Clinical features of prefrail older individuals and emerging peripheral biomarkers: a systematic review

Frailty is a geriatric syndrome characterized by the clinical presentation of identifiable physical alterations such as loss of muscle mass and strength, energy and exercise tolerance, and decreased physiological reserve. Individuals with one or two of these alterations are defined as prefrail. The clinical features of prefrail older individuals have been investigated to a lesser extent compared to the frail population, even though this intermediate stage may provide insights into the mechanisms involved in the physical decline associated with aging and it is considered to be potentially reversible. We performed searches in the Medline, Embase, Scopus, Cinahl, and Cochrane databases from January 1995 to July 2013 for papers about the identification of prefrail people aged 65 and older published either in English or Spanish, and the reference lists of from the articles retrieved were pearled in order to identify any which may have been missed in the initial search. Two independent reviewers extracted descriptive information on frailty criteria and outcomes from the selected papers: of the 277 articles retrieved from the searches and 25 articles retrieved from pearling, 84 met the study inclusion criteria. The prevalence of prefrailty ranges between 35% and 50% in individuals aged over 60, is more common in women, and the age and the number of comorbidities in these individuals is similar to their frail counterparts. Weakness is the most prevalent symptom in prefrail individuals although there are some sex differences. Some serum biomarkers seem to discriminate prefrail from non-frail individuals but further research would be required to confirm this.