phenomenon during the nationwide COVID-19 lockdown in a functionally dependent population of the Orcasitas neighborhood of Madrid, Spain, by measuring their ability to perform basic activities of daily living and their mortality rate. A total of 127 patients were included in the Orcasitas cohort. Of this cohort, 78.7% were female, 21.3% were male, and their mean age was 86 years. All participants had a Barthel index of ≤ 60. Changes from pre- to post-confinement and 3 years afterward were analyzed, and the effect of these changes on survival was assessed (2020-2023). The post-confinement functional assessment showed significant improvement in independence over pre-confinement for both the Barthel score (t = -5.823; p < 0.001) and the classification level (z = -2.988; p < 0.003). This improvement progressively disappeared in the following 3 years, and 40.9% of the patients in this cohort died during this period. These outcomes were associated with the Barthel index (z = -3.646; p < 0.001) and the level of dependence (hazard ratio 2.227; CI 1.514-3.276). Higher mortality was observed among men (HR 1.745; CI 1.045-2.915) and those with severe dependence (HR 2.169; CI 1.469-3.201). Setting the cutoff point of the Barthel index at 40 provided the best detection of the risk of death associated with dependence. Home confinement and the risk of death due to the COVID-19 pandemic awakened a form of resilience in the face of adversity among the population of functionally dependent adults. The Barthel index is a good predictor of medium- and long-term mortality and is a useful method for detecting populations at risk in health planning. A cutoff score of 40 is useful for this purpose. To a certain extent, the non-institutionalized dependent population is an invisible population. Future studies should analyze the causes of the high mortality observed.