Geriatric syndromes can lead to age-related decline in well-being among elderly adults. The signs and symptoms encompassed by geriatric syndromes span multiple physiological systems related to functional dependency. A number of syndromes identified by longitudinal studies are associated with reduced function and quality of life and increased risk of institutionalization and mortality. However, variations in syndrome definitions make systematic discussion of their effects difficult. Routine clinical practice includes assessment of age-related chronic diseases based on accepted diagnostic criteria. In contrast, comprehensive geriatric assessment goes beyond examination for chronic diseases and focuses on functional independence in daily activities and optimal interventions to improve functional status and quality of life. Indeed, comprehensive geriatric assessment emphasizes functional status as a major quality of life factor for older adults. Quality of life improvements for older adults require addressing geriatric syndromes in addition to managing chronic disease. A geriatric syndrome's definition, along with its combination with any chronic disease, affects the syndrome's association with patient-centered outcomes, including quality of life, institutionalization, and mortality. Certain factors are long known to affect patient-centered outcomes. For example, the persistently strong association between self-assessed health status and patient-centered outcomes remains a marvel. Similarly, dependency, defined as deficiencies in activities of daily living (ADLs), also associates strongly with patient-centered outcomes. Systematic reviews have yet to examine other syndromes, such as cognitive impairment, frailty, poor nutrition status, or chronic inflammation for prevalence or association with institutionalization and mortality. This review examines what is known about common geriatric syndromes and their effect on the clinical course of older patients. Our analysis examines the extent to which varying definitions of each syndrome can affect determination of its prevalence and its association with patient-centered outcomes. In general, we anticipate a reciprocal relationship; the more inclusive the definition, the higher the prevalence. More encompassing definitions or those with lower thresholds will inevitably raise prevalence estimates and be less precise in their predictive power than more stringent definitions with higher cut scores. For example, Manton applied ADL- and instrumental activities of daily living (IADL)-related measures for disability to describe a pattern of decline in prevalence over two decades. This review synthesizes the evidence for the following research questions. Key Question 1. What is the definition and prevalence of common syndromes/conditions in older adults? Key Question 2. What is the prevalence of common syndromes/conditions in older adults in sex, age, race, ethnicity, and other subgroups? Key Question 3. What is the association between these common syndromes/conditions and mortality, institutionalization, hospitalization, and activities of daily living? Key Question 4. What statistical and decisionmaking models report mortality based on these common geriatric syndromes/conditions?