Purpose: Mobility limitations and cognitive disorders have often been observed as risks for institutionalization. However, their combined effects on risk of institutionalization among initially community-dwelling older people have been less well reported.

Design: A prospective cohort study with 10-year surveillance on institutionalization.

Subjects: Study population (n = 476) consisted of 75- and 80-year-old people who were community-dwelling, had not been diagnosed with dementia, and participated in tests on walking speed and cognitive capacity at a research centre.

Measures: Cognitive capacity was measured with three validated psychometric tests that were from the Wechsler Adult Intelligence Scale, Wechsler Memory Scale and Schaie-Thurstone Adult Mental Abilities Test. Mobility was measured with walking speed over a 10-m distance. Exclusive distribution based study groups were formed with cut-offs at the lowest third as follows: no limitation, solely mobility limitation, solely cognitive deficits, and combined mobility limitation and cognitive deficits. Cox proportional hazards model was used to determine the relative risks of institutionalization for the study groups.

Results: Eleven percent of the participants were institutionalized during the 10-year surveillance. The risk for institutionalization was 4.9 times greater (95% confidence interval: 2.1-11.2) for those who had co-existing mobility limitations and cognitive deficits than for those with no limitations.

Conclusions: The findings show that the accumulation of limitations in physical and cognitive performance substantially decreases the possibility for a person remaining at home. This might be due to a decreased reserve capacity and ineffective compensatory strategies. Therefore, interventions targeted to improve even one limitation, or prevent accumulation of these risk factors, could significantly reduce the risk of institutionalization.