@article {1338, title = {Surrogate screening models for the low physical activity criterion of frailty.}, journal = {Aging Clin Exp Res}, volume = {23}, year = {2011}, month = {2011 Jun}, pages = {209-16}, abstract = {

BACKGROUND AND AIMS: Low physical activity, one of five criteria in a validated clinical phenotype of frailty, is assessed by a standardized, semiquantitative questionnaire on up to 20 leisure time activities. Because of the time demanded to collect the interview data, it has been challenging to translate to studies other than the Cardiovascular Health Study (CHS), for which it was developed. Considering subsets of activities, we identified and evaluated streamlined surrogate assessment methods and compared them to one implemented in the Women{\textquoteright}s Health and Aging Study (WHAS).

METHODS: Using data on men and women ages 65 and older from the CHS, we applied logistic regression models to rank activities by "relative influence" in predicting low physical activity.We considered subsets of the most influential activities as inputs to potential surrogate models (logistic regressions). We evaluated predictive accuracy and predictive validity using the area under receiver operating characteristic curves and assessed criterion validity using proportional hazards models relating frailty status (defined using the surrogate) to mortality.

RESULTS: Walking for exercise and moderately strenuous household chores were highly influential for both genders. Women required fewer activities than men for accurate classification. The WHAS model (8 CHS activities) was an effective surrogate, but a surrogate using 6 activities (walking, chores, gardening, general exercise, mowing and golfing) was also highly predictive.

CONCLUSIONS: We recommend a 6 activity questionnaire to assess physical activity for men and women. If efficiency is essential and the study involves only women, fewer activities can be included.

}, keywords = {Activities of Daily Living, Aged, Cohort Studies, Exercise, Female, Follow-Up Studies, Frail Elderly, Geriatric Assessment, Humans, Leisure Activities, Logistic Models, Male, Motor Activity, Prospective Studies, Surveys and Questionnaires, Women{\textquoteright}s Health}, issn = {1594-0667}, author = {Eckel, Sandrah P and Bandeen-Roche, Karen and Chaves, Paulo H M and Fried, Linda P and Louis, Thomas A} } @article {1400, title = {Modification of the association between ambient air pollution and lung function by frailty status among older adults in the Cardiovascular Health Study.}, journal = {Am J Epidemiol}, volume = {176}, year = {2012}, month = {2012 Aug 01}, pages = {214-23}, abstract = {

The susceptibility of older adults to the health effects of air pollution is well-recognized. Advanced age may act as a partial surrogate for conditions associated with aging. The authors investigated whether gerontologic frailty (a clinical health status metric) modified the association between ambient level of ozone or particulate matter with an aerodynamic diameter less than 10 {\textmu}m and lung function in 3,382 older adults using 7 years of follow-up data (1990-1997) from the Cardiovascular Health Study and its Environmental Factors Ancillary Study. Monthly average pollution and annual frailty assessments were related to up to 3 repeated measurements of lung function using cumulative summaries of pollution and frailty histories that accounted for duration as well as concentration. Frailty history was found to modify long-term associations of pollutants with forced vital capacity. For example, the decrease in forced vital capacity associated with a 70-ppb/month greater cumulative sum of monthly average ozone exposure was 12.3 mL (95\% confidence interval: 10.4, 14.2) for a woman who had spent the prior 7 years prefrail or frail as compared with 4.7 mL (95\% confidence interval: 3.8, 5.6) for a similar woman who was robust during all 7 years (interaction P < 0.001).

}, keywords = {Aged, Air Pollution, Cardiovascular Diseases, Female, Forced Expiratory Volume, Frail Elderly, Geriatric Assessment, Humans, Male, Prospective Studies, Respiratory Function Tests, Sex Factors, Smoking, Time Factors, United States, Vital Capacity}, issn = {1476-6256}, doi = {10.1093/aje/kws001}, author = {Eckel, Sandrah P and Louis, Thomas A and Chaves, Paulo H M and Fried, Linda P and Margolis, And Helene G} }