Validity Of Physical Activity Measured By Proxy-response Questionnaire In Adults With Intellectual Disability

Abstract

Proxy-response questionnaires are widely used to measure physical activity (PA) and sedentary behaviors in adults with intellectual disability (ID). However, there are limited studies documenting the validity of this measurement approach in adults with ID. PURPOSE: This study examined the validity of physical activity and sedentary behavior measured by a proxy-response questionnaire against accelerometry in adults with ID. METHODS: Sixty adults with ID (30 men and 30 women; age 44 ± 14 years) wore an accelerometer (ActiGraph, wGTX-BT) for 7 consecutive days. Caregivers or family members of participants completed the International Physical Activity Questionnaire-Short Form (IPAQ-SF) regarding PA and sedentary behavior for the last 7 days. Spearman’s correlation coefficient estimated the degree of association between IPAQ-SF and accelerometer measurements. The level of agreement between measurements was compared with absolute error and using Bland-Altman plots. RESULTS: There was no significant correlation for moderate PA, vigorous PA and sedentary time between two methods (r = 0.01 - 0.23, p >.05). The Bland-Altman plots indicatd that caregivers and family members reported less sedentary time (-107 min□day-1) and more moderate (+36 min□day-1) and vigorous PA time (+26 min□day-1) compared with the accelerometer measurement. Caregivers and family members underestimated moderate PA days (-1 days□week-1) and overestimated vigorous PA days (+0.75 days□week-1). The absolute error estimates for moderate PA, vigorous PA, and sedentary time were 48.2 ± 75.1%; 26.5 ± 32.6%; and 237.5 ± 127.2%, respectively. The 95% limits of agreement for moderate PA were −124.2 to 197 min□day-1 and for vigorous PA - 46.6 to 81.3 min□day-1. The 95% limits of agreement for sedentary time were - 599 min□day-1 to 378.3 min□day-1. CONCLUSION: There was limited evidence for the validity and accuracy of proxy-measured PA and sedentary time using the IPAQ-SF in adults with ID. This suggests that device-based measurement may be a preferred method in studies of PA in adults with ID.