Predictive validity of a postal questionnaire for screening community-dwelling elderly individuals at risk of functional decline.

Screening elderly individuals who are at risk of functional decline in the community is essential in order to implement effective programmes of assessment and surveillance in a context of secondary prevention. The postal questionnaire technique consists of sending a simple questionnaire to all elderly individuals living in a defined area in order to identify those who are at risk. The objective of this study was to develop a postal questionnaire and to test its capacity to predict functional decline in community-dwelling elderly people. A 21-item postal questionnaire was sent with a birthday card to a representative sample of community-dwelling individuals over the age of 75 years (n = 842). One month after sending the questionnaire, all subjects were contacted by a nurse for an in-home interview (n = 655) that included assessment of functional autonomy. One year later, the subjects (n = 607) were reassessed by the same nurse. Of the eligible subjects, 87.4% returned the postal questionnaire. During the year following the completion of the postal questionnaire, 43 subjects died, 13 were institutionalized and 109 had experienced a significant decrease on the autonomy scale, for a total annual occurrence of functional decline of 27.2%. Age and 14 of the 21 items of the questionnaire were associated with a significant relative risk of functional decline. The relative risk associated with not responding to the questionnaire was 2.1. A stepwise logistic regression analysis showed that six items were independent predictors of functional decline. This 6-item Sherbrooke Postal Questionnaire identifies as positive 56% of the population with 75% sensitivity and 52% specificity. We conclude that a postal questionnaire is a feasible and valid technique for screening elderly individuals at risk for functional decline.