Validation of reaction time as a measure of cognitive function and quality of life in healthy subjects and patients.

OBJECTIVE: Malnutrition is a common problem in hospitalized patients and is related to decreased cognitive function and impaired quality of life (QoL). We investigated the validity of reaction time as a simple bedside tool for measuring cognitive function in healthy subjects and patients, and additionally the relationships with QoL and malnutrition in patients. METHODS: Healthy subjects (N = 130) were assessed for simple and complex reaction time and cognitive function (Addenbrooke cognitive examination, ACE). Patients (N = 70) were assessed for simple and complex reaction time, cognitive function (ACE), and QoL (short-form health survey) (N = 40). RESULTS: Reaction time was related to cognitive function in both healthy subjects and patients. Reaction time was inversely related to the physical component summary of QoL in patients (r = -0.42, P < 0.001). Five of eight QoL scales and the mental component summary of QoL were significantly lower in malnourished patients. Reaction time and ACE were impaired in patients compared to healthy subjects, but not further impaired in malnourished patients. CONCLUSION: Simple reaction time test is related to cognitive function in healthy subjects and patients and to QoL in patients. Complex reaction time test is related to more components of cognitive function. Thus, simple and complex reaction time tests could serve as bedside measurements reflecting, respectively, QoL or cognitive function.

Validation of handgrip strength and endurance as a measure of physical function and quality of life in healthy subjects and patients.

OBJECTIVE: Handgrip strength (HGS) is often used as a bedside measurement of muscle function in the hospital setting. The aim of this study was to investigate the extent to which HGS, endurance, and work (force during endurance x time) are related to physical function as measured by mobility and physical activity (PA) in young, healthy volunteers. Further, the relations between HGS, mobility, PA and quality of life (QoL) in patients were investigated. METHODS: Ninety-two healthy subjects (45% men, mean age 30 y) and 45 patients (56% men, mean age 55 y) were assessed for HGS, handgrip endurance, and handgrip work, mobility (timed up-and-go test), and PA (Baecke questionnaire or Bouchard activity diary). The patients were further assessed for QoL (SF-36). RESULTS: There was a correlation between HGS and mobility in healthy subjects (r=-0.31, P=0.0028) and patients (r=-0.59, P<0.0001). Further, HGS and mobility were related to physical and mental component summary scores of QoL in patients. There was also a relation between HGS and PA in healthy female subjects and male patients. CONCLUSION: Handgrip strength is a valid measurement of mobility and QoL in patients and of PA in healthy female subjects and male patients. Handgrip endurance and work were not found to be valid measurements of mobility and PA in healthy subjects or of QoL in patients.