Data from the Quebec Health Survey (QHS) were used to examine the influence of physical health status on responses to the somatic and affective-cognitive components ofthe QHS psychological distress inventory (PDI) in three age groups (n = 600): 18–39 years, 40–64 years and 65 years and over. A structural equation modelling strategy using LISKEL VIII was employed to test an explanatory model
of the association between physical health and both components of the PDI. The model included sex, perceived life stress, social support, and marital status as covariates. Results showed that the affective-cognitive component of distress was the main explanatory factor in the somatic symptom index. Results also indicated that physical health directly affects responses to the somatic component of the PDI. However, the same effect of physical health on responses to somatic symptoms was found in all three age groups. Findings lead to the conclusion that using a psychological distress measure that includes somatic items, like the PDI, will result in a small overestimation of psychological distress in older adults and younger age groups as well. However, somatic items do not introduce a differential bias in the estimation of respondents' psychological distress status according to age.