TY - JOUR
T1 - Mediation and moderation
T2 - Testing relationships between symptom status, functional health, and quality of life in HIV patients
AU - Ryu, Ehri
AU - West, Stephen
AU - Sousa, Karen H.
N1 - Funding Information:
This research was supported by National Institute of Nursing Research Grant NRO4817 to Karen Sousa and National Institute on Drug Abuse Grant DA09757 to David MacKinnon.
PY - 2009/3
Y1 - 2009/3
N2 - We extended Wilson and Cleary's (1995) health-related quality of life model to examine the relationships among symptom status (Symptoms), functional health (Disability), and quality of life (QOL). Using a community sample (N = 956) of male HIV positive patients, we tested a mediation model in which the relationship between Symptoms and QOL is partially mediated by Disability. Common and unique ideas from 3 approaches to examining moderation of effects in mediational models (Edwards & Lambert, 2007; MacKinnon, 2008; Preacher, Rucker, & Hayes, 2007) were used to test whether (a) the direct relationship of Symptoms to QOL and (b) the relationship of Disability to QOL are moderated by age. In the mediation model, both the direct and the indirect (mediated) effects were significant. The direct relationship of Symptoms to QOL was significantly moderated by age, but the relationship of Disability to QOL was not. High Symptoms were associated with lower QOL at all ages, but this relationship became stronger at older ages. We compare the 3 approaches and consider their advantages over traditional approaches to combining mediation and moderation.
AB - We extended Wilson and Cleary's (1995) health-related quality of life model to examine the relationships among symptom status (Symptoms), functional health (Disability), and quality of life (QOL). Using a community sample (N = 956) of male HIV positive patients, we tested a mediation model in which the relationship between Symptoms and QOL is partially mediated by Disability. Common and unique ideas from 3 approaches to examining moderation of effects in mediational models (Edwards & Lambert, 2007; MacKinnon, 2008; Preacher, Rucker, & Hayes, 2007) were used to test whether (a) the direct relationship of Symptoms to QOL and (b) the relationship of Disability to QOL are moderated by age. In the mediation model, both the direct and the indirect (mediated) effects were significant. The direct relationship of Symptoms to QOL was significantly moderated by age, but the relationship of Disability to QOL was not. High Symptoms were associated with lower QOL at all ages, but this relationship became stronger at older ages. We compare the 3 approaches and consider their advantages over traditional approaches to combining mediation and moderation.
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U2 - 10.1080/00273170902794222
DO - 10.1080/00273170902794222
M3 - Article
AN - SCOPUS:70449589230
SN - 0027-3171
VL - 44
SP - 213
EP - 232
JO - Multivariate Behavioral Research
JF - Multivariate Behavioral Research
IS - 2
ER -